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Sample records for allosteric communication occurs

  1. Mass spectrometry locates local and allosteric conformational changes that occur on cofactor binding

    Science.gov (United States)

    Beveridge, Rebecca; Migas, Lukasz G.; Payne, Karl A. P.; Scrutton, Nigel S.; Leys, David; Barran, Perdita E.

    2016-01-01

    Fdc1 is a decarboxylase enzyme that requires the novel prenylated FMN cofactor for activity. Here, we use it as an exemplar system to show how native top-down and bottom-up mass spectrometry can measure the structural effect of cofactor binding by a protein. For Fdc1Ubix, the cofactor confers structural stability to the enzyme. IM–MS shows the holo protein to exist in four closely related conformational families, the populations of which differ in the apo form; the two smaller families are more populated in the presence of the cofactor and depopulated in its absence. These findings, supported by MD simulations, indicate a more open structure for the apo form. HDX-MS reveals that while the dominant structural changes occur proximal to the cofactor-binding site, rearrangements on cofactor binding are evident throughout the protein, predominantly attributable to allosteric conformational tightening, consistent with IM–MS data. PMID:27418477

  2. Structure-Based Statistical Mechanical Model Accounts for the Causality and Energetics of Allosteric Communication.

    Science.gov (United States)

    Guarnera, Enrico; Berezovsky, Igor N

    2016-03-01

    Allostery is one of the pervasive mechanisms through which proteins in living systems carry out enzymatic activity, cell signaling, and metabolism control. Effective modeling of the protein function regulation requires a synthesis of the thermodynamic and structural views of allostery. We present here a structure-based statistical mechanical model of allostery, allowing one to observe causality of communication between regulatory and functional sites, and to estimate per residue free energy changes. Based on the consideration of ligand free and ligand bound systems in the context of a harmonic model, corresponding sets of characteristic normal modes are obtained and used as inputs for an allosteric potential. This potential quantifies the mean work exerted on a residue due to the local motion of its neighbors. Subsequently, in a statistical mechanical framework the entropic contribution to allosteric free energy of a residue is directly calculated from the comparison of conformational ensembles in the ligand free and ligand bound systems. As a result, this method provides a systematic approach for analyzing the energetics of allosteric communication based on a single structure. The feasibility of the approach was tested on a variety of allosteric proteins, heterogeneous in terms of size, topology and degree of oligomerization. The allosteric free energy calculations show the diversity of ways and complexity of scenarios existing in the phenomenology of allosteric causality and communication. The presented model is a step forward in developing the computational techniques aimed at detecting allosteric sites and obtaining the discriminative power between agonistic and antagonistic effectors, which are among the major goals in allosteric drug design. PMID:26939022

  3. Identifying paths of allosteric communication in the protein BirA through simulations

    Science.gov (United States)

    Custer, Gregory; Beckett, Dorothy; Matysiak, Silvina

    Biotin ligase/repressor (BirA) is a bifunctional enzyme which adenylates biotin and transfers the product, biotinyl-5'-AMP (bio-5'-AMP) to biotin carboxyl carrier protein (BCCP). In the absence of BCCP, bio-5'-AMP promotes the dimerization of BirA. In dimer form, the BirA.bio-5'-AMP complex is able to bind to the biotin operator and prevents further synthesis of biotin. The bio-5'-AMP binds away from the dimer interface, so it is acting as an allosteric activator. We perform all-atom molecular dynamics simulations with BirA to look at fluctuations within the protein at equilibrium. We simulate apoBirA, liganded BirA, as well as two mutants, M211A and V219A. In agreement with experimental observations, several loops of the protein become stabilized for the liganded BirA when compared to the apo protein. In addition, changes in the dimer interface are observed for the M211A and V219A mutations, which are located in the ligand binding region. Using inter-residue correlation coefficients and pair energies a communication network through the protein is constructed. With this network we have identified paths which have the potential to be important in allosteric activation of BirA. These paths and the methods we use to identify them will be presented.

  4. Intramolecular allosteric communication in dopamine D2 receptor revealed by evolutionary amino acid covariation.

    Science.gov (United States)

    Sung, Yun-Min; Wilkins, Angela D; Rodriguez, Gustavo J; Wensel, Theodore G; Lichtarge, Olivier

    2016-03-29

    The structural basis of allosteric signaling in G protein-coupled receptors (GPCRs) is important in guiding design of therapeutics and understanding phenotypic consequences of genetic variation. The Evolutionary Trace (ET) algorithm previously proved effective in redesigning receptors to mimic the ligand specificities of functionally distinct homologs. We now expand ET to consider mutual information, with validation in GPCR structure and dopamine D2 receptor (D2R) function. The new algorithm, called ET-MIp, identifies evolutionarily relevant patterns of amino acid covariations. The improved predictions of structural proximity and D2R mutagenesis demonstrate that ET-MIp predicts functional interactions between residue pairs, particularly potency and efficacy of activation by dopamine. Remarkably, although most of the residue pairs chosen for mutagenesis are neither in the binding pocket nor in contact with each other, many exhibited functional interactions, implying at-a-distance coupling. The functional interaction between the coupled pairs correlated best with the evolutionary coupling potential derived from dopamine receptor sequences rather than with broader sets of GPCR sequences. These data suggest that the allosteric communication responsible for dopamine responses is resolved by ET-MIp and best discerned within a short evolutionary distance. Most double mutants restored dopamine response to wild-type levels, also suggesting that tight regulation of the response to dopamine drove the coevolution and intramolecular communications between coupled residues. Our approach provides a general tool to identify evolutionary covariation patterns in small sets of close sequence homologs and to translate them into functional linkages between residues. PMID:26979958

  5. Molecular Mechanism of Allosteric Communication in Hsp70 Revealed by Molecular Dynamics Simulations

    OpenAIRE

    Chiappori, Federica; Merelli, Ivan; Colombo, Giorgio; Milanesi, Luciano; Morra, Giulia

    2012-01-01

    Author Summary Allostery, or the capability of proteins to respond to ligand binding events with a variation in structure or dynamics at a distant site, is a common feature for biomolecular function and regulation in a large number of proteins. Intra-protein connections and inter-residue coordinations underlie allosteric mechanisms and react to binding primarily through a finely tuned modulation of motions and structures at the microscopic scale. Hence, all-atom molecular dynamics simulations...

  6. Allosteric Mechanisms in Chaperonin Machines.

    Science.gov (United States)

    Gruber, Ranit; Horovitz, Amnon

    2016-06-01

    Chaperonins are nanomachines that facilitate protein folding by undergoing energy (ATP)-dependent movements that are coordinated in time and space owing to complex allosteric regulation. They consist of two back-to-back stacked oligomeric rings with a cavity at each end where protein substrate folding can take place. Here, we focus on the GroEL/GroES chaperonin system from Escherichia coli and, to a lesser extent, on the more poorly characterized eukaryotic chaperonin CCT/TRiC. We describe their various functional (allosteric) states and how they are affected by substrates and allosteric effectors that include ATP, ADP, nonfolded protein substrates, potassium ions, and GroES (in the case of GroEL). We also discuss the pathways of intra- and inter-ring allosteric communication by which they interconvert and the coupling between allosteric transitions and protein folding reactions. PMID:26726755

  7. Allosteric modulation of caspases.

    Science.gov (United States)

    Häcker, Hans-Georg; Sisay, Mihiret Tekeste; Gütschow, Michael

    2011-11-01

    Caspases are proteolytic enzymes mainly involved in the induction and execution phases of apoptosis. This type of programmed cell death is an essential regulatory process required to maintain the integrity and homeostasis of multicellular organisms. Inappropriate apoptosis is attributed a key role in many human diseases, including neurodegenerative disorders, ischemic damage, autoimmune diseases and cancer. Allosteric modulation of the function of a protein occurs when the regulatory trigger, such as the binding of a small effector or inhibitor molecule, takes place some distance from the protein's active site. In recent years, several caspases have been identified that possess allosteric sites and binding of small molecule to these sites resulted in the modulation of enzyme activities. Regulation of caspase activity by small molecule allosteric modulators is believed to be of great therapeutic importance. In this review we give brief highlights on recent developments in identifying and characterizing natural and synthetic allosteric inhibitors as well as activators of caspases and discuss their potential in drug discovery and protein engineering. PMID:21807025

  8. The Allosteric Switching Mechanism in Bacteriophage MS2

    CERN Document Server

    Perkett, Matthew R

    2015-01-01

    In this article we use all-atom simulations to elucidate the mechanisms underlying conformational switching and allostery within the coat protein of the bacteriophage MS2. Assembly of most icosahedral virus capsids requires that the capsid protein adopt different conformations at precise locations within the capsid. It has been shown that a 19 nucleotide stem loop (TR) from the MS2 genome acts as an allosteric effector, guiding conformational switching of the coat protein during capsid assembly. Since the principal conformational changes occur far from the TR binding site, it is important to understand the molecular mechanism underlying this allosteric communication. To this end, we use all-atom simulations with explicit water combined with a path sampling technique to sample the MS2 coat protein conformational transition, in the presence and absence of TR-binding. The calculations find that TR binding strongly alters the transition free energy profile, leading to a switch in the favored conformation. We disc...

  9. Insights into protein -- DNA interactions, stability and allosteric communications: A computational study of MutS-DNA recognition complexes

    Science.gov (United States)

    Negureanu, Lacramioara; Salsbury, Freddie

    2012-02-01

    DNA mismatch repair proteins (MMR) maintain genetic stability by recognizing and repairing mismatched bases and insertion/deletion loops mistakenly incorporated during DNA replication, and initiate cellular response to certain types of DNA damage. The most abundant MMR mismatch-binding factor in eukaryotes, MutS, recognizes and initiates the repair of base-base mismatches and small insertion/deletions. We performed molecular dynamics simulations on mismatched and damaged MutS-DNA complexes. A comprehensive DNA binding site analysis of relevant conformations shows that MutS proteins recognize the mismatched and platinum cross-linked DNA substrates in significantly different modes. Distinctive conformational changes associated with MutS binding to mismatched and damaged DNA have been identified and they provide insight into the involvement of MMR proteins in DNA-repair and DNA-damage pathways. Stability and allosteric interactions at the heterodimer interface associated with the mismatch and damage recognition step allow for prediction of key residues in MMR cancer-causing mutations. A rigorous hydrogen bonding analysis for ADP molecules at the ATPase binding sites is also presented. A large number of known MMR cancer causing mutations among the residues were found.

  10. Differential effects of CSF-1R D802V and KIT D816V homologous mutations on receptor tertiary structure and allosteric communication.

    Directory of Open Access Journals (Sweden)

    Priscila Da Silva Figueiredo Celestino Gomes

    Full Text Available The colony stimulating factor-1 receptor (CSF-1R and the stem cell factor receptor KIT, type III receptor tyrosine kinases (RTKs, are important mediators of signal transduction. The normal functions of these receptors can be compromised by gain-of-function mutations associated with different physiopatological impacts. Whereas KIT D816V/H mutation is a well-characterized oncogenic event and principal cause of systemic mastocytosis, the homologous CSF-1R D802V has not been identified in human cancers. The KIT D816V oncogenic mutation triggers resistance to the RTK inhibitor Imatinib used as first line treatment against chronic myeloid leukemia and gastrointestinal tumors. CSF-1R is also sensitive to Imatinib and this sensitivity is altered by mutation D802V. Previous in silico characterization of the D816V mutation in KIT evidenced that the mutation caused a structure reorganization of the juxtamembrane region (JMR and facilitated its departure from the kinase domain (KD. In this study, we showed that the equivalent CSF-1R D802V mutation does not promote such structural effects on the JMR despite of a reduction on some key H-bonds interactions controlling the JMR binding to the KD. In addition, this mutation disrupts the allosteric communication between two essential regulatory fragments of the receptors, the JMR and the A-loop. Nevertheless, the mutation-induced shift towards an active conformation observed in KIT D816V is not observed in CSF-1R D802V. The distinct impact of equivalent mutation in two homologous RTKs could be associated with the sequence difference between both receptors in the native form, particularly in the JMR region. A local mutation-induced perturbation on the A-loop structure observed in both receptors indicates the stabilization of an inactive non-inhibited form, which Imatinib cannot bind.

  11. An allosteric synthetic DNA.

    OpenAIRE

    Wu, L.; Curran, J F

    1999-01-01

    Allosteric DNA oligonucleotides are potentially useful diagnostic reagents. Here we develop a model system for the study of allosteric interactions in DNAs. A DNA that binds either Cibacron blue or cholic acid was isolated and partially characterized. Isolation was performed using a multi-stage SELEX. First, short oligos that bind either Cibacron blue or cholic acid were enriched from random oligonucleotide pools. Then, members of the two pools were fused to form longer oligos, which were the...

  12. Pathways of allosteric regulation in Hsp70 chaperones

    OpenAIRE

    Kityk, Roman; Vogel, Markus; Schlecht, Rainer; Bukau, Bernd; Mayer, Matthias P

    2015-01-01

    Central to the protein folding activity of Hsp70 chaperones is their ability to interact with protein substrates in an ATP-controlled manner, which relies on allosteric regulation between their nucleotide-binding (NBD) and substrate-binding domains (SBD). Here we dissect this mechanism by analysing mutant variants of the Escherichia coli Hsp70 DnaK blocked at distinct steps of allosteric communication. We show that the SBD inhibits ATPase activity by interacting with the NBD through a highly ...

  13. The allosteric switching mechanism in bacteriophage MS2

    Science.gov (United States)

    Perkett, Matthew R.; Mirijanian, Dina T.; Hagan, Michael F.

    2016-07-01

    We use all-atom simulations to elucidate the mechanisms underlying conformational switching and allostery within the coat protein of the bacteriophage MS2. Assembly of most icosahedral virus capsids requires that the capsid protein adopts different conformations at precise locations within the capsid. It has been shown that a 19 nucleotide stem loop (TR) from the MS2 genome acts as an allosteric effector, guiding conformational switching of the coat protein during capsid assembly. Since the principal conformational changes occur far from the TR binding site, it is important to understand the molecular mechanism underlying this allosteric communication. To this end, we use all-atom simulations with explicit water combined with a path sampling technique to sample the MS2 coat protein conformational transition, in the presence and absence of TR-binding. The calculations find that TR binding strongly alters the transition free energy profile, leading to a switch in the favored conformation. We discuss changes in molecular interactions responsible for this shift. We then identify networks of amino acids with correlated motions to reveal the mechanism by which effects of TR binding span the protein. We find that TR binding strongly affects residues located at the 5-fold and quasi-sixfold interfaces in the assembled capsid, suggesting a mechanism by which the TR binding could direct formation of the native capsid geometry. The analysis predicts amino acids whose substitution by mutagenesis could alter populations of the conformational substates or their transition rates.

  14. Evaluation of multiple schedules with naturally occurring and therapist-arranged discriminative stimuli following functional communication training.

    Science.gov (United States)

    Shamlian, Kenneth D; Fisher, Wayne W; Steege, Mark W; Cavanaugh, Brenna M; Samour, Kristina; Querim, Angie C

    2016-06-01

    Many studies have shown that (a) functional communication training (FCT) is effective for reducing problem behavior, and (b) multiple schedules can facilitate reinforcer schedule thinning during FCT. Most studies tha have used multiple schedules with FCT have included therapist-arranged stimuli (e.g., colored cards) as the discriminative stimuli (S(D) s), but recently, researchers have evaluated similar multiple-schedule training procedures with naturally occurring S(D) s (e.g., overt therapist behavior). The purposes of the current study were to compare the effects of arranged and naturally occurring S(D) s directly during (a) acquisition of discriminated functional communication responses (FCRs) and (b) generalization of discriminated FCRs when we introduced the multiple schedules in novel contexts in which the naturally occurring stimuli were either relatively easy or difficult to discriminate. Results showed that (a) 2 of 3 participants acquired discriminated responding of the FCR more rapidly with arranged than with naturally occurring stimuli, (b) 2 of 3 participants showed resurgence of problem behavior , and (c) 2 of 3 participants showed greater generalization of discriminated responding to novel contexts with arranged stimuli than with naturally occurring stimuli. We discuss these results relative to the conditions under which naturally occurring and arranged S(D) s may promote rapid and generalized treatment gains. PMID:26790565

  15. Modulation of global low-frequency motions underlies allosteric regulation: demonstration in CRP/FNR family transcription factors.

    Directory of Open Access Journals (Sweden)

    Thomas L Rodgers

    2013-09-01

    Full Text Available Allostery is a fundamental process by which ligand binding to a protein alters its activity at a distinct site. There is growing evidence that allosteric cooperativity can be communicated by modulation of protein dynamics without conformational change. The mechanisms, however, for communicating dynamic fluctuations between sites are debated. We provide a foundational theory for how allostery can occur as a function of low-frequency dynamics without a change in structure. We have generated coarse-grained models that describe the protein backbone motions of the CRP/FNR family transcription factors, CAP of Escherichia coli and GlxR of Corynebacterium glutamicum. The latter we demonstrate as a new exemplar for allostery without conformation change. We observe that binding the first molecule of cAMP ligand is correlated with modulation of the global normal modes and negative cooperativity for binding the second cAMP ligand without a change in mean structure. The theory makes key experimental predictions that are tested through an analysis of variant proteins by structural biology and isothermal calorimetry. Quantifying allostery as a free energy landscape revealed a protein "design space" that identified the inter- and intramolecular regulatory parameters that frame CRP/FNR family allostery. Furthermore, through analyzing CAP variants from diverse species, we demonstrate an evolutionary selection pressure to conserve residues crucial for allosteric control. This finding provides a link between the position of CRP/FNR transcription factors within the allosteric free energy landscapes and evolutionary selection pressures. Our study therefore reveals significant features of the mechanistic basis for allostery. Changes in low-frequency dynamics correlate with allosteric effects on ligand binding without the requirement for a defined spatial pathway. In addition to evolving suitable three-dimensional structures, CRP/FNR family transcription factors have

  16. Prediction of allosteric sites and mediating interactions through bond-to-bond propensities

    CERN Document Server

    Amor, Benjamin R C; Yaliraki, Sophia N; Barahona, Mauricio

    2016-01-01

    Allosteric regulation is central to many biochemical processes. Allosteric sites provide a target to fine-tune protein activity, yet we lack computational methods to predict them. Here, we present an efficient graph-theoretical approach for identifying allosteric sites and the mediating interactions that connect them to the active site. Using an atomistic graph with edges weighted by covalent and non-covalent bond energies, we obtain a bond-to-bond propensity that quantifies the effect of instantaneous bond fluctuations propagating through the protein. We use this propensity to detect the sites and communication pathways most strongly linked to the active site, assessing their significance through quantile regression and comparison against a reference set of 100 generic proteins. We exemplify our method in detail with three well-studied allosteric proteins: caspase-1, CheY, and h-Ras, correctly predicting the location of the allosteric site and identifying key allosteric interactions. Consistent prediction of...

  17. Supramolecular Allosteric Cofacial Porphyrin Complexes

    International Nuclear Information System (INIS)

    Nature routinely uses cooperative interactions to regulate cellular activity. For years, chemists have designed synthetic systems that aim toward harnessing the reactivity common to natural biological systems. By learning how to control these interactions in situ, one begins to allow for the preparation of man-made biomimetic systems that can efficiently mimic the interactions found in Nature. To this end, we have designed a synthetic protocol for the preparation of flexible metal-directed supramolecular cofacial porphyrin complexes which are readily obtained in greater than 90% yield through the use of new hemilabile porphyrin ligands with bifunctional ether-phosphine or thioether-phosphine substituents at the 5 and 15 positions on the porphyrin ring. The resulting architectures contain two hemilabile ligand-metal domains (RhI or CuI sites) and two cofacially aligned porphyrins (ZnII sites), offering orthogonal functionalities and allowing these multimetallic complexes to exist in two states, 'condensed' or 'open'. Combining the ether-phosphine ligand with the appropriate RhI or CuI transition-metal precursors results in 'open' macrocyclic products. In contrast, reacting the thioether-phosphine ligand with RhI or CuI precursors yields condensed structures that can be converted into their 'open' macrocyclic forms via introduction of additional ancillary ligands. The change in cavity size that occurs allows these structures to function as allosteric catalysts for the acyl transfer reaction between X-pyridylcarbinol (where X = 2, 3, or 4) and 1-acetylimidazole. For 3- and 4-pyridylcarbinol, the 'open' macrocycle accelerates the acyl transfer reaction more than the condensed analogue and significantly more than the porphyrin monomer. In contrast, an allosteric effect was not observed for 2-pyridylcarbinol, which is expected to be a weaker binder and is unfavorably constrained inside the macrocyclic cavity.

  18. Supramolecular Allosteric Cofacial Porphyrin Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Oliveri, Christopher G.; Gianneschi, Nathan C.; Nguyen, Son Binh T.; Mirkin, Chad A.; Stern, Charlotte L.; Wawrzak, Zdzislaw; Pink, Maren (NWU); (Indiana)

    2008-04-12

    Nature routinely uses cooperative interactions to regulate cellular activity. For years, chemists have designed synthetic systems that aim toward harnessing the reactivity common to natural biological systems. By learning how to control these interactions in situ, one begins to allow for the preparation of man-made biomimetic systems that can efficiently mimic the interactions found in Nature. To this end, we have designed a synthetic protocol for the preparation of flexible metal-directed supramolecular cofacial porphyrin complexes which are readily obtained in greater than 90% yield through the use of new hemilabile porphyrin ligands with bifunctional ether-phosphine or thioether-phosphine substituents at the 5 and 15 positions on the porphyrin ring. The resulting architectures contain two hemilabile ligand-metal domains (Rh{sup I} or Cu{sup I} sites) and two cofacially aligned porphyrins (Zn{sup II} sites), offering orthogonal functionalities and allowing these multimetallic complexes to exist in two states, 'condensed' or 'open'. Combining the ether-phosphine ligand with the appropriate Rh{sup I} or Cu{sup I} transition-metal precursors results in 'open' macrocyclic products. In contrast, reacting the thioether-phosphine ligand with RhI or CuI precursors yields condensed structures that can be converted into their 'open' macrocyclic forms via introduction of additional ancillary ligands. The change in cavity size that occurs allows these structures to function as allosteric catalysts for the acyl transfer reaction between X-pyridylcarbinol (where X = 2, 3, or 4) and 1-acetylimidazole. For 3- and 4-pyridylcarbinol, the 'open' macrocycle accelerates the acyl transfer reaction more than the condensed analogue and significantly more than the porphyrin monomer. In contrast, an allosteric effect was not observed for 2-pyridylcarbinol, which is expected to be a weaker binder and is unfavorably constrained inside the

  19. Pathways of allosteric regulation in Hsp70 chaperones.

    Science.gov (United States)

    Kityk, Roman; Vogel, Markus; Schlecht, Rainer; Bukau, Bernd; Mayer, Matthias P

    2015-01-01

    Central to the protein folding activity of Hsp70 chaperones is their ability to interact with protein substrates in an ATP-controlled manner, which relies on allosteric regulation between their nucleotide-binding (NBD) and substrate-binding domains (SBD). Here we dissect this mechanism by analysing mutant variants of the Escherichia coli Hsp70 DnaK blocked at distinct steps of allosteric communication. We show that the SBD inhibits ATPase activity by interacting with the NBD through a highly conserved hydrogen bond network, and define the signal transduction pathway that allows bound substrates to trigger ATP hydrolysis. We identify variants deficient in only one direction of allosteric control and demonstrate that ATP-induced substrate release is more important for chaperone activity than substrate-stimulated ATP hydrolysis. These findings provide evidence of an unexpected dichotomic allostery mechanism in Hsp70 chaperones and provide the basis for a comprehensive mechanical model of allostery in Hsp70s. PMID:26383706

  20. Are AMPA Receptor Positive Allosteric Modulators Potential Pharmacotherapeutics for Addiction?

    OpenAIRE

    Lucas R. Watterson; M. Foster Olive

    2013-01-01

    Positive allosteric modulators (PAMs) of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors are a diverse class of compounds that increase fast excitatory transmission in the brain. AMPA PAMs have been shown to facilitate long-term potentiation, strengthen communication between various cortical and subcortical regions, and some of these compounds increase the production and release of brain-derived neurotrophic factor (BDNF) in an activity-dependent manner. Through these m...

  1. Allosteric Modulation of Muscarinic Receptors

    Czech Academy of Sciences Publication Activity Database

    Jakubík, Jan; El-Fakahany, E. E.

    New York: Springer, 2016 - (Mysliveček, J.; Jakubík, J.), s. 95-130. (Neuromethods. 107). ISBN 978-1-4939-2857-6 R&D Projects: GA ČR(CZ) GBP304/12/G069 Institutional support: RVO:67985823 Keywords : muscarinic receptors * allosteric modulation * radioligand binding functional response Subject RIV: ED - Physiology

  2. Allosteric Modulation of Muscarinic Acetylcholine Receptors

    Directory of Open Access Journals (Sweden)

    Esam E. El-Fakahany

    2010-08-01

    Full Text Available An allosteric modulator is a ligand that binds to an allosteric site on the receptor and changes receptor conformation to produce increase (positive cooperativity or decrease (negative cooperativity in the binding or action of an orthosteric agonist (e.g., acetylcholine. Since the identification of gallamine as the first allosteric modulator of muscarinic receptors in 1976, this unique mode of receptor modulation has been intensively studied by many groups. This review summarizes over 30 years of research on the molecular mechanisms of allosteric interactions of drugs with the receptor and for new allosteric modulators of muscarinic receptors with potential therapeutic use. Identification of positive modulators of acetylcholine binding and function that enhance neurotransmission and the discovery of highly selective allosteric modulators are mile-stones on the way to novel therapeutic agents for the treatment of schizophrenia, Alzheimer’s disease and other disorders involving impaired cognitive function.

  3. Allosteric transition: a comparison of two models

    DEFF Research Database (Denmark)

    Bindslev, Niels

    2013-01-01

    Introduction Two recent models are in use for analysis of allosteric drug action at receptor sites remote from orthosteric binding sites. One is an allosteric two-state mechanical model derived in 2000 by David Hall. The other is an extended operational model developed in 2007 by Arthur Christopo......Introduction Two recent models are in use for analysis of allosteric drug action at receptor sites remote from orthosteric binding sites. One is an allosteric two-state mechanical model derived in 2000 by David Hall. The other is an extended operational model developed in 2007 by Arthur...

  4. NMR Characterization of Information Flow and Allosteric Communities in the MAP Kinase p38γ

    Science.gov (United States)

    Aoto, Phillip C.; Martin, Bryan T.; Wright, Peter E.

    2016-01-01

    The intramolecular network structure of a protein provides valuable insights into allosteric sites and communication pathways. However, a straightforward method to comprehensively map and characterize these pathways is not currently available. Here we present an approach to characterize intramolecular network structure using NMR chemical shift perturbations. We apply the method to the mitogen activated protein kinase (MAPK) p38γ. p38γ contains allosteric sites that are conserved among eukaryotic kinases as well as unique to the MAPK family. How these regulatory sites communicate with catalytic residues is not well understood. Using our method, we observe and characterize for the first time information flux between regulatory sites through a conserved kinase infrastructure. This network is accessed, reinforced, and broken in various states of p38γ, reflecting the functional state of the protein. We demonstrate that the approach detects critical junctions in the network corresponding to biologically significant allosteric sites and pathways.

  5. NMR Characterization of Information Flow and Allosteric Communities in the MAP Kinase p38γ.

    Science.gov (United States)

    Aoto, Phillip C; Martin, Bryan T; Wright, Peter E

    2016-01-01

    The intramolecular network structure of a protein provides valuable insights into allosteric sites and communication pathways. However, a straightforward method to comprehensively map and characterize these pathways is not currently available. Here we present an approach to characterize intramolecular network structure using NMR chemical shift perturbations. We apply the method to the mitogen activated protein kinase (MAPK) p38γ. p38γ contains allosteric sites that are conserved among eukaryotic kinases as well as unique to the MAPK family. How these regulatory sites communicate with catalytic residues is not well understood. Using our method, we observe and characterize for the first time information flux between regulatory sites through a conserved kinase infrastructure. This network is accessed, reinforced, and broken in various states of p38γ, reflecting the functional state of the protein. We demonstrate that the approach detects critical junctions in the network corresponding to biologically significant allosteric sites and pathways. PMID:27353957

  6. Allosteric function and dysfunction of the prion protein.

    Science.gov (United States)

    Linden, Rafael; Cordeiro, Yraima; Lima, Luis Mauricio T R

    2012-04-01

    Transmissible spongiform encephalopathies (TSEs) are neurodegenerative diseases associated with progressive oligo- and multimerization of the prion protein (PrP(C)), its conformational conversion, aggregation and precipitation. We recently proposed that PrP(C) serves as a cell surface scaffold protein for a variety of signaling modules, the effects of which translate into wide-range functional consequences. Here we review evidence for allosteric functions of PrP(C), which constitute a common property of scaffold proteins. The available data suggest that allosteric effects among PrP(C) and its partners are involved in the assembly of multi-component signaling modules at the cell surface, impose upon both physiological and pathological conformational responses of PrP(C), and that allosteric dysfunction of PrP(C) has the potential to entail progressive signal corruption. These properties may be germane both to physiological roles of PrP(C), as well as to the pathogenesis of the TSEs and other degenerative/non-communicable diseases. PMID:21984610

  7. Identification of the Allosteric Regulatory Site of Insulysin

    Energy Technology Data Exchange (ETDEWEB)

    Noinaj, Nicholas; Bhasin, Sonia K.; Song, Eun Suk; Scoggin, Kirsten E.; Juliano, Maria A.; Juliano, Luiz; Hersh, Louis B.; Rodgers, David W. (U. Sao Paulo); (Kentucky)

    2012-05-25

    Insulin degrading enzyme (IDE) is responsible for the metabolism of insulin and plays a role in clearance of the A{beta} peptide associated with Alzheimer's disease. Unlike most proteolytic enzymes, IDE, which consists of four structurally related domains and exists primarily as a dimer, exhibits allosteric kinetics, being activated by both small substrate peptides and polyphosphates such as ATP. The crystal structure of a catalytically compromised mutant of IDE has electron density for peptide ligands bound at the active site in domain 1 and a distal site in domain 2. Mutating residues in the distal site eliminates allosteric kinetics and activation by a small peptide, as well as greatly reducing activation by ATP, demonstrating that this site plays a key role in allostery. Comparison of the peptide bound IDE structure (using a low activity E111F IDE mutant) with unliganded wild type IDE shows a change in the interface between two halves of the clamshell-like molecule, which may enhance enzyme activity by altering the equilibrium between closed and open conformations. In addition, changes in the dimer interface suggest a basis for communication between subunits. Our findings indicate that a region remote from the active site mediates allosteric activation of insulysin by peptides. Activation may involve a small conformational change that weakens the interface between two halves of the enzyme.

  8. Modeling amperometric biosensors based on allosteric enzymes

    Directory of Open Access Journals (Sweden)

    Liutauras Ričkus

    2013-09-01

    Full Text Available Computational modeling of a biosensor with allosteric enzyme layer was investigated in this study. The operation of the biosensor is modeled using non-stationary reaction-diffusion equations. The model involves three regions: the allosteric enzyme layer where the allosteric enzyme reactions as well as then mass transport by diffusion take place, the diffusion region where the mass transport by diffusion and non-enzymatic reactions take place and the convective region in which the analyte concentration is maintained constant. The biosensor response on dependency substrate concentration, cooperativity coefficient and the diffusion layer thickness on the same parameters have been studied.

  9. Zinc as Allosteric Ion Channel Modulator: Ionotropic Receptors as Metalloproteins.

    Science.gov (United States)

    Peralta, Francisco Andrés; Huidobro-Toro, Juan Pablo

    2016-01-01

    Zinc is an essential metal to life. This transition metal is a structural component of many proteins and is actively involved in the catalytic activity of cell enzymes. In either case, these zinc-containing proteins are metalloproteins. However, the amino acid residues that serve as ligands for metal coordination are not necessarily the same in structural proteins compared to enzymes. While crystals of structural proteins that bind zinc reveal a higher preference for cysteine sulfhydryls rather than histidine imidazole rings, catalytic enzymes reveal the opposite, i.e., a greater preference for the histidines over cysteines for catalysis, plus the influence of carboxylic acids. Based on this paradigm, we reviewed the putative ligands of zinc in ionotropic receptors, where zinc has been described as an allosteric modulator of channel receptors. Although these receptors do not strictly qualify as metalloproteins since they do not normally bind zinc in structural domains, they do transitorily bind zinc at allosteric sites, modifying transiently the receptor channel's ion permeability. The present contribution summarizes current information showing that zinc allosteric modulation of receptor channels occurs by the preferential metal coordination to imidazole rings as well as to the sulfhydryl groups of cysteine in addition to the carboxyl group of acid residues, as with enzymes and catalysis. It is remarkable that most channels, either voltage-sensitive or transmitter-gated receptor channels, are susceptible to zinc modulation either as positive or negative regulators. PMID:27384555

  10. Zinc as Allosteric Ion Channel Modulator: Ionotropic Receptors as Metalloproteins

    Science.gov (United States)

    Peralta, Francisco Andrés; Huidobro-Toro, Juan Pablo

    2016-01-01

    Zinc is an essential metal to life. This transition metal is a structural component of many proteins and is actively involved in the catalytic activity of cell enzymes. In either case, these zinc-containing proteins are metalloproteins. However, the amino acid residues that serve as ligands for metal coordination are not necessarily the same in structural proteins compared to enzymes. While crystals of structural proteins that bind zinc reveal a higher preference for cysteine sulfhydryls rather than histidine imidazole rings, catalytic enzymes reveal the opposite, i.e., a greater preference for the histidines over cysteines for catalysis, plus the influence of carboxylic acids. Based on this paradigm, we reviewed the putative ligands of zinc in ionotropic receptors, where zinc has been described as an allosteric modulator of channel receptors. Although these receptors do not strictly qualify as metalloproteins since they do not normally bind zinc in structural domains, they do transitorily bind zinc at allosteric sites, modifying transiently the receptor channel’s ion permeability. The present contribution summarizes current information showing that zinc allosteric modulation of receptor channels occurs by the preferential metal coordination to imidazole rings as well as to the sulfhydryl groups of cysteine in addition to the carboxyl group of acid residues, as with enzymes and catalysis. It is remarkable that most channels, either voltage-sensitive or transmitter-gated receptor channels, are susceptible to zinc modulation either as positive or negative regulators. PMID:27384555

  11. Detection of allosteric signal transmission by information-theoretic analysis of protein dynamics

    Science.gov (United States)

    Pandini, Alessandro; Fornili, Arianna; Fraternali, Franca; Kleinjung, Jens

    2012-01-01

    Allostery offers a highly specific way to modulate protein function. Therefore, understanding this mechanism is of increasing interest for protein science and drug discovery. However, allosteric signal transmission is difficult to detect experimentally and to model because it is often mediated by local structural changes propagating along multiple pathways. To address this, we developed a method to identify communication pathways by an information-theoretical analysis of molecular dynamics simulations. Signal propagation was described as information exchange through a network of correlated local motions, modeled as transitions between canonical states of protein fragments. The method was used to describe allostery in two-component regulatory systems. In particular, the transmission from the allosteric site to the signaling surface of the receiver domain NtrC was shown to be mediated by a layer of hub residues. The location of hubs preferentially connected to the allosteric site was found in close agreement with key residues experimentally identified as involved in the signal transmission. The comparison with the networks of the homologues CheY and FixJ highlighted similarities in their dynamics. In particular, we showed that a preorganized network of fragment connections between the allosteric and functional sites exists already in the inactive state of all three proteins.—Pandini, A., Fornili, A., Fraternali, F., Kleinjung, J. Detection of allosteric signal transmission by information-theoretic analysis of protein dynamics. PMID:22071506

  12. Markov propagation of allosteric effects in biomolecular systems: application to GroEL–GroES

    OpenAIRE

    Chennubhotla, Chakra; Bahar, Ivet

    2006-01-01

    We introduce a novel approach for elucidating the potential pathways of allosteric communication in biomolecular systems. The methodology, based on Markov propagation of ‘information' across the structure, permits us to partition the network of interactions into soft clusters distinguished by their coherent stochastics. Probabilistic participation of residues in these clusters defines the communication patterns inherent to the network architecture. Application to bacterial chaperonin complex ...

  13. The Role of Protein-Ligand Contacts in Allosteric Regulation of the Escherichia coli Catabolite Activator Protein*

    Science.gov (United States)

    Townsend, Philip D.; Rodgers, Thomas L.; Glover, Laura C.; Korhonen, Heidi J.; Richards, Shane A.; Colwell, Lucy J.; Pohl, Ehmke; Wilson, Mark R.; Hodgson, David R. W.; McLeish, Tom C. B.; Cann, Martin J.

    2015-01-01

    Allostery is a fundamental process by which ligand binding to a protein alters its activity at a distant site. Both experimental and theoretical evidence demonstrate that allostery can be communicated through altered slow relaxation protein dynamics without conformational change. The catabolite activator protein (CAP) of Escherichia coli is an exemplar for the analysis of such entropically driven allostery. Negative allostery in CAP occurs between identical cAMP binding sites. Changes to the cAMP-binding pocket can therefore impact the allosteric properties of CAP. Here we demonstrate, through a combination of coarse-grained modeling, isothermal calorimetry, and structural analysis, that decreasing the affinity of CAP for cAMP enhances negative cooperativity through an entropic penalty for ligand binding. The use of variant cAMP ligands indicates the data are not explained by structural heterogeneity between protein mutants. We observe computationally that altered interaction strength between CAP and cAMP variously modifies the change in allosteric cooperativity due to second site CAP mutations. As the degree of correlated motion between the cAMP-contacting site and a second site on CAP increases, there is a tendency for computed double mutations at these sites to drive CAP toward noncooperativity. Naturally occurring pairs of covarying residues in CAP do not display this tendency, suggesting a selection pressure to fine tune allostery on changes to the CAP ligand-binding pocket without a drive to a noncooperative state. In general, we hypothesize an evolutionary selection pressure to retain slow relaxation dynamics-induced allostery in proteins in which evolution of the ligand-binding site is occurring. PMID:26187469

  14. Rational Engineering of Enzyme Allosteric Regulation through Sequence Evolution Analysis

    OpenAIRE

    Jae-Seong Yang; Sang Woo Seo; Sungho Jang; Gyoo Yeol Jung; Sanguk Kim

    2012-01-01

    Control of enzyme allosteric regulation is required to drive metabolic flux toward desired levels. Although the three-dimensional (3D) structures of many enzyme-ligand complexes are available, it is still difficult to rationally engineer an allosterically regulatable enzyme without decreasing its catalytic activity. Here, we describe an effective strategy to deregulate the allosteric inhibition of enzymes based on the molecular evolution and physicochemical characteristics of allosteric ligan...

  15. Prediction of allosteric sites and mediating interactions through bond-to-bond propensities

    Science.gov (United States)

    Amor, B. R. C.; Schaub, M. T.; Yaliraki, S. N.; Barahona, M.

    2016-01-01

    Allostery is a fundamental mechanism of biological regulation, in which binding of a molecule at a distant location affects the active site of a protein. Allosteric sites provide targets to fine-tune protein activity, yet we lack computational methodologies to predict them. Here we present an efficient graph-theoretical framework to reveal allosteric interactions (atoms and communication pathways strongly coupled to the active site) without a priori information of their location. Using an atomistic graph with energy-weighted covalent and weak bonds, we define a bond-to-bond propensity quantifying the non-local effect of instantaneous bond fluctuations propagating through the protein. Significant interactions are then identified using quantile regression. We exemplify our method with three biologically important proteins: caspase-1, CheY, and h-Ras, correctly predicting key allosteric interactions, whose significance is additionally confirmed against a reference set of 100 proteins. The almost-linear scaling of our method renders it suitable for high-throughput searches for candidate allosteric sites. PMID:27561351

  16. Allosteric modulation of caspase 3 through mutagenesis

    Directory of Open Access Journals (Sweden)

    Jad Walters

    2012-06-01

    Full Text Available A mutation in the allosteric site of the caspase 3 dimer interface of Val266 to histidine abolishes activity of the enzyme, and models predict that the mutation mimics the action of small molecule allosteric inhibitors by preventing formation of the active site. Mutations were coupled to His266 at two sites in the interface, E124A and Y197C. We present results from X-ray crystallography, enzymatic activity and molecular dynamics simulations for seven proteins, consisting of single, double and triple mutants. The results demonstrate that considering allosteric inhibition of caspase 3 as a shift between discrete ‘off-state’ or ‘on-state’ conformations is insufficient. Although His266 is accommodated in the interface, the structural defects are propagated to the active site through a helix on the protein surface. A more comprehensive view of allosteric regulation of caspase 3 requires the representation of an ensemble of inactive states and shows that subtle structural changes lead to the population of the inactive ensemble.

  17. Allosteric Modulation of Muscarinic Acetylcholine Receptors

    Czech Academy of Sciences Publication Activity Database

    Jakubík, Jan; El-Fakahany, E. E.

    2010-01-01

    Roč. 3, č. 9 (2010), s. 2838-2860. ISSN 1424-8247 R&D Projects: GA ČR GA305/09/0681 Institutional research plan: CEZ:AV0Z50110509 Keywords : muscarinic acetylcholine receptors * allosteric modulation * Alzheimer ´s disease Subject RIV: CE - Biochemistry

  18. Heat Capacity Changes and Disorder-to-Order Transitions in Allosteric Activation.

    Science.gov (United States)

    Cressman, William J; Beckett, Dorothy

    2016-01-19

    Allosteric coupling in proteins is ubiquitous but incompletely understood, particularly in systems characterized by coupling over large distances. Binding of the allosteric effector, bio-5'-AMP, to the Escherichia coli biotin protein ligase, BirA, enhances the protein's dimerization free energy by -4 kcal/mol. Previous studies revealed that disorder-to-order transitions at the effector binding and dimerization sites, which are separated by 33 Å, are integral to functional coupling. Perturbations to the transition at the ligand binding site alter both ligand binding and coupled dimerization. Alanine substitutions in four loops on the dimerization surface yield a range of energetic effects on dimerization. A glycine to alanine substitution at position 142 in one of these loops results in a complete loss of allosteric coupling, disruption of the disorder-to-order transitions at both functional sites, and a decreased affinity for the effector. In this work, allosteric communication between the effector binding and dimerization surfaces in BirA was further investigated by performing isothermal titration calorimetry measurements on nine proteins with alanine substitutions in three dimerization surface loops. In contrast to BirAG142A, at 20 °C all variants bind to bio-5'-AMP with free energies indistinguishable from that measured for wild-type BirA. However, the majority of the variants exhibit altered heat capacity changes for effector binding. Moreover, the ΔCp values correlate with the dimerization free energies of the effector-bound proteins. These thermodynamic results, combined with structural information, indicate that allosteric activation of the BirA monomer involves formation of a network of intramolecular interactions on the dimerization surface in response to bio-5'-AMP binding at the distant effector binding site. PMID:26678378

  19. Coupled Dynamics and Entropic Contribution to the Allosteric Mechanism of Pin1.

    Science.gov (United States)

    Barman, Arghya; Hamelberg, Donald

    2016-08-25

    Allosteric communication in proteins regulates a plethora of downstream processes in subcellular signaling pathways. Describing the effects of cooperative ligand binding on the atomic level is a key to understanding many regulatory processes involving biomolecules. Here, we use microsecond-long molecular dynamics simulations to investigate the allosteric mechanism of Pin1, a potential therapeutic target and a phosphorylated-Ser/Thr dependent peptidyl-prolyl cis-trans isomerase that regulates several subcellular processes and has been implicated in many diseases, including cancer and Alzheimer's. Experimental studies suggest that the catalytic domain and the noncatalytic WW domain are allosterically coupled; however, an atomic level description of the dynamics associated with the interdomain communication is lacking. We show that binding of the substrate to the WW domain is directly coupled to the dynamics of the catalytic domain, causing rearrangement of the residue-residue contact dynamics from the WW domain to the catalytic domain. The binding affinity of the substrate in the catalytic domain is also enhanced upon binding of the substrate to the WW domain. Modulation of the dynamics of the catalytic domain upon binding of the substrate to the WW domain leads to prepayment of the entropic cost of binding the substrate to the catalytic domain. This study shows that Ile 28 at the interfacial region between the catalytic and WW domains is certainly one of the residues responsible for bridging the communication between the two domains. The results complement previous experiments and provide valuable atomistic insights into the role of dynamics and possible entropic contribution to the allosteric mechanism of proteins. PMID:27077947

  20. Exploiting protein flexibility to predict the location of allosteric sites

    Directory of Open Access Journals (Sweden)

    Panjkovich Alejandro

    2012-10-01

    Full Text Available Abstract Background Allostery is one of the most powerful and common ways of regulation of protein activity. However, for most allosteric proteins identified to date the mechanistic details of allosteric modulation are not yet well understood. Uncovering common mechanistic patterns underlying allostery would allow not only a better academic understanding of the phenomena, but it would also streamline the design of novel therapeutic solutions. This relatively unexplored therapeutic potential and the putative advantages of allosteric drugs over classical active-site inhibitors fuel the attention allosteric-drug research is receiving at present. A first step to harness the regulatory potential and versatility of allosteric sites, in the context of drug-discovery and design, would be to detect or predict their presence and location. In this article, we describe a simple computational approach, based on the effect allosteric ligands exert on protein flexibility upon binding, to predict the existence and position of allosteric sites on a given protein structure. Results By querying the literature and a recently available database of allosteric sites, we gathered 213 allosteric proteins with structural information that we further filtered into a non-redundant set of 91 proteins. We performed normal-mode analysis and observed significant changes in protein flexibility upon allosteric-ligand binding in 70% of the cases. These results agree with the current view that allosteric mechanisms are in many cases governed by changes in protein dynamics caused by ligand binding. Furthermore, we implemented an approach that achieves 65% positive predictive value in identifying allosteric sites within the set of predicted cavities of a protein (stricter parameters set, 0.22 sensitivity, by combining the current analysis on dynamics with previous results on structural conservation of allosteric sites. We also analyzed four biological examples in detail, revealing

  1. Molecular Basis of Enhanced Activity in Factor VIIa-Trypsin Variants Conveys Insights into Tissue Factor-mediated Allosteric Regulation of Factor VIIa Activity

    DEFF Research Database (Denmark)

    Sorensen, Anders B.; Madsen, Jesper Jonasson; Svensson, L. Anders; Pedersen, Anette A.; Østergaard, Henrik; Overgaard, Michael T.; Olsen, Ole H.; Gandhi, Prafull S

    2016-01-01

    The complex of coagulation factor VIIa (FVIIa), a trypsin-like serine protease, and membrane-bound tissue factor (TF) initiates blood coagulation upon vascular injury. Binding of TF to FVIIa promotes allosteric conformational changes in the FVIIa protease domain and improves its catalytic...... properties. Extensive studies have revealed two putative pathways for this allosteric communication. Here we provide further details of this allosteric communication by investigating FVIIa loop swap variants containing the 170 loop of trypsin that display TF-independent enhanced activity. Using x......-ray crystallography, we show that the introduced 170 loop from trypsin directly interacts with the FVIIa active site, stabilizing segment 215-217 and activation loop 3, leading to enhanced activity. Molecular dynamics simulations and novel fluorescence quenching studies support that segment 215-217 conformation is...

  2. Rational engineering of enzyme allosteric regulation through sequence evolution analysis.

    Directory of Open Access Journals (Sweden)

    Jae-Seong Yang

    Full Text Available Control of enzyme allosteric regulation is required to drive metabolic flux toward desired levels. Although the three-dimensional (3D structures of many enzyme-ligand complexes are available, it is still difficult to rationally engineer an allosterically regulatable enzyme without decreasing its catalytic activity. Here, we describe an effective strategy to deregulate the allosteric inhibition of enzymes based on the molecular evolution and physicochemical characteristics of allosteric ligand-binding sites. We found that allosteric sites are evolutionarily variable and comprised of more hydrophobic residues than catalytic sites. We applied our findings to design mutations in selected target residues that deregulate the allosteric activity of fructose-1,6-bisphosphatase (FBPase. Specifically, charged amino acids at less conserved positions were substituted with hydrophobic or neutral amino acids with similar sizes. The engineered proteins successfully diminished the allosteric inhibition of E. coli FBPase without affecting its catalytic efficiency. We expect that our method will aid the rational design of enzyme allosteric regulation strategies and facilitate the control of metabolic flux.

  3. Structural basis for drug-induced allosteric changes to human β-cardiac myosin motor activity

    Science.gov (United States)

    Winkelmann, Donald A.; Forgacs, Eva; Miller, Matthew T.; Stock, Ann M.

    2015-08-01

    Omecamtiv Mecarbil (OM) is a small molecule allosteric effector of cardiac myosin that is in clinical trials for treatment of systolic heart failure. A detailed kinetic analysis of cardiac myosin has shown that the drug accelerates phosphate release by shifting the equilibrium of the hydrolysis step towards products, leading to a faster transition from weak to strong actin-bound states. The structure of the human β-cardiac motor domain (cMD) with OM bound reveals a single OM-binding site nestled in a narrow cleft separating two domains of the human cMD where it interacts with the key residues that couple lever arm movement to the nucleotide state. In addition, OM induces allosteric changes in three strands of the β-sheet that provides the communication link between the actin-binding interface and the nucleotide pocket. The OM-binding interactions and allosteric changes form the structural basis for the kinetic and mechanical tuning of cardiac myosin.

  4. Allosteric small-molecule kinase inhibitors

    DEFF Research Database (Denmark)

    Wu, Peng; Clausen, Mads Hartvig; Nielsen, Thomas E.

    2015-01-01

    Small-molecule kinase inhibitors are invaluable targeted therapeutics for the treatment of various human diseases, especially cancers. While the majority of approved and developed preclinical small-molecule inhibitors are characterized as type I or type II inhibitors that target the ATP......-binding pocket of kinases, the remarkable sequential and structural similarity among ATP pockets renders the selective inhibition of kinases a daunting challenge. Therefore, targeting allosteric pockets of kinases outside the highly conversed ATP pocket has been proposed as a promising alternative to overcome...

  5. Brief communication "A pre seismic radio anomaly revealed in the area where the Abruzzo earthquake (M=6.3 occurred on 6 April 2009"

    Directory of Open Access Journals (Sweden)

    T. Ligonzo

    2010-02-01

    Full Text Available We report the information that in the days of the radio anomaly presented in the paper Biagi et al. (2009 an interruption of the broadcasting from the transmitter (RMC, France happened. It remains unclear if the action resulted in a complete power off of the system, or in a reduction in the radiated power, and if this has affected France only, or every direction. Should a complete power off have occurred, the proposed pre-seismic defocusing is inexistent. Our doubts on this action are reported.

  6. Are AMPA receptor positive allosteric modulators potential pharmacotherapeutics for addiction?

    Science.gov (United States)

    Watterson, Lucas R; Olive, M Foster

    2013-01-01

    Positive allosteric modulators (PAMs) of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors are a diverse class of compounds that increase fast excitatory transmission in the brain. AMPA PAMs have been shown to facilitate long-term potentiation, strengthen communication between various cortical and subcortical regions, and some of these compounds increase the production and release of brain-derived neurotrophic factor (BDNF) in an activity-dependent manner. Through these mechanisms, AMPA PAMs have shown promise as broad spectrum pharmacotherapeutics in preclinical and clinical studies for various neurodegenerative and psychiatric disorders. In recent years, a small collection of preclinical animal studies has also shown that AMPA PAMs may have potential as pharmacotherapeutic adjuncts to extinction-based or cue-exposure therapies for the treatment of drug addiction. The present paper will review this preclinical literature, discuss novel data collected in our laboratory, and recommend future research directions for the possible development of AMPA PAMs as anti-addiction medications. PMID:24380895

  7. Are AMPA Receptor Positive Allosteric Modulators Potential Pharmacotherapeutics for Addiction?

    Directory of Open Access Journals (Sweden)

    Lucas R. Watterson

    2013-12-01

    Full Text Available Positive allosteric modulators (PAMs of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA receptors are a diverse class of compounds that increase fast excitatory transmission in the brain. AMPA PAMs have been shown to facilitate long-term potentiation, strengthen communication between various cortical and subcortical regions, and some of these compounds increase the production and release of brain-derived neurotrophic factor (BDNF in an activity-dependent manner. Through these mechanisms, AMPA PAMs have shown promise as broad spectrum pharmacotherapeutics in preclinical and clinical studies for various neurodegenerative and psychiatric disorders. In recent years, a small collection of preclinical animal studies has also shown that AMPA PAMs may have potential as pharmacotherapeutic adjuncts to extinction-based or cue-exposure therapies for the treatment of drug addiction. The present paper will review this preclinical literature, discuss novel data collected in our laboratory, and recommend future research directions for the possible development of AMPA PAMs as anti-addiction medications.

  8. Communications

    Science.gov (United States)

    Bailenson, Jeremy; Buzzanell, Patrice; Deetz, Stanley; Tewksbury, David; Thompson, Robert J.; Turow, Joseph; Bichelmeyer, Barbara; Bishop, M. J.; Gayeski, Diane

    2013-01-01

    Scholars representing the field of communications were asked to identify what they considered to be the most exciting and imaginative work currently being done in their field, as well as how that work might change our understanding. The scholars included Jeremy Bailenson, Patrice Buzzanell, Stanley Deetz, David Tewksbury, Robert J. Thompson, and…

  9. Allosteric Regulation by a Critical Membrane

    CERN Document Server

    Kimchi, Ofer; Machta, Benjamin B

    2016-01-01

    Many of the processes that underly neural computation are carried out by ion channels embedded in the plasma membrane, a two-dimensional liquid that surrounds all cells. Recent experiments have demonstrated that this membrane is poised close to a liquid-liquid critical point in the Ising universality class. Here we use both exact and stochastic techniques on the lattice Ising model to explore the ramifications of proximity to criticality for proteins that are allosterically coupled to Ising composition modes. Owing to diverging generalized susceptibilities, such a protein's activity becomes strongly influenced by perturbations that influence the two relevant parameters of the critical point, especially the critical temperature. In addition, the protein's kinetics acquire a range of time scales from its surrounding membrane, naturally leading to non-Markovian dynamics.

  10. Allosteric modulation of G-protein coupled receptors

    DEFF Research Database (Denmark)

    Jensen, Anders A.; Spalding, Tracy A

    2004-01-01

    The superfamily of G-protein coupled receptors (GPCRs) has more than 1000 members and is the largest family of proteins in the body. GPCRs mediate signalling of stimuli as diverse as light, ions, small molecules, peptides and proteins and are the targets for many pharmaceuticals. Most GPCR ligands...... are believed to activate (agonists) or inhibit (competitive antagonists) receptor signalling by binding the receptor at the same site as the endogenous agonist, the orthosteric site. In contrast, allosteric ligands modulate receptor function by binding to different regions in the receptor, allosteric...... outlines the current status and perspectives of allosteric modulation of GPCR function with emphasis on the pharmacology of endogenous and synthesised modulators, their receptor interactions and the therapeutic prospects of allosteric ligands compared to orthosteric ligands....

  11. A unified framework and an alternative mechanism for allosteric regulation

    CERN Document Server

    Xing, J

    2007-01-01

    Allosteric regulation is an important property for many proteins. Several models have been proposed to explain the allosteric effect, such as the concerted MWC (Monod, Wyman, Changeux) model, the sequential KNF (Koshland, Nemethy, Filmer) model, and recent population shift models. Here we discuss a unified theoretical framework to describe allosteric effects. The existing models appear as special cases of the framework. The theoretical work also reveals an alternative mechanism currently overlooked. Theoretically it is possible that the reactivity of a protein is limited by some internal conformational change step (due to slow effective diffusion along rugged potential surfaces). Effector binding may modify the ruggedness and thus the protein dynamics and reactivity. Compared to conventional models, the new mechanism has less requirements on the mechanical properties of an allosteric protein to propagate mechanical signals over long distances. Thus some signal transduction proteins may adopt the new mechanism...

  12. Computational study on the inhibitor binding mode and allosteric regulation mechanism in hepatitis C virus NS3/4A protein.

    Directory of Open Access Journals (Sweden)

    Weiwei Xue

    Full Text Available HCV NS3/4A protein is an attractive therapeutic target responsible for harboring serine protease and RNA helicase activities during the viral replication. Small molecules binding at the interface between the protease and helicase domains can stabilize the closed conformation of the protein and thus block the catalytic function of HCV NS3/4A protein via an allosteric regulation mechanism. But the detailed mechanism remains elusive. Here, we aimed to provide some insight into the inhibitor binding mode and allosteric regulation mechanism of HCV NS3/4A protein by using computational methods. Four simulation systems were investigated. They include: apo state of HCV NS3/4A protein, HCV NS3/4A protein in complex with an allosteric inhibitor and the truncated form of the above two systems. The molecular dynamics simulation results indicate HCV NS3/4A protein in complex with the allosteric inhibitor 4VA adopts a closed conformation (inactive state, while the truncated apo protein adopts an open conformation (active state. Further residue interaction network analysis suggests the communication of the domain-domain interface play an important role in the transition from closed to open conformation of HCV NS3/4A protein. However, the inhibitor stabilizes the closed conformation through interaction with several key residues from both the protease and helicase domains, including His57, Asp79, Asp81, Asp168, Met485, Cys525 and Asp527, which blocks the information communication between the functional domains interface. Finally, a dynamic model about the allosteric regulation and conformational changes of HCV NS3/4A protein was proposed and could provide fundamental insights into the allosteric mechanism of HCV NS3/4A protein function regulation and design of new potent inhibitors.

  13. Designing allosteric control into enzymes by chemical rescue of structure

    OpenAIRE

    Deckert, Katelyn; Budiardjo, S. Jimmy; Brunner, Luke C.; Lovell, Scott; Karanicolas, John

    2012-01-01

    Ligand-dependent activity has been engineered into enzymes for purposes ranging from controlling cell morphology to reprogramming cellular signaling pathways. Where these successes have typically fused a naturally allosteric domain to the enzyme of interest, here we instead demonstrate an approach for designing a de novo allosteric effector site directly into the catalytic domain of an enzyme. This approach is distinct from traditional chemical rescue of enzymes in that it relies on disruptio...

  14. Positive allosteric action of eburnamonine on cardiac muscarinic acetylcholine receptors.

    Science.gov (United States)

    Proska, J; Tucek, S

    1996-06-01

    It was discovered recently that alcuronium and strychnine (which is a precursor of alcuronium) allosterically increase the affinity of cardiac muscarinic receptors for the antagonist, N-methylscopolamine. We have now investigated the effects of l-eburnamonine and vincamine, which are both closely related to strychnine. In experiments on rat heart atria, l-eburnamonine was found to increase the binding of [3H]N-methylscopolamine with Ehlert's cooperativity coefficient alpha = 0.35, which indicates that the strength of its allosteric action is close to that of alcuronium and strychnine (alpha = 0.31 and 0.44, respectively). However, the affinity of l-eburnamonine for the cardiac muscarinic receptors is lower than the affinities of alcuronium and strychnine (KAR = 22.6 microM, 0.15 microM, and 3.4 microM, respectively). In spite of its extremely close similarity to l-eburnamonine, vincamine has a negative allosteric effect on the binding of [3H]N-methylscopolamine (alpha = 4.1; KAR = 22.8 microM). It is likely that a systematic investigation of the allosteric effects of the analogues of strychnine will not only yield new allosteric effectors on muscarinic receptors, but also clarify the structural features responsible for the direction (positive or negative) of their allosteric effect. PMID:8813554

  15. COMMUNICATIONS

    CERN Multimedia

    L. Taylor and D. Barney

    2010-01-01

    CMS Centres, Outreach and the 7 TeV Media Event The new CMS Communications group is now established and is addressing three areas that are critical to CMS as it enters the physics operations phase: - Communications Infrastructure, including almost 50 CMS Centres Worldwide, videoconferencing systems, and CERN meeting rooms - Information systems, including the internal and external Web sites as well as the document preparation and management systems - Outreach and Education activities, including working with print, radio and TV media, visits to CMS, and exhibitions. The group has been active in many areas, with the highest priority being accorded to needs of CMS operations and preparations for the major media event planned for 7 TeV collisions. Unfortunately the CMS Centre@CERN suffered a major setback when, on 21st December, a cooling water pipe froze and burst on the floor above the CMS Centre main room. Water poured through the ceiling, flooding the floor and soaking some of the consoles, before e...

  16. COMMUNICATIONS

    CERN Multimedia

    A. Petrilli

    2013-01-01

    The organisation of the Open Days at the end of September was the single biggest effort of the CMS Communications Group this year. We would like to thank all volunteers for their hard work to show our Point 5 facilities and explain science and technology to the general public. During two days more than 5,000 people visited the CMS detector underground and profited from the surface activities, which included an exhibition on CMS, a workshop on superconductivity, and an activity for our younger visitors involving wooden Kapla blocks. The Communications Group took advantage of the preparations to produce new CMS posters that can be reused at other venues. Event display images have been produced not just for this occasion but also for other exhibits, education purposes, publications etc. During the Open Days, Gilles Jobin, 2012 winner of CERN Collide@CERN prize, performed his Quantum show in Point 5, with the light installation of German artist Julius von Bismarck. Image 3: CERN Open Days at CMS wel...

  17. Study on the Model for Regulation of the Allosteric Enzyme Activity

    Institute of Scientific and Technical Information of China (English)

    LI,Qian-Zhong(李前忠); LUO,Liao-Fu(罗辽复); ZHANG,Li-Rong(张利绒)

    2002-01-01

    The effects of activator molecule and repressive molecule on binding process between allosteric enzyme and substrate are disused by considering the heterotropic effect of the regulating molecule that binds to allosteric enzyme. A model of allosteric enzyme with heterotropic effect is presented. The cooperativity and anticooperativity in the regulation process are studied.

  18. Preferential binding of allosteric modulators to active and inactive conformational states of metabotropic glutamate receptors

    Directory of Open Access Journals (Sweden)

    Klein-Seetharaman Judith

    2008-02-01

    Full Text Available Abstract Metabotropic glutamate receptors (mGluRs are G protein coupled receptors that play important roles in synaptic plasticity and other neuro-physiological and pathological processes. Allosteric mGluR ligands are particularly promising drug targets because of their modulatory effects – enhancing or suppressing the response of mGluRs to glutamate. The mechanism by which this modulation occurs is not known. Here, we propose the hypothesis that positive and negative modulators will differentially stabilize the active and inactive conformations of the receptors, respectively. To test this hypothesis, we have generated computational models of the transmembrane regions of different mGluR subtypes in two different conformations. The inactive conformation was modeled using the crystal structure of the inactive, dark state of rhodopsin as template and the active conformation was created based on a recent model of the light-activated state of rhodopsin. Ligands for which the nature of their allosteric effects on mGluRs is experimentally known were docked to the modeled mGluR structures using ArgusLab and Autodock softwares. We find that the allosteric ligand binding pockets of mGluRs are overlapping with the retinal binding pocket of rhodopsin, and that ligands have strong preferences for the active and inactive states depending on their modulatory nature. In 8 out of 14 cases (57%, the negative modulators bound the inactive conformations with significant preference using both docking programs, and 6 out of 9 cases (67%, the positive modulators bound the active conformations. Considering results by the individual programs only, even higher correlations were observed: 12/14 (86% and 8/9 (89% for ArgusLab and 10/14 (71% and 7/9 (78% for AutoDock. These findings strongly support the hypothesis that mGluR allosteric modulation occurs via stabilization of different conformations analogous to those identified in rhodopsin where they are induced by

  19. Novel Inhibitors Complexed with Glutamate Dehydrogenase: ALLOSTERIC REGULATION BY CONTROL OF PROTEIN DYNAMICS

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ming; Smith, Christopher J.; Walker, Matthew T.; Smith, Thomas J.; (Danforth)

    2009-12-01

    Mammalian glutamate dehydrogenase (GDH) is a homohexameric enzyme that catalyzes the reversible oxidative deamination of L-glutamate to 2-oxoglutarate using NAD(P){sup +} as coenzyme. Unlike its counterparts from other animal kingdoms, mammalian GDH is regulated by a host of ligands. The recently discovered hyperinsulinism/hyperammonemia disorder showed that the loss of allosteric inhibition of GDH by GTP causes excessive secretion of insulin. Subsequent studies demonstrated that wild-type and hyperinsulinemia/hyperammonemia forms of GDH are inhibited by the green tea polyphenols, epigallocatechin gallate and epicatechin gallate. This was followed by high throughput studies that identified more stable inhibitors, including hexachlorophene, GW5074, and bithionol. Shown here are the structures of GDH complexed with these three compounds. Hexachlorophene forms a ring around the internal cavity in GDH through aromatic stacking interactions between the drug and GDH as well as between the drug molecules themselves. In contrast, GW5074 and bithionol both bind as pairs of stacked compounds at hexameric 2-fold axes between the dimers of subunits. The internal core of GDH contracts when the catalytic cleft closes during enzymatic turnover. None of the drugs cause conformational changes in the contact residues, but all bind to key interfaces involved in this contraction process. Therefore, it seems likely that the drugs inhibit enzymatic turnover by inhibiting this transition. Indeed, this expansion/contraction process may play a major role in the inter-subunit communication and allosteric regulation observed in GDH.

  20. Allosteric modulation of the effect of escitalopram, paroxetine and fluoxetine: in-vitro and in-vivo studies

    DEFF Research Database (Denmark)

    Mansari, Mostafa El; Wiborg, Ove; Mnie-Filali, Ouissame;

    2006-01-01

    escitalopram. This effect was suggested to occur via an allosteric modulation at the level of the 5-HT transporter. Using in-vitro binding assays at membranes from COS-1 cells expressing the human 5-HT transporter (hSERT) and in-vivo electrophysiological and microdialysis techniques in rats, the present study...... was directed at determining whether R-citalopram modifies the action of selective serotonin reuptake inhibitors (SSRIs) known to act on allosteric sites namely escitalopram, and to a lesser extent paroxetine, compared to fluoxetine, which has no affinity for these sites. In-vitro binding studies...... showed that R-citalopram attenuated the association rates of escitalopram and paroxetine to the 5-HT transporter, but had no effect on the association rates of fluoxetine, venlafaxine or sertraline. In the rat dorsal raphe nucleus, R-citalopram (250 microg/kg i.v.) blocked the suppressant effect on...

  1. Metal ion coupled protein folding and allosteric motions

    Science.gov (United States)

    Wang, Wei

    2014-03-01

    Many proteins need the help of cofactors for their successful folding and functioning. Metal ions, i.e., Zn2+, Ca2+, and Mg2+ etc., are typical biological cofactors. Binding of metal ions can reshape the energy landscapes of proteins, thereby modifying the folding and allosteric motions. For example, such binding may make the intrinsically disordered proteins have funneled energy landscapes, consequently, ensures their spontaneous folding. In addition, the binding may activate certain biological processes by inducing related conformational changes of regulation proteins. However, how the local interactions involving the metal ion binding can induce the global conformational motions of proteins remains elusive. Investigating such question requires multiple models with different details, including quantum mechanics, atomistic models, and coarse grained models. In our recent work, we have been developing such multiscale methods which can reasonably model the metal ion binding induced charge transfer, protonation/deprotonation, and large conformational motions of proteins. With such multiscale model, we elucidated the zinc-binding induced folding mechanism of classical zinc finger and the calcium-binding induced dynamic symmetry breaking in the allosteric motions of calmodulin. In addition, we studied the coupling of folding, calcium binding and allosteric motions of calmodulin domains. In this talk, I will introduce the above progresses on the metal ion coupled protein folding and allosteric motions. We thank the finacial support from NSFC and the 973 project.

  2. Allosteric role of the large-scale domain opening in biological catch-binding

    Science.gov (United States)

    Pereverzev, Yuriy V.; Prezhdo, Oleg V.; Sokurenko, Evgeni V.

    2009-05-01

    The proposed model demonstrates the allosteric role of the two-domain region of the receptor protein in the increased lifetimes of biological receptor/ligand bonds subjected to an external force. The interaction between the domains is represented by a bounded potential, containing two minima corresponding to the attached and separated conformations of the two protein domains. The dissociative potential with a single minimum describing receptor/ligand binding fluctuates between deep and shallow states, depending on whether the domains are attached or separated. A number of valuable analytic expressions are derived and are used to interpret experimental data for two catch bonds. The P-selectin/P-selectin-glycoprotein-ligand-1 (PSGL-1) bond is controlled by the interface between the epidermal growth factor (EGF) and lectin domains of P-selectin, and the type 1 fimbrial adhesive protein (FimH)/mannose bond is governed by the interface between the lectin and pilin domains of FimH. Catch-binding occurs in these systems when the external force stretches the receptor proteins and increases the interdomain distance. The allosteric effect is supported by independent measurements, in which the domains are kept separated by attachment of another ligand. The proposed model accurately describes the experimentally observed anomalous behavior of the lifetimes of the P-selectin/PSGL-1 and FimH/mannose complexes as a function of applied force and provides valuable insights into the mechanism of catch-binding.

  3. Enzyme activity and allosteric characteristics of gamma-irradiated solid aspartate transcarbamylase

    International Nuclear Information System (INIS)

    Aspartate transcarbamylase purified from E. coli was lyophilized, irradiated in vacuo with γ radiation from a cesium-137 source, redissolved in buffer under a nitrogen atmosphere, and assayed for enzyme activity. Lyophilized and redissolved enzyme had normal catalytic and allosteric kinetic characteristics. The average D37 observed with saturating substrate, 25 mM aspartate, was 4.1 Mrad. With less than saturating substrate, 5 mM aspartate, the activity increases from zero to 1.6 Mrad and then decreases with a D37 of 7.2 Mrad. Inclusion of 1 mM CTP, an allosteric inhibitor, in the 5 mM aspartate assays results in a more pronounced maximum in the activity curve occurring at slightly higher dose, 2.2 Mrad. Inhibitability by CTP has a D37 of 2.3 Mrad with doses below the activity maximum. Enzyme lyophilized in the presence of 1 mM CTP has a D37 of 2.9 Mrad. ATCase activity changes caused by irradiation of lyophylized bacteria were qualitatively like the changes observed in the detailed studies with the purified enzyme. Apparent radiation sensitivities of ATCase in lyophilized bacteria were observed to vary with the technique used to disrupt the resuspended bacteria

  4. Extracellular loop 2 of the free Fatty Acid receptor 2 mediates allosterism of a phenylacetamide ago-allosteric modulator

    DEFF Research Database (Denmark)

    Smith, Nicola J; Ward, Richard J; Stoddart, Leigh A; Hudson, Brian D; Kostenis, Evi; Ulven, Trond; Morris, Joanne C; Tränkle, Christian; Tikhonova, Irina G; Adams, David R; Milligan, Graeme

    2011-01-01

    Allosteric agonists are powerful tools for exploring the pharmacology of closely related G protein-coupled receptors that have nonselective endogenous ligands, such as the short chain fatty acids at free fatty acid receptors 2 and 3 (FFA2/GPR43 and FFA3/GPR41, respectively). We explored the molec...

  5. Allosteric Pathways in the PPARγ-RXRα nuclear receptor complex

    Science.gov (United States)

    Ricci, Clarisse G.; Silveira, Rodrigo L.; Rivalta, Ivan; Batista, Victor S.; Skaf, Munir S.

    2016-01-01

    Understanding the nature of allostery in DNA-nuclear receptor (NR) complexes is of fundamental importance for drug development since NRs regulate the transcription of a myriad of genes in humans and other metazoans. Here, we investigate allostery in the peroxisome proliferator-activated/retinoid X receptor heterodimer. This important NR complex is a target for antidiabetic drugs since it binds to DNA and functions as a transcription factor essential for insulin sensitization and lipid metabolism. We find evidence of interdependent motions of Ω-loops and PPARγ-DNA binding domain with contacts susceptible to conformational changes and mutations, critical for regulating transcriptional functions in response to sequence-dependent DNA dynamics. Statistical network analysis of the correlated motions, observed in molecular dynamics simulations, shows preferential allosteric pathways with convergence centers comprised of polar amino acid residues. These findings are particularly relevant for the design of allosteric modulators of ligand-dependent transcription factors.

  6. Allosterism and Structure in Thermally Activated Transient Receptor Potential Channels.

    Science.gov (United States)

    Diaz-Franulic, Ignacio; Poblete, Horacio; Miño-Galaz, Germán; González, Carlos; Latorre, Ramón

    2016-07-01

    The molecular sensors that mediate temperature changes in living organisms are a large family of proteins known as thermosensitive transient receptor potential (TRP) ion channels. These membrane proteins are polymodal receptors that can be activated by cold or hot temperatures, depending on the channel subtype, voltage, and ligands. The stimuli sensors are allosterically coupled to a pore domain, increasing the probability of finding the channel in its ion conductive conformation. In this review we first discuss the allosteric coupling between the temperature and voltage sensor modules and the pore domain, and then discuss the thermodynamic foundations of thermo-TRP channel activation. We provide a structural overview of the molecular determinants of temperature sensing. We also posit an anisotropic thermal diffusion model that may explain the large temperature sensitivity of TRP channels. Additionally, we examine the effect of several ligands on TRP channel function and the evidence regarding their mechanisms of action. PMID:27297398

  7. Allosteric process of human glucokinase conducive to fight against diabetes

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ More than 200 million people worldwide have diabetes. In China alone, about 60 million people are suffering from the disease.Fortunately, scientists are pushing back its boundaries. For instance, a recent study by CAS researchers may shed new light on the treatment of the disease by making cutting-edge progress on studies of the allosteric process of human glucokinase, which has been published by the latest issue of the Proceedings of National Academy of Sciences.

  8. Allosteric activation of coagulation factor VIIa visualized by hydrogen exchange

    DEFF Research Database (Denmark)

    Rand, Kasper Dyrberg; Jørgensen, Thomas; Olsen, Ole H; Persson, Egon; Jensen, Ole; Stennicke, Henning R; Andersen, Mette

    2006-01-01

    Coagulation factor VIIa (FVIIa) is a serine protease that, after binding to tissue factor (TF), plays a pivotal role in the initiation of blood coagulation. We used hydrogen exchange monitored by mass spectrometry to visualize the details of FVIIa activation by comparing the exchange kinetics of ...... provide novel insights into the cofactor-induced activation of this important protease and reveal the potential for allosteric regulation in the trypsin family of proteases....

  9. Divergent allosteric patterns verify the regulatory paradigm for aspartate transcarbamylase.

    Science.gov (United States)

    Wales, M E; Madison, L L; Glaser, S S; Wild, J R

    1999-12-17

    The native Escherichia coli aspartate transcarbamoylase (ATCase, E.C. 2.1.3.2) provides a classic allosteric model for the feedback inhibition of a biosynthetic pathway by its end products. Both E. coli and Erwinia herbicola possess ATCase holoenzymes which are dodecameric (2(c3):3(r2)) with 311 amino acid residues per catalytic monomer and 153 and 154 amino acid residues per regulatory (r) monomer, respectively. While the quaternary structures of the two enzymes are identical, the primary amino acid sequences have diverged by 14 % in the catalytic polypeptide and 20 % in the regulatory polypeptide. The amino acids proposed to be directly involved in the active site and nucleotide binding site are strictly conserved between the two enzymes; nonetheless, the two enzymes differ in their catalytic and regulatory characteristics. The E. coli enzyme has sigmoidal substrate binding with activation by ATP, and inhibition by CTP, while the E. herbicola enzyme has apparent first order kinetics at low substrate concentrations in the absence of allosteric ligands, no ATP activation and only slight CTP inhibition. In an apparently important and highly conserved characteristic, CTP and UTP impose strong synergistic inhibition on both enzymes. The co-operative binding of aspartate in the E. coli enzyme is correlated with a T-to-R conformational transition which appears to be greatly reduced in the E. herbicola enzyme, although the addition of inhibitory heterotropic ligands (CTP or CTP+UTP) re-establishes co-operative saturation kinetics. Hybrid holoenzymes assembled in vivo with catalytic subunits from E. herbicola and regulatory subunits from E. coli mimick the allosteric response of the native E. coli holoenzyme and exhibit ATP activation. The reverse hybrid, regulatory subunits from E. herbicola and catalytic subunits from E. coli, exhibited no response to ATP. The conserved structure and diverged functional characteristics of the E. herbicola enzyme provides an opportunity

  10. The structural basis of ATP as an allosteric modulator.

    OpenAIRE

    Shaoyong Lu; Wenkang Huang; Qi Wang; Qiancheng Shen; Shuai Li; Ruth Nussinov; Jian Zhang

    2014-01-01

    Adenosine-5'-triphosphate (ATP) is generally regarded as a substrate for energy currency and protein modification. Recent findings uncovered the allosteric function of ATP in cellular signal transduction but little is understood about this critical behavior of ATP. Through extensive analysis of ATP in solution and proteins, we found that the free ATP can exist in the compact and extended conformations in solution, and the two different conformational characteristics may be responsible for ATP...

  11. The Structural Basis of ATP as an Allosteric Modulator

    OpenAIRE

    Lu, Shaoyong; Huang, Wenkang; Wang, Qi; Shen, Qiancheng; Li, Shuai; Nussinov, Ruth; Zhang, Jian

    2014-01-01

    Adenosine-5’-triphosphate (ATP) is generally regarded as a substrate for energy currency and protein modification. Recent findings uncovered the allosteric function of ATP in cellular signal transduction but little is understood about this critical behavior of ATP. Through extensive analysis of ATP in solution and proteins, we found that the free ATP can exist in the compact and extended conformations in solution, and the two different conformational characteristics may be responsible for ATP...

  12. Computational approaches to detect allosteric pathways in transmembrane molecular machines.

    Science.gov (United States)

    Stolzenberg, Sebastian; Michino, Mayako; LeVine, Michael V; Weinstein, Harel; Shi, Lei

    2016-07-01

    Many of the functions of transmembrane proteins involved in signal processing and transduction across the cell membrane are determined by allosteric couplings that propagate the functional effects well beyond the original site of activation. Data gathered from breakthroughs in biochemistry, crystallography, and single molecule fluorescence have established a rich basis of information for the study of molecular mechanisms in the allosteric couplings of such transmembrane proteins. The mechanistic details of these couplings, many of which have therapeutic implications, however, have only become accessible in synergy with molecular modeling and simulations. Here, we review some recent computational approaches that analyze allosteric coupling networks (ACNs) in transmembrane proteins, and in particular the recently developed Protein Interaction Analyzer (PIA) designed to study ACNs in the structural ensembles sampled by molecular dynamics simulations. The power of these computational approaches in interrogating the functional mechanisms of transmembrane proteins is illustrated with selected examples of recent experimental and computational studies pursued synergistically in the investigation of secondary active transporters and GPCRs. This article is part of a Special Issue entitled: Membrane Proteins edited by J.C. Gumbart and Sergei Noskov. PMID:26806157

  13. Allosteric indicator displacement enzyme assay for a cyanogenic glycoside.

    Science.gov (United States)

    Jose, D Amilan; Elstner, Martin; Schiller, Alexander

    2013-10-18

    Indicator displacement assays (IDAs) represent an elegant approach in supramolecular analytical chemistry. Herein, we report a chemical biosensor for the selective detection of the cyanogenic glycoside amygdalin in aqueous solution. The hybrid sensor consists of the enzyme β-glucosidase and a boronic acid appended viologen together with a fluorescent reporter dye. β-Glucosidase degrades the cyanogenic glycoside amygdalin into hydrogen cyanide, glucose, and benzaldehyde. Only the released cyanide binds at the allosteric site of the receptor (boronic acid) thereby inducing changes in the affinity of a formerly bound fluorescent indicator dye at the other side of the receptor. Thus, the sensing probe performs as allosteric indicator displacement assay (AIDA) for cyanide in water. Interference studies with inorganic anions and glucose revealed that cyanide is solely responsible for the change in the fluorescent signal. DFT calculations on a model compound revealed a 1:1 binding ratio of the boronic acid and cyanide ion. The fluorescent enzyme assay for β-glucosidase uses amygdalin as natural substrate and allows measuring Michaelis-Menten kinetics in microtiter plates. The allosteric indicator displacement assay (AIDA) probe can also be used to detect cyanide traces in commercial amygdalin samples. PMID:24123550

  14. pH dependence of the kinetic properties of allosteric phosphofructokinase from Escherichia coli.

    Science.gov (United States)

    Deville-Bonne, D; Bourgain, F; Garel, J R

    1991-06-11

    The pH dependence of the activity of the allosteric phosphofructokinase from Escherichia coli has been studied in the pH range from 6 to 9, in the absence or presence of allosteric effectors. The sigmoidal cooperative saturation of phosphofructokinase by fructose 6-phosphate has been analyzed according to the Hill equation, and the following results have been obtained: (i) the apparent affinity for Fru-6P, as measured by the half-saturating concentration, [Fru-6P]0.5, does not change with pH; (ii) the cooperativity, as measured empirically by the Hill coefficient, nH, increases markedly with pH and reaches a value of 5.5-6 at pH 9; (iii) the catalytic rate constant, kcat, is controlled by the ionization of a critical group which has a pK of 7 in the absence of effector and must be deprotonated for phosphofructokinase to be active. The observation that pH affects both the cooperativity and the maximum velocity suggests that the catalytic efficiency of a given active site could be modified by the binding of fructose 6-phosphate to other remote sites. Finding values of the cooperativity coefficient larger than the number of substrate binding sites indicates that slow conformational changes may occur in phosphofructokinase. The cooperative saturation of phosphofructokinase by fructose 6-phosphate appears more complex than described by the classical concerted model at steady state and could involve two slowly interconverting states which differ in both their turnover rate constants and their affinities for fructose 6-phosphate. The presence of GDP shifts the pK of the critical group which controls kcat from 7 to 6.6.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1828369

  15. Interdomain Interactions Support Interdomain Communication in Human Pin1

    OpenAIRE

    Wilson, Kimberly A.; Bouchard, Jill J.; Peng, Jeffrey W.

    2013-01-01

    Pin1 is an essential mitotic regulator consisting of a peptidyl–prolyl isomerase (PPIase) domain flexibly tethered to a smaller Trp–Trp (WW) binding domain. Communication between these domains is important for Pin1 in vivo activity; however, the atomic basis for this communication has remained elusive. Our previous nuclear magnetic resonance (NMR) studies of Pin1 functional dynamics suggested that weak interdomain contacts within Pin1 enable allosteric communication between the domain interfa...

  16. The therapeutic potential of allosteric ligands for free fatty acid sensitive GPCRs

    DEFF Research Database (Denmark)

    Hudson, Brian D; Ulven, Trond; Milligan, Graeme

    2013-01-01

    identifying allosteric leads and their often flat or confusing SAR. The present review will consider the advantages and challenges associated with allosteric GPCR ligands, and examine how the particular properties of these ligands may be exploited to uncover the therapeutic potential for free fatty acid...

  17. Activation and Allosteric Modulation of Human μ Opioid Receptor in Molecular Dynamics.

    Science.gov (United States)

    Bartuzi, Damian; Kaczor, Agnieszka A; Matosiuk, Dariusz

    2015-11-23

    Allosteric protein modulation has gained increasing attention in drug design. Its application as a mechanism of action could bring forth safer and more effective medicines. Targeting opioid receptors with allosteric modulators can result in better treatment of pain, depression, and respiratory and immune disorders. In this work we use recent reports on negative modulators of μ opioid receptor as a starting point for identification of allosteric sites and mechanisms of opioid receptor modulation using homology modeling and docking and molecular dynamics studies. An allosteric binding site description is presented. Results suggest a shared binding region for lipophilic allosteric ligands, reveal possible differences in the modulation mechanism between cannabinoids and salvinorin A, and show ambiguous properties of the latter. Also, they emphasize the importance of native-like environment in molecular dynamics simulations and uncover relationships between modulator and orthosteric ligand binding and receptor behavior. Relationships between ligands, transmission switch, and hydrophobic lock are analyzed. PMID:26517559

  18. Allosteric activation mechanism of the cys-loop receptors

    Institute of Scientific and Technical Information of China (English)

    Yong-chang CHANG; Wen WU; Jian-liang ZHANG; Yao HUANG

    2009-01-01

    Binding of a neurotransmitter to its ionotropic receptor opens a distantly located ion channel, a process termed allosteric activation. Here we review recent advances in the molecular mechanism by which the cys-loop receptors are activated with emphasis on the best studied nicotinic acetylcholine receptors (nAChRs). With a combination of affinity labeling, mutagenesis, electrophysiology, kinetic modeling, electron microscopy (EM), and crystal structure analysis, the allosteric activation mechanism is emerging. Specifically, the binding domain and gating domain are interconnected by an allosteric activation network. Agonist binding induces conformational changes, resulting in the rotation of a β sheet of amino-terminal domain and outward movement of loop 2, loop F, and cys-loop, which are coupled to the M2-M3 linker to pull the channel to open. However, there are still some controversies about the movement of the channel-lining domain M2. Nine angstrom resolution EM structure of a nAChR imaged in the open state suggests that channel opening is the result of rotation of the M2 domain. In contrast, recent crystal structures of bacterial homologues of the cys-loop receptor family in apparently open state have implied an M2 tilting model with pore dilation and quaternary twist of the whole pentameric receptor. An elegant study of the nAChR using protonation scanning of M2 domain supports a similar pore dilation activation mechanism with minimal rotation of M2. This remains to be validated with other approaches including high resolution structure determination of the mammalian cys-loop receptors in the open state.

  19. Bioinformatic scaling of allosteric interactions in biomedical isozymes

    Science.gov (United States)

    Phillips, J. C.

    2016-09-01

    Allosteric (long-range) interactions can be surprisingly strong in proteins of biomedical interest. Here we use bioinformatic scaling to connect prior results on nonsteroidal anti-inflammatory drugs to promising new drugs that inhibit cancer cell metabolism. Many parallel features are apparent, which explain how even one amino acid mutation, remote from active sites, can alter medical results. The enzyme twins involved are cyclooxygenase (aspirin) and isocitrate dehydrogenase (IDH). The IDH results are accurate to 1% and are overdetermined by adjusting a single bioinformatic scaling parameter. It appears that the final stage in optimizing protein functionality may involve leveling of the hydrophobic limits of the arms of conformational hydrophilic hinges.

  20. Allosteric modulators of the hERG K{sup +} channel

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Zhiyi, E-mail: z.yu@lacdr.leidenuniv.nl; Klaasse, Elisabeth, E-mail: elisabethklaasse@hotmail.com; Heitman, Laura H., E-mail: l.h.heitman@lacdr.leidenuniv.nl; IJzerman, Adriaan P., E-mail: ijzerman@lacdr.leidenuniv.nl

    2014-01-01

    Drugs that block the cardiac K{sup +} channel encoded by the human ether-à-go-go gene (hERG) have been associated with QT interval prolongation leading to proarrhythmia, and in some cases, sudden cardiac death. Because of special structural features of the hERG K{sup +} channel, it has become a promiscuous target that interacts with pharmaceuticals of widely varying chemical structures and a reason for concern in the pharmaceutical industry. The structural diversity suggests that multiple binding sites are available on the channel with possible allosteric interactions between them. In the present study, three reference compounds and nine compounds of a previously disclosed series were evaluated for their allosteric effects on the binding of [{sup 3}H]astemizole and [{sup 3}H]dofetilide to the hERG K{sup +} channel. LUF6200 was identified as an allosteric inhibitor in dissociation assays with both radioligands, yielding similar EC{sub 50} values in the low micromolar range. However, potassium ions increased the binding of the two radioligands in a concentration-dependent manner, and their EC{sub 50} values were not significantly different, indicating that potassium ions behaved as allosteric enhancers. Furthermore, addition of potassium ions resulted in a concentration-dependent leftward shift of the LUF6200 response curve, suggesting positive cooperativity and distinct allosteric sites for them. In conclusion, our investigations provide evidence for allosteric modulation of the hERG K{sup +} channel, which is discussed in the light of findings on other ion channels. - Highlights: • Allosteric modulators on the hERG K{sup +} channel were evaluated in binding assays. • LUF6200 was identified as a potent allosteric inhibitor. • Potassium ions were found to behave as allosteric enhancers. • Positive cooperativity and distinct allosteric sites for them were proposed.

  1. Structural Analysis of Iac Repressor Bound to Allosteric Effectors

    Energy Technology Data Exchange (ETDEWEB)

    Daber,R.; Stayrook, S.; Rosenberg, A.; Lewis, M.

    2007-01-01

    The lac operon is a model system for understanding how effector molecules regulate transcription and are necessary for allosteric transitions. The crystal structures of the lac repressor bound to inducer and anti-inducer molecules provide a model for how these small molecules can modulate repressor function. The structures of the apo repressor and the repressor bound to effector molecules are compared in atomic detail. All effectors examined here bind to the repressor in the same location and are anchored to the repressor through hydrogen bonds to several hydroxyl groups of the sugar ring. Inducer molecules form a more extensive hydrogen-bonding network compared to anti-inducers and neutral effector molecules. The structures of these effector molecules suggest that the O6 hydroxyl on the galactoside is essential for establishing a water-mediated hydrogen bonding network that bridges the N-terminal and C-terminal sub-domains. The altered hydrogen bonding can account in part for the different structural conformations of the repressor, and is vital for the allosteric transition.

  2. Differentiating a Ligand's Chemical Requirements for Allosteric Interactions from Those for Protein Binding. Phenylalanine Inhibition of Pyruvate Kinase

    International Nuclear Information System (INIS)

    The isoform of pyruvate kinase from brain and muscle of mammals (M1-PYK) is allosterically inhibited by phenylalanine. Initial observations in this model allosteric system indicate that Ala binds competitively with Phe, but elicits a minimal allosteric response. Thus, the allosteric ligand of this system must have requirements for eliciting an allosteric response in addition to the requirements for binding. Phe analogues have been used to dissect what chemical properties of Phe are responsible for eliciting the allosteric response. We first demonstrate that the L-2-aminopropanaldehyde substructure of the amino acid ligand is primarily responsible for binding to M1-PYK. Since the allosteric response to Ala is minimal and linear addition of methyl groups beyond the -carbon increase the magnitude of the allosteric response, we conclude that moieties beyond the -carbon are primarily responsible for allostery. Instead of an all-or-none mechanism of allostery, these findings support the idea that the bulk of the hydrophobic side chain, but not the aromatic nature, is the primary determinant of the magnitude of the observed allosteric inhibition. The use of these results to direct structural studies has resulted in a 1.65 Angstroms structure of M1-PYK with Ala bound. The coordination of Ala in the allosteric amino acid binding site confirms the binding role of the L-2-aminopropanaldehyde substructure of the ligand. Collectively, this study confirms that a ligand can have chemical regions specific for eliciting the allosteric signal in addition to the chemical regions necessary for binding

  3. Communicating up

    Science.gov (United States)

    Lum, Lydia

    2013-01-01

    Chief communicators at many U.S. institutions are interested in forging closer ties with governing boards. Proponents say such relationships can increase board trust and confidence in communicators before a crisis occurs, making it easier to manage the institution's reputation and limit negative publicity when one does. At some institutions, such…

  4. Virus assembly and maturation: auto-regulation through allosteric molecular switches.

    Science.gov (United States)

    Domitrovic, Tatiana; Movahed, Navid; Bothner, Brian; Matsui, Tsutomu; Wang, Qiu; Doerschuk, Peter C; Johnson, John E

    2013-05-13

    We generalize the concept of allostery from the traditional non-active-site control of enzymes to virus maturation. Virtually, all animal viruses transition from a procapsid noninfectious state to a mature infectious state. The procapsid contains an encoded chemical program that is executed following an environmental cue. We developed an exceptionally accessible virus system for the study of the activators of maturation and the downstream consequences that result in particle stability and infectivity. Nudaurelia capensis omega virus (NωV) is a T=4 icosahedral virus that undergoes a dramatic maturation in which the 490-Å spherical procapsid condenses to a 400-Å icosahedral-shaped capsid with associated specific auto-proteolysis and stabilization. Employing X-ray crystallography, time-resolved electron cryo-microscopy and hydrogen/deuterium exchange as well as biochemistry, it was possible to define the mechanisms of allosteric communication among the four quasi-equivalent subunits in the icosahedral asymmetric unit. These gene products undergo proteolysis at different rates, dependent on quaternary structure environment, while particle stability is conferred globally following only a few local subunit transitions. We show that there is a close similarity between the concepts of tensegrity (associated with geodesic domes and mechanical engineering) and allostery (associated with biochemical control mechanisms). PMID:23485419

  5. Structural insights into Ca(2+)-activated long-range allosteric channel gating of RyR1.

    Science.gov (United States)

    Wei, Risheng; Wang, Xue; Zhang, Yan; Mukherjee, Saptarshi; Zhang, Lei; Chen, Qiang; Huang, Xinrui; Jing, Shan; Liu, Congcong; Li, Shuang; Wang, Guangyu; Xu, Yaofang; Zhu, Sujie; Williams, Alan J; Sun, Fei; Yin, Chang-Cheng

    2016-09-01

    Ryanodine receptors (RyRs) are a class of giant ion channels with molecular mass over 2.2 mega-Daltons. These channels mediate calcium signaling in a variety of cells. Since more than 80% of the RyR protein is folded into the cytoplasmic assembly and the remaining residues form the transmembrane domain, it has been hypothesized that the activation and regulation of RyR channels occur through an as yet uncharacterized long-range allosteric mechanism. Here we report the characterization of a Ca(2+)-activated open-state RyR1 structure by cryo-electron microscopy. The structure has an overall resolution of 4.9 Å and a resolution of 4.2 Å for the core region. In comparison with the previously determined apo/closed-state structure, we observed long-range allosteric gating of the channel upon Ca(2+) activation. In-depth structural analyses elucidated a novel channel-gating mechanism and a novel ion selectivity mechanism of RyR1. Our work not only provides structural insights into the molecular mechanisms of channel gating and regulation of RyRs, but also sheds light on structural basis for channel-gating and ion selectivity mechanisms for the six-transmembrane-helix cation channel family. PMID:27573175

  6. Allosteric and orthosteric sites in CC chemokine receptor (CCR5), a chimeric receptor approach

    DEFF Research Database (Denmark)

    Thiele, Stefanie; Steen, Anne; Jensen, Pia C;

    2011-01-01

    -allosteric molecules. A chimera was successfully constructed between CCR5 and the closely related CCR2 by transferring all extracellular regions of CCR2 to CCR5, i.e. a Trojan horse that resembles CCR2 extracellularly but signals through a CCR5 transmembrane unit. The chimera bound CCR2 (CCL2 and CCL7), but not CCR5...... preserved, the allosteric enhancement of chemokine binding was disrupted. In summary, the Trojan horse chimera revealed that orthosteric and allosteric sites could be structurally separated and still act together with transmission of agonism and antagonism across the different receptor units....

  7. Ago-allosteric modulation and other types of allostery in dimeric 7TM receptors

    DEFF Research Database (Denmark)

    Schwartz, Thue W; Holst, Birgitte

    concept for 7TM receptors, it is proposed that the ago-allosteric modulators bind in the orthosteric binding site, but-importantly-in the "other" or allosteric protomer of the dimer. Hereby, they can act both as additive co-agonists, and through intermolecular cooperative effects between the protomers......, they may influence the potency of the endogenous agonist. It is of interest that at least some endogenous agonists can only occupy one protomer of a dimeric 7TM receptor complex at a time and thereby they leave the orthosteric binding site in the allosteric protomer free, potentially for binding of...

  8. Structure of N-acetyl-L-glutamate synthase/kinase from Maricaulis maris with the allosteric inhibitor L-arginine bound.

    Science.gov (United States)

    Zhao, Gengxiang; Haskins, Nantaporn; Jin, Zhongmin; M Allewell, Norma; Tuchman, Mendel; Shi, Dashuang

    2013-08-01

    Maricaulis maris N-acetylglutamate synthase/kinase (mmNAGS/K) catalyzes the first two steps in L-arginine biosynthesis and has a high degree of sequence and structural homology to human N-acetylglutamate synthase, a regulator of the urea cycle. The synthase activity of both mmNAGS/K and human NAGS are regulated by L-arginine, although L-arginine is an allosteric inhibitor of mmNAGS/K, but an activator of human NAGS. To investigate the mechanism of allosteric inhibition of mmNAGS/K by L-arginine, we have determined the structure of the mmNAGS/K complexed with L-arginine at 2.8 Å resolution. In contrast to the structure of mmNAGS/K in the absence of L-arginine where there are conformational differences between the four subunits in the asymmetric unit, all four subunits in the L-arginine liganded structure have very similar conformations. In this conformation, the AcCoA binding site in the N-acetyltransferase (NAT) domain is blocked by a loop from the amino acid kinase (AAK) domain, as a result of a domain rotation that occurs when L-arginine binds. This structural change provides an explanation for the allosteric inhibition of mmNAGS/K and related enzymes by L-arginine. The allosterically regulated mechanism for mmNAGS/K differs significantly from that for Neisseria gonorrhoeae NAGS (ngNAGS). To define the active site, several residues near the putative active site were mutated and their activities determined. These experiments identify roles for Lys356, Arg386, Asn391 and Tyr397 in the catalytic mechanism. PMID:23850694

  9. Coarse-Grained Molecular Simulations of Allosteric Cooperativity

    CERN Document Server

    Nandigrami, Prithviraj

    2015-01-01

    Interactions between a protein and a ligand are often accompanied by a redistribution of the population of thermally accessible conformations. This dynamic response of the protein's functional energy landscape enables a protein to modulate binding affinities and control binding sensitivity to ligand concentration. In this paper, we investigate the structural origins of binding affinity and allosteric cooperativity of binding two calcium ions to each domain of calmodulin (CaM) through simulations of a simple coarse-grained model. In this model, the protein's conformational transitions between open and closed conformational ensembles are simulated explicitly and ligand binding and unbinding is treated implicitly at the mean field level. Ligand binding is cooperative because the binding sites are coupled through a shift in the dominant conformational ensemble upon binding. The classic Monod-Wyman-Changeux model of allostery with appropriate binding free energy to the open and closed ensembles accurately describe...

  10. Engineering an allosteric transcription factor to respond to new ligands.

    Science.gov (United States)

    Taylor, Noah D; Garruss, Alexander S; Moretti, Rocco; Chan, Sum; Arbing, Mark A; Cascio, Duilio; Rogers, Jameson K; Isaacs, Farren J; Kosuri, Sriram; Baker, David; Fields, Stanley; Church, George M; Raman, Srivatsan

    2016-02-01

    Genetic regulatory proteins inducible by small molecules are useful synthetic biology tools as sensors and switches. Bacterial allosteric transcription factors (aTFs) are a major class of regulatory proteins, but few aTFs have been redesigned to respond to new effectors beyond natural aTF-inducer pairs. Altering inducer specificity in these proteins is difficult because substitutions that affect inducer binding may also disrupt allostery. We engineered an aTF, the Escherichia coli lac repressor, LacI, to respond to one of four new inducer molecules: fucose, gentiobiose, lactitol and sucralose. Using computational protein design, single-residue saturation mutagenesis or random mutagenesis, along with multiplex assembly, we identified new variants comparable in specificity and induction to wild-type LacI with its inducer, isopropyl β-D-1-thiogalactopyranoside (IPTG). The ability to create designer aTFs will enable applications including dynamic control of cell metabolism, cell biology and synthetic gene circuits. PMID:26689263

  11. Orthosteric and Allosteric Regulation in Trypsin-Like Peptidases

    DEFF Research Database (Denmark)

    Kromann-Tofting, Tobias

    2015-01-01

    Trypsin-like serine peptidases play an important role in many physiological and pathophysiological processes, the latter including cardiovascular diseases and cancer. Binding of natural ligands to functional sites on the peptidase surface balances the level of activity and substrate specificity of...... peptidase and allosterically modulate the function of the active site, represents two important activity-regulating mechanisms in trypsin-like serine peptidases. Development of specific orthosteric agents as therapeutics is a challenge due to similar active site topology within the trypsin-like serine...... peptidase. The thesis describes how X-ray crystal structure analysis and biochemical analysis were used to demonstrate new concepts for orthosteric regulation of activity in the trypsin-like serine peptidase urokinase-type plasminogen activator (uPA), studying two types of orthosteric agents, namely cyclic...

  12. Architecture and Co-Evolution of Allosteric Materials

    CERN Document Server

    Yan, Le; Brito, Carolina; Wyart, Matthieu

    2016-01-01

    We introduce a numerical scheme to evolve functional materials that can accomplish a specified mechanical task. In this scheme, the number of solutions, their spatial architectures and the correlations among them can be computed. As an example, we consider an "allosteric" task, which requires the material to respond specifically to a stimulus at a distant active site. We find that functioning materials evolve a less-constrained trumpet-shaped region connecting the stimulus and active sites and that the amplitude of the elastic response varies non-monotonically along the trumpet. As previously shown for some proteins, we find that correlations appearing during evolution alone are sufficient to identify key aspects of this design. Finally, we show that the success of this architecture stems from the emergence of soft edge modes recently found to appear near the surface of marginally connected materials. Overall, our in silico evolution experiment offers a new window to study the relationship between structure, ...

  13. Structure-based network analysis of activation mechanisms in the ErbB family of receptor tyrosine kinases: the regulatory spine residues are global mediators of structural stability and allosteric interactions.

    Directory of Open Access Journals (Sweden)

    Kevin A James

    Full Text Available The ErbB protein tyrosine kinases are among the most important cell signaling families and mutation-induced modulation of their activity is associated with diverse functions in biological networks and human disease. We have combined molecular dynamics simulations of the ErbB kinases with the protein structure network modeling to characterize the reorganization of the residue interaction networks during conformational equilibrium changes in the normal and oncogenic forms. Structural stability and network analyses have identified local communities integrated around high centrality sites that correspond to the regulatory spine residues. This analysis has provided a quantitative insight to the mechanism of mutation-induced "superacceptor" activity in oncogenic EGFR dimers. We have found that kinase activation may be determined by allosteric interactions between modules of structurally stable residues that synchronize the dynamics in the nucleotide binding site and the αC-helix with the collective motions of the integrating αF-helix and the substrate binding site. The results of this study have pointed to a central role of the conserved His-Arg-Asp (HRD motif in the catalytic loop and the Asp-Phe-Gly (DFG motif as key mediators of structural stability and allosteric communications in the ErbB kinases. We have determined that residues that are indispensable for kinase regulation and catalysis often corresponded to the high centrality nodes within the protein structure network and could be distinguished by their unique network signatures. The optimal communication pathways are also controlled by these nodes and may ensure efficient allosteric signaling in the functional kinase state. Structure-based network analysis has quantified subtle effects of ATP binding on conformational dynamics and stability of the EGFR structures. Consistent with the NMR studies, we have found that nucleotide-induced modulation of the residue interaction networks is not

  14. Allosteric Optical Control of a Class B G-Protein-Coupled Receptor.

    Science.gov (United States)

    Broichhagen, Johannes; Johnston, Natalie R; von Ohlen, Yorrick; Meyer-Berg, Helena; Jones, Ben J; Bloom, Stephen R; Rutter, Guy A; Trauner, Dirk; Hodson, David J

    2016-05-01

    Allosteric regulation promises to open up new therapeutic avenues by increasing drug specificity at G-protein-coupled receptors (GPCRs). However, drug discovery efforts are at present hampered by an inability to precisely control the allosteric site. Herein, we describe the design, synthesis, and testing of PhotoETP, a light-activated positive allosteric modulator of the glucagon-like peptide-1 receptor (GLP-1R), a class B GPCR involved in the maintenance of glucose homeostasis in humans. PhotoETP potentiates Ca(2+) , cAMP, and insulin responses to glucagon-like peptide-1 and its metabolites following illumination of cells with blue light. PhotoETP thus provides a blueprint for the production of small-molecule class B GPCR allosteric photoswitches, and may represent a useful tool for understanding positive cooperativity at the GLP-1R. PMID:27059784

  15. Structure and allosteric effects of low-molecular-weight activators on the protein kinase PDK1

    DEFF Research Database (Denmark)

    Hindie, Valerie; Stroba, Adriana; Zhang, Hua;

    2009-01-01

    Protein phosphorylation transduces a large set of intracellular signals. One mechanism by which phosphorylation mediates signal transduction is by prompting conformational changes in the target protein or interacting proteins. Previous work described an allosteric site mediating phosphorylation-d...

  16. Positive allosteric feedback regulation of the stringent response enzyme RelA by its product

    OpenAIRE

    Shyp, Viktoriya; Tankov, Stoyan; Ermakov, Andrey; Kudrin, Pavel; English, Brian P.; Ehrenberg, Måns; Tenson, Tanel; Elf, Johan; Hauryliuk, Vasili

    2012-01-01

    This report identifies a new mechanism of enzyme activation—positive allosteric regulation by the product—in the context of the bacterial stringent response, which is essential for bacterial adaptation to environmental conditions.

  17. Allosteric Mechanism of Pyruvate Kinase from Leishmania mexicana Uses a Rock and Lock Model*

    OpenAIRE

    Morgan, Hugh P.; McNae, Iain W.; Matthew W Nowicki; Hannaert, Véronique; Michels, Paul A M; Fothergill-Gilmore, Linda A.; Walkinshaw, Malcolm D.

    2010-01-01

    Allosteric regulation provides a rate management system for enzymes involved in many cellular processes. Ligand-controlled regulation is easily recognizable, but the underlying molecular mechanisms have remained elusive. We have obtained the first complete series of allosteric structures, in all possible ligated states, for the tetrameric enzyme, pyruvate kinase, from Leishmania mexicana. The transition between inactive T-state and active R-state is accompanied by a simple symmetrical 6° rigi...

  18. Allosteric Partial Inhibition of Monomeric Proteases. Sulfated Coumarins Induce Regulation, not just Inhibition, of Thrombin

    OpenAIRE

    Stephen Verespy III; Mehta, Akul Y.; Daniel Afosah; Al-Horani, Rami A.; Desai, Umesh R.

    2016-01-01

    Allosteric partial inhibition of soluble, monomeric proteases can offer major regulatory advantages, but remains a concept on paper to date; although it has been routinely documented for receptors and oligomeric proteins. Thrombin, a key protease of the coagulation cascade, displays significant conformational plasticity, which presents an attractive opportunity to discover small molecule probes that induce sub-maximal allosteric inhibition. We synthesized a focused library of some 36 sulfated...

  19. Fumarate analogs act as allosteric inhibitors of the human mitochondrial NAD(P+-dependent malic enzyme.

    Directory of Open Access Journals (Sweden)

    Ju-Yi Hsieh

    Full Text Available Human mitochondrial NAD(P+-dependent malic enzyme (m-NAD(P-ME is allosterically activated by the four-carbon trans dicarboxylic acid, fumarate. Previous studies have suggested that the dicarboxylic acid in a trans conformation around the carbon-carbon double bond is required for the allosteric activation of the enzyme. In this paper, the allosteric effects of fumarate analogs on m-NAD(P-ME are investigated. Two fumarate-insensitive mutants, m-NAD(P-ME_R67A/R91A and m-NAD(P-ME_K57S/E59N/K73E/D102S, as well as c-NADP-ME, were used as the negative controls. Among these analogs, mesaconate, trans-aconitate, monomethyl fumarate and monoethyl fumarate were allosteric activators of the enzyme, while oxaloacetate, diethyl oxalacetate, and dimethyl fumarate were found to be allosteric inhibitors of human m-NAD(P-ME. The IC50 value for diethyl oxalacetate was approximately 2.5 mM. This paper suggests that the allosteric inhibitors may impede the conformational change from open form to closed form and therefore inhibit m-NAD(P-ME enzyme activity.

  20. Comparing allosteric transitions in the domains of calmodulin through coarse-grained simulations

    CERN Document Server

    Nandigrami, Prithviraj

    2015-01-01

    Calmodulin (CaM) is a ubiquitous calcium binding protein consisting of two structurally similar domains with distinct stabilities, binding affinities, and flexibilities. We present coarse grained simulations that suggest the mechanism for the domain's allosteric transitions between the open and closed conformations depend on subtle differences in the folded state topology of the two domains. Throughout a wide temperature range, the simulated transition mechanism of the N-terminal domain (nCaM) follows a two-state transition mechanism while domain opening in the C-terminal domain (cCaM) involves unfolding and refolding of the tertiary structure. The appearance of the unfolded intermediate occurs at a higher temperature in nCaM than it does in cCaM. That is, we find that cCaM unfolds more readily along the transition route than nCaM. Furthermore, unfolding and refolding of the domain significantly slows the domain opening and closing rates of cCaM, a distinct scenario which can potentially influence the mechani...

  1. Allosteric coupling from G protein to the agonist-binding pocket in GPCRs.

    Science.gov (United States)

    DeVree, Brian T; Mahoney, Jacob P; Vélez-Ruiz, Gisselle A; Rasmussen, Soren G F; Kuszak, Adam J; Edwald, Elin; Fung, Juan-Jose; Manglik, Aashish; Masureel, Matthieu; Du, Yang; Matt, Rachel A; Pardon, Els; Steyaert, Jan; Kobilka, Brian K; Sunahara, Roger K

    2016-07-01

    G-protein-coupled receptors (GPCRs) remain the primary conduit by which cells detect environmental stimuli and communicate with each other. Upon activation by extracellular agonists, these seven-transmembrane-domain-containing receptors interact with heterotrimeric G proteins to regulate downstream second messenger and/or protein kinase cascades. Crystallographic evidence from a prototypic GPCR, the β2-adrenergic receptor (β2AR), in complex with its cognate G protein, Gs, has provided a model for how agonist binding promotes conformational changes that propagate through the GPCR and into the nucleotide-binding pocket of the G protein α-subunit to catalyse GDP release, the key step required for GTP binding and activation of G proteins. The structure also offers hints about how G-protein binding may, in turn, allosterically influence ligand binding. Here we provide functional evidence that G-protein coupling to the β2AR stabilizes a ‘closed’ receptor conformation characterized by restricted access to and egress from the hormone-binding site. Surprisingly, the effects of G protein on the hormone-binding site can be observed in the absence of a bound agonist, where G-protein coupling driven by basal receptor activity impedes the association of agonists, partial agonists, antagonists and inverse agonists. The ability of bound ligands to dissociate from the receptor is also hindered, providing a structural explanation for the G-protein-mediated enhancement of agonist affinity, which has been observed for many GPCR–G-protein pairs. Our data also indicate that, in contrast to agonist binding alone, coupling of a G protein in the absence of an agonist stabilizes large structural changes in a GPCR. The effects of nucleotide-free G protein on ligand-binding kinetics are shared by other members of the superfamily of GPCRs, suggesting that a common mechanism may underlie G-protein-mediated enhancement of agonist affinity. PMID:27362234

  2. Computational Investigation on the Allosteric Modulation of Androgen Receptor

    Institute of Scientific and Technical Information of China (English)

    OU Min-Rui; LI Jun-Qian

    2012-01-01

    Androgens have similar structures with different biological activities. To identify molecular determinants responsible for the activity difference, we have docked six steroidal androgens to the binding site or the surface of androgen receptor by using molecular docking with computational investigation. The energy was calculated respectively based on the QM (quantum mechanics) and MM (molecular mechanics) methods. The result shows that the allosteric modulation of androgen receptor plays an important role in the binding process between androgens and receptor. The open state receptor is less stable than the close state one, but the latter is more favorable for binding with androgens. It is worthy of note that when the androgen receptors binding or without binding with androgen are in close state, they are difficult to return to their open state. This phenomenon is an exception of the well known two-state model theory in which the two states are reversible. Whether the internal of close state androgen receptor has a combination of androgen or not, the androgen receptor surface can be combined with another androgen, and their surface binding energies could be very close. The result is consistent with the experimental observations, but this phenomenon of continuous combination from open state is also an exception of the two-state model theory.

  3. Allosteric modulation of metabotropic glutamate receptors by chloride ions.

    Science.gov (United States)

    Tora, Amélie S; Rovira, Xavier; Dione, Ibrahima; Bertrand, Hugues-Olivier; Brabet, Isabelle; De Koninck, Yves; Doyon, Nicolas; Pin, Jean-Philippe; Acher, Francine; Goudet, Cyril

    2015-10-01

    Metabotropic glutamate receptors (mGluRs) play key roles in the modulation of many synapses. Chloride (Cl(-)) is known to directly bind and regulate the function of different actors of neuronal activity, and several studies have pointed to the possible modulation of mGluRs by Cl(-). Herein, we demonstrate that Cl(-) behaves as a positive allosteric modulator of mGluRs. For example, whereas glutamate potency was 3.08 ± 0.33 μM on metabotropic glutamate (mGlu) 4 receptors in high-Cl(-) buffer, signaling activity was almost abolished in low Cl(-) in cell-based assays. Cl(-) potency was 78.6 ± 3.5 mM. Cl(-) possesses a high positive cooperativity with glutamate (Hill slope ≈6 on mGlu4), meaning that small variations in [Cl(-)] lead to large variations in glutamate action. Using molecular modeling and mutagenesis, we have identified 2 well-conserved Cl(-) binding pockets in the extracellular domain of mGluRs. Moreover, modeling of activity-dependent Cl(-) variations at GABAergic synapses suggests that these variations may be compatible with a dynamic modulation of the most sensitive mGluRs present in these synapses. Taken together, these data reveal a necessary role of Cl(-) for the glutamate activation of many mGluRs. Exploiting Cl(-) binding pockets may yield to the development of innovative regulators of mGluR activity. PMID:26116702

  4. Allosteric receptor activation by the plant peptide hormone phytosulfokine.

    Science.gov (United States)

    Wang, Jizong; Li, Hongju; Han, Zhifu; Zhang, Heqiao; Wang, Tong; Lin, Guangzhong; Chang, Junbiao; Yang, Weicai; Chai, Jijie

    2015-09-10

    Phytosulfokine (PSK) is a disulfated pentapeptide that has a ubiquitous role in plant growth and development. PSK is perceived by its receptor PSKR, a leucine-rich repeat receptor kinase (LRR-RK). The mechanisms underlying the recognition of PSK, the activation of PSKR and the identity of the components downstream of the initial binding remain elusive. Here we report the crystal structures of the extracellular LRR domain of PSKR in free, PSK- and co-receptor-bound forms. The structures reveal that PSK interacts mainly with a β-strand from the island domain of PSKR, forming an anti-β-sheet. The two sulfate moieties of PSK interact directly with PSKR, sensitizing PSKR recognition of PSK. Supported by biochemical, structural and genetic evidence, PSK binding enhances PSKR heterodimerization with the somatic embryogenesis receptor-like kinases (SERKs). However, PSK is not directly involved in PSKR-SERK interaction but stabilizes PSKR island domain for recruitment of a SERK. Our data reveal the structural basis for PSKR recognition of PSK and allosteric activation of PSKR by PSK, opening up new avenues for the design of PSKR-specific small molecules. PMID:26308901

  5. Inversion of allosteric effect of arginine on N-acetylglutamate synthase, a molecular marker for evolution of tetrapods

    Directory of Open Access Journals (Sweden)

    Cabrera-Luque Juan

    2008-09-01

    Full Text Available Abstract Background The efficient conversion of ammonia, a potent neurotoxin, into non-toxic metabolites was an essential adaptation that allowed animals to move from the aquatic to terrestrial biosphere. The urea cycle converts ammonia into urea in mammals, amphibians, turtles, snails, worms and many aquatic animals and requires N-acetylglutamate (NAG, an essential allosteric activator of carbamylphosphate synthetase I (CPSI in mammals and amphibians, and carbamylphosphate synthetase III (CPSIII in fish and invertebrates. NAG-dependent CPSI and CPSIII catalyze the formation of carbamylphosphate in the first and rate limiting step of ureagenesis. NAG is produced enzymatically by N-acetylglutamate synthase (NAGS, which is also found in bacteria and plants as the first enzyme of arginine biosynthesis. Arginine is an allosteric inhibitor of microbial and plant NAGS, and allosteric activator of mammalian NAGS. Results Information from mutagenesis studies of E. coli and P. aeruginosa NAGS was combined with structural information from the related bacterial N-acetylglutamate kinases to identify four residues in mammalian NAGS that interact with arginine. Substitutions of these four residues were engineered in mouse NAGS and into the vertebrate-like N-acetylglutamate synthase-kinase (NAGS-K of Xanthomonas campestris, which is inhibited by arginine. All mutations resulted in arginine losing the ability to activate mouse NAGS, and inhibit X. campestris NAGS-K. To examine at what point in evolution inversion of arginine effect on NAGS occur, we cloned NAGS from fish and frogs and examined the arginine response of their corresponding proteins. Fish NAGS were partially inhibited by arginine and frog NAGS were activated by arginine. Conclusion Difference in arginine effect on bacterial and mammalian NAGS most likely stems from the difference in the type of conformational change triggered by arginine binding to these proteins. The change from arginine

  6. Positive cooperativity of acetylcholine and other agonists with allosteric ligands on muscarinic acetylcholine receptors.

    Science.gov (United States)

    Jakubík, J; Bacáková, L; El-Fakahany, E E; Tucek, S

    1997-07-01

    It is well known that allosteric modulators of muscarinic acetylcholine receptors can both diminish and increase the affinity of receptors for their antagonists. We investigated whether the allosteric modulators can also increase the affinity of receptors for their agonists. Twelve agonists and five allosteric modulators were tested in experiments on membranes of CHO cells that had been stably transfected with genes for the M1-M4 receptor subtypes. Allosterically induced changes in the affinities for agonists were computed from changes in the ability of a fixed concentration of each agonist to compete with [3H]N-methylscopolamine for the binding to the receptors in the absence and the presence of varying concentrations of allosteric modulators. The effects of allosteric modulators varied greatly depending on the agonists and the subtypes of receptors. The affinity for acetylcholine was augmented by (-)-eburnamonine on the M2 and M4 receptors and by brucine on the M1 and M3 receptors. Brucine also enhanced the affinities for carbachol, bethanechol, furmethide, methylfurmethide, pilocarpine, 3-(3-pentylthio-1,2,5-thiadiazol-4-yl)-1,2,5,6-tetrahydro-1- methylpyridine (pentylthio-TZTP), oxotremorine-M, and McN-A-343 on the M1, M3, and M4 receptors, for pentylthio-TZTP on the M2 receptors, and for arecoline on the M3 receptors. (-)-Eburnamonine enhanced the affinities for carbachol, bethanechol, furmethide, methylfurmethide, pentylthio-TZTP, pilocarpine, oxotremorine and oxotremorine-M on the M2 receptors and for pilocarpine on the M4 receptors. Vincamine, strychnine, and alcuronium displayed fewer positive allosteric interactions with the agonists, but each allosteric modulator displayed positive cooperativity with at least one agonist on at least one muscarinic receptor subtype. The highest degrees of positive cooperativity were observed between (-)-eburnamonine and pilocarpine and (-)-eburnamonine and oxotremorine-M on the M2 receptors (25- and 7-fold increases in

  7. Chemical shift imprint of intersubunit communication in a symmetric homodimer.

    Science.gov (United States)

    Falk, Bradley T; Sapienza, Paul J; Lee, Andrew L

    2016-08-23

    Allosteric communication is critical for protein function and cellular homeostasis, and it can be exploited as a strategy for drug design. However, unlike many protein-ligand interactions, the structural basis for the long-range communication that underlies allostery is not well understood. This lack of understanding is most evident in the case of classical allostery, in which a binding event in one protomer is sensed by a second symmetric protomer. A primary reason why study of interdomain signaling is challenging in oligomeric proteins is the difficulty in characterizing intermediate, singly bound species. Here, we use an NMR approach to isolate and characterize a singly ligated state ("lig1") of a homodimeric enzyme that is otherwise obscured by rapid exchange with apo and saturated forms. Mixed labeled dimers were prepared that simultaneously permit full population of the lig1 state and isotopic labeling of either protomer. Direct visualization of peaks from lig1 yielded site-specific ligand-state multiplets that provide a convenient format for assessing mechanisms of intersubunit communication from a variety of NMR measurements. We demonstrate this approach on thymidylate synthase from Escherichia coli, a homodimeric enzyme known to be half-the-sites reactive. Resolving the dUMP1 state shows that active site communication occurs not upon the first dUMP binding, but upon the second. Surprisingly, for many sites, dUMP1 peaks are found beyond the limits set by apo and dUMP2 peaks, indicating that binding the first dUMP pushes the enzyme ensemble to further conformational extremes than the apo or saturated forms. The approach used here should be generally applicable to homodimers. PMID:27466406

  8. Structural basis for modulation of a G-protein-coupled receptor by allosteric drugs

    Science.gov (United States)

    Dror, Ron O.; Green, Hillary F.; Valant, Celine; Borhani, David W.; Valcourt, James R.; Pan, Albert C.; Arlow, Daniel H.; Canals, Meritxell; Lane, J. Robert; Rahmani, Raphaël; Baell, Jonathan B.; Sexton, Patrick M.; Christopoulos, Arthur; Shaw, David E.

    2013-11-01

    The design of G-protein-coupled receptor (GPCR) allosteric modulators, an active area of modern pharmaceutical research, has proved challenging because neither the binding modes nor the molecular mechanisms of such drugs are known. Here we determine binding sites, bound conformations and specific drug-receptor interactions for several allosteric modulators of the M2 muscarinic acetylcholine receptor (M2 receptor), a prototypical family A GPCR, using atomic-level simulations in which the modulators spontaneously associate with the receptor. Despite substantial structural diversity, all modulators form cation-π interactions with clusters of aromatic residues in the receptor extracellular vestibule, approximately 15Å from the classical, `orthosteric' ligand-binding site. We validate the observed modulator binding modes through radioligand binding experiments on receptor mutants designed, on the basis of our simulations, either to increase or to decrease modulator affinity. Simulations also revealed mechanisms that contribute to positive and negative allosteric modulation of classical ligand binding, including coupled conformational changes of the two binding sites and electrostatic interactions between ligands in these sites. These observations enabled the design of chemical modifications that substantially alter a modulator's allosteric effects. Our findings thus provide a structural basis for the rational design of allosteric modulators targeting muscarinic and possibly other GPCRs.

  9. Molecular Dynamics Simulations Reveal the Mechanisms of Allosteric Activation of Hsp90 by Designed Ligands

    Science.gov (United States)

    Vettoretti, Gerolamo; Moroni, Elisabetta; Sattin, Sara; Tao, Jiahui; Agard, David A.; Bernardi, Anna; Colombo, Giorgio

    2016-04-01

    Controlling biochemical pathways through chemically designed modulators may provide novel opportunities to develop therapeutic drugs and chemical tools. The underlying challenge is to design new molecular entities able to act as allosteric chemical switches that selectively turn on/off functions by modulating the conformational dynamics of their target protein. We examine the origins of the stimulation of ATPase and closure kinetics in the molecular chaperone Hsp90 by allosteric modulators through atomistic molecular dynamics (MD) simulations and analysis of protein-ligand interactions. In particular, we focus on the cross-talk between allosteric ligands and protein conformations and its effect on the dynamic properties of the chaperone’s active state. We examine the impact of different allosteric modulators on the stability, structural and internal dynamics properties of Hsp90 closed state. A critical aspect of this study is the development of a quantitative model that correlates Hsp90 activation to the presence of a certain compound, making use of information on the dynamic adaptation of protein conformations to the presence of the ligand, which allows to capture conformational states relevant in the activation process. We discuss the implications of considering the conformational dialogue between allosteric ligands and protein conformations for the design of new functional modulators.

  10. Allosteric inhibition of the NS2B-NS3 protease from dengue virus.

    Science.gov (United States)

    Yildiz, Muslum; Ghosh, Sumana; Bell, Jeffrey A; Sherman, Woody; Hardy, Jeanne A

    2013-12-20

    Dengue virus is the flavivirus that causes dengue fever, dengue hemorrhagic disease, and dengue shock syndrome, which are currently increasing in incidence worldwide. Dengue virus protease (NS2B-NS3pro) is essential for dengue virus infection and is thus a target of therapeutic interest. To date, attention has focused on developing active-site inhibitors of NS2B-NS3pro. The flat and charged nature of the NS2B-NS3pro active site may contribute to difficulties in developing inhibitors and suggests that a strategy of identifying allosteric sites may be useful. We report an approach that allowed us to scan the NS2B-NS3pro surface by cysteine mutagenesis and use cysteine reactive probes to identify regions of the protein that are susceptible to allosteric inhibition. This method identified a new allosteric site utilizing a circumscribed panel of just eight cysteine variants and only five cysteine reactive probes. The allosterically sensitive site is centered at Ala125, between the 120s loop and the 150s loop. The crystal structures of WT and modified NS2B-NS3pro demonstrate that the 120s loop is flexible. Our work suggests that binding at this site prevents a conformational rearrangement of the NS2B region of the protein, which is required for activation. Preventing this movement locks the protein into the open, inactive conformation, suggesting that this site may be useful in the future development of therapeutic allosteric inhibitors. PMID:24164286

  11. Allosteric inhibition of Aurora-A kinase by a synthetic vNAR domain.

    Science.gov (United States)

    Burgess, Selena G; Oleksy, Arkadiusz; Cavazza, Tommaso; Richards, Mark W; Vernos, Isabelle; Matthews, David; Bayliss, Richard

    2016-07-01

    The vast majority of clinically approved protein kinase inhibitors target the ATP-binding pocket directly. Consequently, many inhibitors have broad selectivity profiles and most have significant off-target effects. Allosteric inhibitors are generally more selective, but are difficult to identify because allosteric binding sites are often unknown or poorly characterized. Aurora-A is activated through binding of TPX2 to an allosteric site on the kinase catalytic domain, and this knowledge could be exploited to generate an inhibitor. Here, we generated an allosteric inhibitor of Aurora-A kinase based on a synthetic, vNAR single domain scaffold, vNAR-D01. Biochemical studies and a crystal structure of the Aurora-A/vNAR-D01 complex show that the vNAR domain overlaps with the TPX2 binding site. In contrast with the binding of TPX2, which stabilizes an active conformation of the kinase, binding of the vNAR domain stabilizes an inactive conformation, in which the αC-helix is distorted, the canonical Lys-Glu salt bridge is broken and the regulatory (R-) spine is disrupted by an additional hydrophobic side chain from the activation loop. These studies illustrate how single domain antibodies can be used to characterize the regulatory mechanisms of kinases and provide a rational basis for structure-guided design of allosteric Aurora-A kinase inhibitors. PMID:27411893

  12. Allosteric Partial Inhibition of Monomeric Proteases. Sulfated Coumarins Induce Regulation, not just Inhibition, of Thrombin.

    Science.gov (United States)

    Verespy Iii, Stephen; Mehta, Akul Y; Afosah, Daniel; Al-Horani, Rami A; Desai, Umesh R

    2016-01-01

    Allosteric partial inhibition of soluble, monomeric proteases can offer major regulatory advantages, but remains a concept on paper to date; although it has been routinely documented for receptors and oligomeric proteins. Thrombin, a key protease of the coagulation cascade, displays significant conformational plasticity, which presents an attractive opportunity to discover small molecule probes that induce sub-maximal allosteric inhibition. We synthesized a focused library of some 36 sulfated coumarins to discover two agents that display sub-maximal efficacy (~50%), high potency (150-fold). Michaelis-Menten, competitive inhibition, and site-directed mutagenesis studies identified exosite 2 as the site of binding for the most potent sulfated coumarin. Stern-Volmer quenching of active site-labeled fluorophore suggested that the allosteric regulators induce intermediate structural changes in the active site as compared to those that display ~80-100% efficacy. Antithrombin inactivation of thrombin was impaired in the presence of the sulfated coumarins suggesting that allosteric partial inhibition arises from catalytic dysfunction of the active site. Overall, sulfated coumarins represent first-in-class, sub-maximal inhibitors of thrombin. The probes establish the concept of allosteric partial inhibition of soluble, monomeric proteins. This concept may lead to a new class of anticoagulants that are completely devoid of bleeding. PMID:27053426

  13. A dynamically coupled allosteric network underlies binding cooperativity in Src kinase

    Science.gov (United States)

    Foda, Zachariah H.; Shan, Yibing; Kim, Eric T.; Shaw, David E.; Seeliger, Markus A.

    2015-01-01

    Protein tyrosine kinases are attractive drug targets because many human diseases are associated with the deregulation of kinase activity. However, how the catalytic kinase domain integrates different signals and switches from an active to an inactive conformation remains incompletely understood. Here we identify an allosteric network of dynamically coupled amino acids in Src kinase that connects regulatory sites to the ATP- and substrate-binding sites. Surprisingly, reactants (ATP and peptide substrates) bind with negative cooperativity to Src kinase while products (ADP and phosphopeptide) bind with positive cooperativity. We confirm the molecular details of the signal relay through the allosteric network by biochemical studies. Experiments on two additional protein tyrosine kinases indicate that the allosteric network may be largely conserved among these enzymes. Our work provides new insights into the regulation of protein tyrosine kinases and establishes a potential conduit by which resistance mutations to ATP-competitive kinase inhibitors can affect their activity.

  14. Identifying Allosteric Hotspots with Dynamics: Application to Inter- and Intra-species Conservation.

    Science.gov (United States)

    Clarke, Declan; Sethi, Anurag; Li, Shantao; Kumar, Sushant; Chang, Richard W F; Chen, Jieming; Gerstein, Mark

    2016-05-01

    The rapidly growing volume of data being produced by next-generation sequencing initiatives is enabling more in-depth analyses of conservation than previously possible. Deep sequencing is uncovering disease loci and regions under selective constraint, despite the fact that intuitive biophysical reasons for such constraint are sometimes absent. Allostery may often provide the missing explanatory link. We use models of protein conformational change to identify allosteric residues by finding essential surface pockets and information-flow bottlenecks, and we develop a software tool that enables users to perform this analysis on their own proteins of interest. Though fundamentally 3D-structural in nature, our analysis is computationally fast, thereby allowing us to run it across the PDB and to evaluate general properties of predicted allosteric residues. We find that these tend to be conserved over diverse evolutionary time scales. Finally, we highlight examples of allosteric residues that help explain poorly understood disease-associated variants. PMID:27066750

  15. A dynamically coupled allosteric network underlies binding cooperativity in Src kinase.

    Science.gov (United States)

    Foda, Zachariah H; Shan, Yibing; Kim, Eric T; Shaw, David E; Seeliger, Markus A

    2015-01-01

    Protein tyrosine kinases are attractive drug targets because many human diseases are associated with the deregulation of kinase activity. However, how the catalytic kinase domain integrates different signals and switches from an active to an inactive conformation remains incompletely understood. Here we identify an allosteric network of dynamically coupled amino acids in Src kinase that connects regulatory sites to the ATP- and substrate-binding sites. Surprisingly, reactants (ATP and peptide substrates) bind with negative cooperativity to Src kinase while products (ADP and phosphopeptide) bind with positive cooperativity. We confirm the molecular details of the signal relay through the allosteric network by biochemical studies. Experiments on two additional protein tyrosine kinases indicate that the allosteric network may be largely conserved among these enzymes. Our work provides new insights into the regulation of protein tyrosine kinases and establishes a potential conduit by which resistance mutations to ATP-competitive kinase inhibitors can affect their activity. PMID:25600932

  16. Guanine nucleotide binding to the Bateman domain mediates the allosteric inhibition of eukaryotic IMP dehydrogenases

    Science.gov (United States)

    Buey, Rubén M.; Ledesma-Amaro, Rodrigo; Velázquez-Campoy, Adrián; Balsera, Mónica; Chagoyen, Mónica; de Pereda, José M.; Revuelta, José L.

    2015-11-01

    Inosine-5'-monophosphate dehydrogenase (IMPDH) plays key roles in purine nucleotide metabolism and cell proliferation. Although IMPDH is a widely studied therapeutic target, there is limited information about its physiological regulation. Using Ashbya gossypii as a model, we describe the molecular mechanism and the structural basis for the allosteric regulation of IMPDH by guanine nucleotides. We report that GTP and GDP bind to the regulatory Bateman domain, inducing octamers with compromised catalytic activity. Our data suggest that eukaryotic and prokaryotic IMPDHs might have developed different regulatory mechanisms, with GTP/GDP inhibiting only eukaryotic IMPDHs. Interestingly, mutations associated with human retinopathies map into the guanine nucleotide-binding sites including a previously undescribed non-canonical site and disrupt allosteric inhibition. Together, our results shed light on the mechanisms of the allosteric regulation of enzymes mediated by Bateman domains and provide a molecular basis for certain retinopathies, opening the door to new therapeutic approaches.

  17. Selective Negative Allosteric Modulation Of Metabotropic Glutamate Receptors - A Structural Perspective of Ligands and Mutants

    DEFF Research Database (Denmark)

    Harpsøe, Kasper; Isberg, Vignir; Tehan, Benjamin G;

    2015-01-01

    The metabotropic glutamate receptors have a wide range of modulatory functions in the central nervous system. They are among the most highly pursued drug targets, with relevance for several neurological diseases, and a number of allosteric modulators have entered clinical trials. However, so far...... this has not led to a marketed drug, largely because of the difficulties in achieving subtype-selective compounds with desired properties. Very recently the first crystal structures were published for the transmembrane domain of two metabotropic glutamate receptors in complex with negative allosteric...... modulators. In this analysis, we make the first comprehensive structural comparison of all metabotropic glutamate receptors, placing selective negative allosteric modulators and critical mutants into the detailed context of the receptor binding sites. A better understanding of how the different m...

  18. Hemoglobin and the origins of the concept of allosterism.

    Science.gov (United States)

    Edsall, J T

    1980-02-01

    heterotropic interactions. Brief final comments relate to the evolution of the concept of reversible conformational transitions as the basis for both homotropic and heterotropic interactions in allosteric proteins. PMID:6986293

  19. COMMUNICATIVE COMPETENCE

    Directory of Open Access Journals (Sweden)

    Józef Podgórecki

    2015-01-01

    Full Text Available The paper presents the most significant factors that influence interpersonal and group communication in multicultural environment in education. It highlights main theories of intercultural communication and its effectiveness as well as ones which deal with coping with conflicts in the intercultural environment. In contemporary times, which require working in multicultural environment, communicative skills become more and more important. In teachers’ work cultural awareness and being openminded about differences between nations and cultures are essential. These skills are especially important while there is a need to avoid or overcome problems, conflicts which may occur. The author shows the significance of these factors. The article closes with the recommendations and clues concerning effective intercultural communication.

  20. Optimization of a Dibenzodiazepine Hit to a Potent and Selective Allosteric PAK1 Inhibitor.

    Science.gov (United States)

    Karpov, Alexei S; Amiri, Payman; Bellamacina, Cornelia; Bellance, Marie-Helene; Breitenstein, Werner; Daniel, Dylan; Denay, Regis; Fabbro, Doriano; Fernandez, Cesar; Galuba, Inga; Guerro-Lagasse, Stephanie; Gutmann, Sascha; Hinh, Linda; Jahnke, Wolfgang; Klopp, Julia; Lai, Albert; Lindvall, Mika K; Ma, Sylvia; Möbitz, Henrik; Pecchi, Sabina; Rummel, Gabriele; Shoemaker, Kevin; Trappe, Joerg; Voliva, Charles; Cowan-Jacob, Sandra W; Marzinzik, Andreas L

    2015-07-01

    The discovery of inhibitors targeting novel allosteric kinase sites is very challenging. Such compounds, however, once identified could offer exquisite levels of selectivity across the kinome. Herein we report our structure-based optimization strategy of a dibenzodiazepine hit 1, discovered in a fragment-based screen, yielding highly potent and selective inhibitors of PAK1 such as 2 and 3. Compound 2 was cocrystallized with PAK1 to confirm binding to an allosteric site and to reveal novel key interactions. Compound 3 modulated PAK1 at the cellular level and due to its selectivity enabled valuable research to interrogate biological functions of the PAK1 kinase. PMID:26191365

  1. Shift in the Equilibrium between On and Off States of the Allosteric Switch in Ras-GppNHp Affected by Small Molecules and Bulk Solvent Composition

    Energy Technology Data Exchange (ETDEWEB)

    Holzapfel, Genevieve; Buhrman, Greg; Mattos, Carla (NCSU)

    2012-08-31

    Ras GTPase cycles between its active GTP-bound form promoted by GEFs and its inactive GDP-bound form promoted by GAPs to affect the control of various cellular functions. It is becoming increasingly apparent that subtle regulation of the GTP-bound active state may occur through promotion of substates mediated by an allosteric switch mechanism that induces a disorder to order transition in switch II upon ligand binding at an allosteric site. We show with high-resolution structures that calcium acetate and either dithioerythritol (DTE) or dithiothreitol (DTT) soaked into H-Ras-GppNHp crystals in the presence of a moderate amount of poly(ethylene glycol) (PEG) can selectively shift the equilibrium to the 'on' state, where the active site appears to be poised for catalysis (calcium acetate), or to what we call the 'ordered off' state, which is associated with an anticatalytic conformation (DTE or DTT). We also show that the equilibrium is reversible in our crystals and dependent on the nature of the small molecule present. Calcium acetate binding in the allosteric site stabilizes the conformation observed in the H-Ras-GppNHp/NOR1A complex, and PEG, DTE, and DTT stabilize the anticatalytic conformation observed in the complex between the Ras homologue Ran and Importin-{beta}. The small molecules are therefore selecting biologically relevant conformations in the crystal that are sampled by the disordered switch II in the uncomplexed GTP-bound form of H-Ras. In the presence of a large amount of PEG, the ordered off conformation predominates, whereas in solution, in the absence of PEG, switch regions appear to remain disordered in what we call the off state, unable to bind DTE.

  2. Myasis occuring in a neonate

    Directory of Open Access Journals (Sweden)

    Temitope O. Obasa

    2012-12-01

    Full Text Available Myasis is the infestation of skin by larvae or maggots of a variety of flies. It is a condition that occurs more commonly in adults who are living and/or have visited tropical countries. It rarely occurs in neonates, and even when seen, only few larvae are extracted. This case report describes myasis occurring in an 11-day-old female who had 47 larvae in her skin.

  3. Elastic network model of allosteric regulation in protein kinase PDK1

    Directory of Open Access Journals (Sweden)

    Williams Gareth

    2010-05-01

    Full Text Available Abstract Background Structural switches upon binding of phosphorylated moieties underpin many signalling networks. The ligand activation is a form of allosteric modulation of the protein, where the binding site is remote from the structural change in the protein. Recently this structural switch has been elegantly demonstrated with the crystallisation of the activated form of 3-phosphoinositide-dependent protein kinase-1 (PDK1. The purpose of the present work is to determine whether the allosteric coupling in PDK1 emerges at the level of a simple coarse grained model of protein dynamics. Results It is shown here that the allosteric effects of the agonist binding to the small lobe upon the activation loop in the large lobe of PDK1 are explainable within a simple 'ball and spring' elastic network model (ENM of protein dynamics. In particular, the model shows that the bound phospho peptide mimetic fluctuations have a high degree of correlation with the activation loop of PDK1. Conclusions The ENM approach to small molecule activation of proteins may offer a first pass predictive methodology where affinity is encoded in residues remote from the active site, and aid in the design of specific protein agonists that enhance the allosteric coupling and antagonist that repress it.

  4. Mutations in Antibody Fragments Modulate Allosteric Response Via Hydrogen-Bond Network Fluctuations.

    Science.gov (United States)

    Srivastava, Amit; Tracka, Malgorzata B; Uddin, Shahid; Casas-Finet, Jose; Livesay, Dennis R; Jacobs, Donald J

    2016-05-10

    A mechanical perturbation method that locally restricts conformational entropy along the protein backbone is used to identify putative allosteric sites in a series of antibody fragments. The method is based on a distance constraint model that integrates mechanical and thermodynamic viewpoints of protein structure wherein mechanical clamps that mimic substrate or cosolute binding are introduced. Across a set of six single chain-Fv fragments of the anti-lymphotoxin-β receptor antibody, statistically significant responses are obtained by averaging over 10 representative structures sampled from a molecular dynamics simulation. As expected, the introduced clamps locally rigidify the protein, but long-ranged increases in both rigidity and flexibility are also frequently observed. Expanding our analysis to every molecular dynamics frame demonstrates that the allosteric responses are modulated by fluctuations within the hydrogen-bond network where the native ensemble is comprised of conformations that both are, and are not, affected by the perturbation in question. Population shifts induced by the mutations alter the allosteric response by adjusting which hydrogen-bond networks are the most probable. These effects are compared using response maps that track changes across each single chain-Fv fragment, thus providing valuable insight into how sensitive allosteric mechanisms are to mutations. PMID:27166802

  5. Coevolutionary analysis enabled rational deregulation of allosteric enzyme inhibition in Corynebacterium glutamicum for lysine production.

    Science.gov (United States)

    Chen, Zhen; Meyer, Weiqian; Rappert, Sugima; Sun, Jibin; Zeng, An-Ping

    2011-07-01

    Product feedback inhibition of allosteric enzymes is an essential issue for the development of highly efficient microbial strains for bioproduction. Here we used aspartokinase from Corynebacterium glutamicum (CgAK), a key enzyme controlling the biosynthesis of industrially important aspartate family amino acids, as a model to demonstrate a fast and efficient approach to the deregulation of allostery. In the last 50 years many researchers and companies have made considerable efforts to deregulate this enzyme from allosteric inhibition by lysine and threonine. However, only a limited number of positive mutants have been identified so far, almost exclusively by random mutation and selection. In this study, we used statistical coupling analysis of protein sequences, a method based on coevolutionary analysis, to systematically clarify the interaction network within the regulatory domain of CgAK that is essential for allosteric inhibition. A cluster of interconnected residues linking different inhibitors' binding sites as well as other regions of the protein have been identified, including most of the previously reported positions of successful mutations. Beyond these mutation positions, we have created another 14 mutants that can partially or completely desensitize CgAK from allosteric inhibition, as shown by enzyme activity assays. The introduction of only one of the inhibition-insensitive CgAK mutations (here Q298G) into a wild-type C. glutamicum strain by homologous recombination resulted in an accumulation of 58 g/liter L-lysine within 30 h of fed-batch fermentation in a bioreactor. PMID:21531824

  6. Rational design of allosteric regulation of homoserine dehydrogenase by a nonnatural inhibitor L-lysine.

    Science.gov (United States)

    Chen, Zhen; Rappert, Sugima; Zeng, An-Ping

    2015-02-20

    Allosteric proteins, which can sense different signals, are interesting biological parts for synthetic biology. In particular, the design of an artificial allosteric enzyme to sense an unnatural signal is both challenging and highly desired, for example, for a precise and dynamical control of fluxes of growth-essential but byproduct pathways in metabolic engineering of industrial microorganisms. In this work, we used homoserine dehydrogenase (HSDH) of Corynebacterium glutamicum, which is naturally allosterically regulated by threonine and isoleucine, as an example to demonstrate the feasibility of reengineering an allosteric enzyme to respond to an unnatural inhibitor L-lysine. For this purpose, the natural threonine binding sites of HSD were first predicted and verified by mutagenesis experiments. The threonine binding sites were then engineered to a lysine binding pocket. The reengineered HSD only responds to lysine inhibition but not to threonine. This is a significant step toward the construction of artificial molecular circuits for dynamic control of growth-essential byproduct formation pathway for lysine biosynthesis. PMID:24344690

  7. Allosteric ligands for the pharmacologically dark receptors GPR68 and GPR65.

    Science.gov (United States)

    Huang, Xi-Ping; Karpiak, Joel; Kroeze, Wesley K; Zhu, Hu; Chen, Xin; Moy, Sheryl S; Saddoris, Kara A; Nikolova, Viktoriya D; Farrell, Martilias S; Wang, Sheng; Mangano, Thomas J; Deshpande, Deepak A; Jiang, Alice; Penn, Raymond B; Jin, Jian; Koller, Beverly H; Kenakin, Terry; Shoichet, Brian K; Roth, Bryan L

    2015-11-26

    At least 120 non-olfactory G-protein-coupled receptors in the human genome are 'orphans' for which endogenous ligands are unknown, and many have no selective ligands, hindering the determination of their biological functions and clinical relevance. Among these is GPR68, a proton receptor that lacks small molecule modulators for probing its biology. Using yeast-based screens against GPR68, here we identify the benzodiazepine drug lorazepam as a non-selective GPR68 positive allosteric modulator. More than 3,000 GPR68 homology models were refined to recognize lorazepam in a putative allosteric site. Docking 3.1 million molecules predicted new GPR68 modulators, many of which were confirmed in functional assays. One potent GPR68 modulator, ogerin, suppressed recall in fear conditioning in wild-type but not in GPR68-knockout mice. The same approach led to the discovery of allosteric agonists and negative allosteric modulators for GPR65. Combining physical and structure-based screening may be broadly useful for ligand discovery for understudied and orphan GPCRs. PMID:26550826

  8. Allosteric transition and binding of small molecule effectors causes curvature change in central β-sheets of selected enzymes.

    Science.gov (United States)

    Tolonen, Ellen; Bueno, Brenda; Kulshreshta, Sanjeev; Cieplak, Piotr; Argáez, Miguel; Velázquez, Leticia; Stec, Boguslaw

    2011-04-01

    A quantitative description of allosteric transition remains a significant science challenge. Many allosteric enzymes contain a central β-sheet in their catalytic domain. When an allosteric protein undergoes the transition between T (tense) and R (relaxed) allosteric states, this central β-sheet undergoes a conformational change. A traditional method of measuring this change, the root mean square deviation (RMSD), appears to be inadequate to describe such changes in meaningful quantitative manner. We designed a novel quantitative method to demonstrate this conformational transition by measuring the change in curvature of the central β-sheet when enzymes transition between allosteric states. The curvature was established by calculating the semiaxes of a 3-D hyperboloid fitted by least squares to the Cα atomic positions of the β-sheet. The two enzymes selected for this study, fructose 1,6-bisphosphatase (FBPase) from pig kidney and aspartate carbamoyltransferase (ATCase) from E. coli, showed while transitioning between the allosteric states (T ⇔ R) a notable change in β-sheet curvature (∼5%) that results in a large lateral shift at the sheet's edge, which is necessary to convey the signal. The results suggest that the β-sheet participates in storing elastic energy associated with the transition. Establishing a tentative link between the energetics of the β-sheet in different allosteric states provides a more objective basis for the naming convention of allosteric states (tense or relaxed), and provides insight into the hysteretic nature of the transition. The approach presented here allows for a better understanding of the internal dynamics of allosteric enzymes by defining the domains that directly participate in the transition. PMID:20602244

  9. What political developments may occur?

    International Nuclear Information System (INIS)

    Energy is going to play a major role in politics in the next two decades. This is due to four basic facts. In the first place, energy is a vital element in economic development, international trade and communications. Secondly secure energy is one of the elementary requirements of any credible defense and security strategy. Thirdly, the degradation of the global environment is directly linked with energy production, consumption and waste. Finally, the energy market and related markets such as the transport and communications sectors depend on a huge net of coordinated infrastructure. Basic changes in the energy sector require considerable time and massive investments. Energy solutions thus depend on long-term strategies. (author)

  10. Allosteric vs. spontaneous exit-site (E-site) tRNA dissociation early in protein synthesis.

    Science.gov (United States)

    Chen, Chunlai; Stevens, Benjamin; Kaur, Jaskiran; Smilansky, Zeev; Cooperman, Barry S; Goldman, Yale E

    2011-10-11

    During protein synthesis, deacylated transfer RNAs leave the ribosome via an exit (E) site after mRNA translocation. How the ribosome regulates tRNA dissociation and whether functional linkages between the aminoacyl (A) and E sites modulate the dynamics of protein synthesis have long been debated. Using single molecule fluorescence resonance energy transfer experiments, we find that, during early cycles of protein elongation, tRNAs are often held in the E site until being allosterically released when the next aminoacyl tRNA binds to the A site. This process is regulated by the length and sequence of the nascent peptide and by the conformational state, detected by tRNA proximity, prior to translocation. In later cycles, E-site tRNA dissociates spontaneously. Our results suggest that the distribution of pretranslocation tRNA states and posttranslocation pathways are correlated within each elongation cycle via communication between distant subdomains in the ribosome, but that this correlation between elongation cycle intermediates does not persist into succeeding cycles. PMID:21969541

  11. Oxidation mechanisms occurring in wines

    OpenAIRE

    Oliveira, Carla Maria; Ferreira, António César Silva; de Freitas, Victor; Artur M. S. Silva

    2011-01-01

    The present review aims to show the state of the art on the oxidation mechanisms occurring in wines, as well as the methods to monitor, classify and diagnose wine oxidation. Wine oxidation can be divided in enzymatic oxidation and non-enzymatic oxidation. Enzymatic oxidation almost entirely occurs in grape must and is largely correlated with the content of hydroxycinnamates, such as caffeoyltartaric acid and paracoumaroyltartaric acid, and flavan-3-ols. Non-enzymatic oxidation, al...

  12. CRISIS COMMUNICATION IN UNIVERSITIES

    OpenAIRE

    MADRAN, Canan; PENPECE, Dilek

    2015-01-01

    Abstract Institutions should implement effective crisis communication strategies to manage their reputations in crisis situations. Thus, the negative perceptions that may occur because of crisis can be reduced and eliminated by continuously informing stakeholders. Therefore, various researches are needed in the area of crisis communication management. The aim of the study is to determine the types of crises that often occur in universities and evaluate the crisis communication efforts in high...

  13. Probing the Sophisticated Synergistic Allosteric Regulation of Aromatic Amino Acid Biosynthesis in Mycobacterium tuberculosis Using ᴅ-Amino Acids

    Science.gov (United States)

    Reichau, Sebastian; Blackmore, Nicola J.; Jiao, Wanting; Parker, Emily J.

    2016-01-01

    Chirality plays a major role in recognition and interaction of biologically important molecules. The enzyme 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase (DAH7PS) is the first enzyme of the shikimate pathway, which is responsible for the synthesis of aromatic amino acids in bacteria and plants, and a potential target for the development of antibiotics and herbicides. DAH7PS from Mycobacterium tuberculosis (MtuDAH7PS) displays an unprecedented complexity of allosteric regulation, with three interdependent allosteric binding sites and a ternary allosteric response to combinations of the aromatic amino acids l-Trp, l-Phe and l-Tyr. In order to further investigate the intricacies of this system and identify key residues in the allosteric network of MtuDAH7PS, we studied the interaction of MtuDAH7PS with aromatic amino acids that bear the non-natural d-configuration, and showed that the d-amino acids do not elicit an allosteric response. We investigated the binding mode of d-amino acids using X-ray crystallography, site directed mutagenesis and isothermal titration calorimetry. Key differences in the binding mode were identified: in the Phe site, a hydrogen bond between the amino group of the allosteric ligands to the side chain of Asn175 is not established due to the inverted configuration of the ligands. In the Trp site, d-Trp forms no interaction with the main chain carbonyl group of Thr240 and less favourable interactions with Asn237 when compared to the l-Trp binding mode. Investigation of the MtuDAH7PSN175A variant further supports the hypothesis that the lack of key interactions in the binding mode of the aromatic d-amino acids are responsible for the absence of an allosteric response, which gives further insight into which residues of MtuDAH7PS play a key role in the transduction of the allosteric signal. PMID:27128682

  14. Naturally Occurring Radioactive Materials (NORM)

    Energy Technology Data Exchange (ETDEWEB)

    Gray, P. [ed.

    1997-02-01

    This paper discusses the broad problems presented by Naturally Occuring Radioactive Materials (NORM). Technologically Enhanced naturally occuring radioactive material includes any radionuclides whose physical, chemical, radiological properties or radionuclide concentration have been altered from their natural state. With regard to NORM in particular, radioactive contamination is radioactive material in an undesired location. This is a concern in a range of industries: petroleum; uranium mining; phosphorus and phosphates; fertilizers; fossil fuels; forestry products; water treatment; metal mining and processing; geothermal energy. The author discusses in more detail the problem in the petroleum industry, including the isotopes of concern, the hazards they present, the contamination which they cause, ways to dispose of contaminated materials, and regulatory issues. He points out there are three key programs to reduce legal exposure and problems due to these contaminants: waste minimization; NORM assesment (surveys); NORM compliance (training).

  15. Structural Determinants Defining the Allosteric Inhibition of an Essential Antibiotic Target.

    Science.gov (United States)

    Soares da Costa, Tatiana P; Desbois, Sebastien; Dogovski, Con; Gorman, Michael A; Ketaren, Natalia E; Paxman, Jason J; Siddiqui, Tanzeela; Zammit, Leanne M; Abbott, Belinda M; Robins-Browne, Roy M; Parker, Michael W; Jameson, Geoffrey B; Hall, Nathan E; Panjikar, Santosh; Perugini, Matthew A

    2016-08-01

    Dihydrodipicolinate synthase (DHDPS) catalyzes the first committed step in the lysine biosynthesis pathway of bacteria. The pathway can be regulated by feedback inhibition of DHDPS through the allosteric binding of the end product, lysine. The current dogma states that DHDPS from Gram-negative bacteria are inhibited by lysine but orthologs from Gram-positive species are not. The 1.65-Å resolution structure of the Gram-negative Legionella pneumophila DHDPS and the 1.88-Å resolution structure of the Gram-positive Streptococcus pneumoniae DHDPS bound to lysine, together with comprehensive functional analyses, show that this dogma is incorrect. We subsequently employed our crystallographic data with bioinformatics, mutagenesis, enzyme kinetics, and microscale thermophoresis to reveal that lysine-mediated inhibition is not defined by Gram staining, but by the presence of a His or Glu at position 56 (Escherichia coli numbering). This study has unveiled the molecular determinants defining lysine-mediated allosteric inhibition of bacterial DHDPS. PMID:27427481

  16. Common Internal Allosteric Network Links Anesthetic Binding Sites in a Pentameric Ligand-Gated Ion Channel.

    Science.gov (United States)

    Joseph, Thomas T; Mincer, Joshua S

    2016-01-01

    General anesthetics bind reversibly to ion channels, modifying their global conformational distributions, but the underlying atomic mechanisms are not completely known. We examine this issue by way of the model protein Gloeobacter violaceous ligand-gated ion channel (GLIC) using computational molecular dynamics, with a coarse-grained model to enhance sampling. We find that in flooding simulations, both propofol and a generic particle localize to the crystallographic transmembrane anesthetic binding region, and that propofol also localizes to an extracellular region shared with the crystallographic ketamine binding site. Subsequent simulations to probe these binding modes in greater detail demonstrate that ligand binding induces structural asymmetry in GLIC. Consequently, we employ residue interaction correlation analysis to describe the internal allosteric network underlying the coupling of ligand and distant effector sites necessary for conformational change. Overall, the results suggest that the same allosteric network may underlie the actions of various anesthetics, regardless of binding site. PMID:27403526

  17. Targeted Chemical Wedges Reveal the Role of Allosteric DNA Modulation in Protein — DNA Assembly

    OpenAIRE

    Moretti, Rocco; Donato, Leslie J.; Brezinski, Mary L.; Stafford, Ryan L.; Hoff, Helena; Thorson, Jon S.; Dervan, Peter B.; Ansari, Aseem Z.

    2008-01-01

    The cooperative assembly of multiprotein complexes results from allosteric modulations of DNA structure as well as direct intermolecular contacts between proteins. Such cooperative binding plays a critical role in imparting exquisite sequence specificity on the homeobox transcription factor (Hox) family of developmental transcription factors. A well-characterized example includes the interaction of Hox proteins with extradenticle (Exd), a highly conserved DNA binding transcription factor. Alt...

  18. FR258900, a potential anti-hyperglycemic drug, binds at the allosteric site of glycogen phosphorylase

    OpenAIRE

    Tiraidis, C.; Alexacou, K. M.; Zographos, Spyros E.; Leonidas, Demetres D.; Gimisis, T.; Oikonomakos, Nikos G.

    2007-01-01

    FR258900 has been discovered as a novel inhibitor of human liver glycogen phosphorylase a and proved to suppress hepatic glycogen breakdown and reduce plasma glucose concentrations in diabetic mice models. To elucidate the mechanism of inhibition, we have determined the crystal structure of the cocrystallized rabbit muscle glycogen phosphorylase b–FR258900 complex and refined it to 2.2 Å resolution. The structure demonstrates that the inhibitor binds at the allosteric activator site, where th...

  19. Coevolutionary Analysis Enabled Rational Deregulation of Allosteric Enzyme Inhibition in Corynebacterium glutamicum for Lysine Production ▿

    OpenAIRE

    Chen, Zhen; Meyer, Weiqian; Rappert, Sugima; Sun, Jibin; Zeng, An-Ping

    2011-01-01

    Product feedback inhibition of allosteric enzymes is an essential issue for the development of highly efficient microbial strains for bioproduction. Here we used aspartokinase from Corynebacterium glutamicum (CgAK), a key enzyme controlling the biosynthesis of industrially important aspartate family amino acids, as a model to demonstrate a fast and efficient approach to the deregulation of allostery. In the last 50 years many researchers and companies have made considerable efforts to deregul...

  20. Characterization of an allosteric citalopram-binding site at the serotonin transporter

    DEFF Research Database (Denmark)

    Chen, Fenghua; Breum Larsen, Mads; Neubauer, Henrik Amtoft;

    2005-01-01

    -citalopram, sertraline,       serotonin and paroxetine. EC50 values for S- and R-citalopram are 3.6 +/-       0.4 microm and 19.4 +/- 2.3 microm, respectively. Fluoxetine, venlafaxine       and duloxetine have no significant effect on the dissociation of       [3H]S-citalopram. Allosteric modulation of dissociation is...

  1. TOWARD UNDERSTANDING ALLOSTERIC SIGNALING MECHANISMS IN THE ATPASE DOMAIN OF MOLECULAR CHAPERONES

    OpenAIRE

    Liu, Ying; Bahar, Ivet

    2010-01-01

    The ATPase cycle of the heat shock protein 70 (HSP70) is largely dependent on the ability of its nucleotide binding domain (NBD), also called ATPase domain, to undergo structural changes between its open and closed conformations. We present here a combined study of the Hsp70 NBD sequence, structure and dynamic features to identify the residues that play a crucial role in mediating the allosteric signaling properties of the ATPase domain. Specifically, we identify the residues involved in the ...

  2. Allosteric Regulation of Histidine Kinases by Their Cognate Response Regulator Determines Cell Fate

    OpenAIRE

    Paul, Ralf; Jaeger, Tina; Abel, Sören; Wiederkehr, Irene; Folcher, Marc; Biondi, Emanuele G.; Laub, Michael T.; Jenal, Urs

    2008-01-01

    The two-component phosphorylation network is of critical importance for bacterial growth and physiology. Here, we address plasticity and interconnection of distinct signal transduction pathways within this network. In Caulobacter crescentus antagonistic activities of the PleC phosphatase and DivJ kinase localized at opposite cell poles control the phosphorylation state and subcellular localization of the cell fate determinator protein DivK. We show that DivK functions as an allosteric regulat...

  3. Early occurring and continuing effects

    International Nuclear Information System (INIS)

    This chapter deals with health-risk estimates for early and continuing effects of exposure to ionizing radiations that could be associated with light water nuclear power plants accidents. Early and continuing effects considered are nonneoplastic diseases and symptoms that normally occur soon after radiation exposure, but may also occur after years have passed. They are generally associated with relatively high (greater than 1 Gy) doses. For most of the effects considered, there is a practical dose threshold. Organs of primary interest, because of their high sensitivity or the likelihood of receiving a large radiation dose, are bone marrow, gastrointestinal tract, thyroid glands, lungs, skin, gonads, and eyes. In utero exposure of the fetus is also considered. New data and modeling techniques available since publication of the Reactor Safety Study (WASH 1400, 1975) were used along with data cited in the Study to develop improved health-risk models for morbidity and mortality. The new models are applicable to a broader range of accident scenarios, provide a more detailed treatment of dose protraction effects, and include morbidity effects not considered in the Reactor Safety Study. 115 references, 20 figures, 19 tables

  4. Naturally-occurring alpha activity

    International Nuclear Information System (INIS)

    In view of the difficulties of assessing the significance of man-made radioactivity it is important to study for comparison the background of natural radioactivity against which the human race has evolved and lives. It is also important to define the present levels of activity so that it will be possible to detect and study as quickly as possible any changes which may occur owing to the release into the environment of new radioactive materials. Moreover, by the study of the behaviour of natural radioactivity light may be shed upon that of the artificially produced isotopes and a number of analogies traced between the two groups. These concepts have led to studies of naturally-occurring radioactive materials alongside a programme of research into fission products in food, water and air, as well as studies of the metabolism of both sets of materials in the human body. Since the last report there has been a useful increase in our knowledge of natural radioactivity in the biosphere, and its levels relative to the new man-made activities. These studies have necessitated technical developments, particularly in the methods of measuring and identifying alpha-ray emitters, to which group many of the more important natural radioactive materials belong

  5. FR258900, a potential anti-hyperglycemic drug, binds at the allosteric site of glycogen phosphorylase.

    Science.gov (United States)

    Tiraidis, Costas; Alexacou, Kyra-Melinda; Zographos, Spyros E; Leonidas, Demetres D; Gimisis, Thanasis; Oikonomakos, Nikos G

    2007-08-01

    FR258900 has been discovered as a novel inhibitor of human liver glycogen phosphorylase a and proved to suppress hepatic glycogen breakdown and reduce plasma glucose concentrations in diabetic mice models. To elucidate the mechanism of inhibition, we have determined the crystal structure of the cocrystallized rabbit muscle glycogen phosphorylase b-FR258900 complex and refined it to 2.2 A resolution. The structure demonstrates that the inhibitor binds at the allosteric activator site, where the physiological activator AMP binds. The contacts from FR258900 to glycogen phosphorylase are dominated by nonpolar van der Waals interactions with Gln71, Gln72, Phe196, and Val45' (from the symmetry-related subunit), and also by ionic interactions from the carboxylate groups to the three arginine residues (Arg242, Arg309, and Arg310) that form the allosteric phosphate-recognition subsite. The binding of FR258900 to the protein promotes conformational changes that stabilize an inactive T-state quaternary conformation of the enzyme. The ligand-binding mode is different from those of the potent phenoxy-phthalate and acyl urea inhibitors, previously described, illustrating the broad specificity of the allosteric site. PMID:17600143

  6. Peptide- and proton-driven allosteric clamps catalyze anthrax toxin translocation across membranes.

    Science.gov (United States)

    Das, Debasis; Krantz, Bryan A

    2016-08-23

    Anthrax toxin is an intracellularly acting toxin in which sufficient information is available regarding the structure of its transmembrane channel, allowing for detailed investigation of models of translocation. Anthrax toxin, comprising three proteins-protective antigen (PA), lethal factor (LF), and edema factor-translocates large proteins across membranes. Here we show that the PA translocase channel has a transport function in which its catalytic active sites operate allosterically. We find that the phenylalanine clamp (ϕ-clamp), the known conductance bottleneck in the PA translocase, gates as either a more closed state or a more dilated state. Thermodynamically, the two channel states have >300-fold different binding affinities for an LF-derived peptide. The change in clamp thermodynamics requires distant α-clamp and ϕ-clamp sites. Clamp allostery and translocation are more optimal for LF peptides with uniform stereochemistry, where the least allosteric and least efficiently translocated peptide had a mixed stereochemistry. Overall, the kinetic results are in less agreement with an extended-chain Brownian ratchet model but, instead, are more consistent with an allosteric helix-compression model that is dependent also on substrate peptide coil-to-helix/helix-to-coil cooperativity. PMID:27506790

  7. What occurred in the reactors

    International Nuclear Information System (INIS)

    Described is what occurred in the reactors of Fukushima Daiichi Nuclear Power Plant at the Tohoku earthquake and tsunami (Mar. 11, 2011) from the aspect of engineering science. The tsunami attacked the Plant 1 hr after the quake. The Plant had reactors in buildings no.1-4 at 10 m height from the normal sea level which was flooded by 1.5-5.5 m high wave. All reactors in no.1-6 in the Plant were the boiling water type, and their core nuclear reactions were stopped within 3 sec due to the first quake by control rods inserted automatically. Reactors in no.1-5 lost their external AC power sources by the breakdown and subsequent submergence (no.1-4) of various equipments and in no.1, 2 and 4, the secondary DC power was then lost by the battery death. Although the isolation condenser started to cool the reactor in no.1 after DC cut, its valve was then kept closed to heat up the reactor, leading to the reaction of heated Zr in the fuel tube and water to yield H2 which was accumulated in the building: the cause of hydrogen explosion on 12th. The reactor in no.2 had the reactor core isolation cooling system (RCIC) which operated normally for few hrs, then probably stopped to heat up the reactor, resulting in meltdown of the core but no explosion occurred because of the opened door of the blowout panel on the wall by the blast of no.1 explosion. The reactor in no.3 had RCIC and high pressure coolant injection system, but their works stopped to result in the core damage and H2 accumulation leading to the explosion on 14th. The reactor in no.4 had not been operated because of its periodical annual examination, but was explored on 15th, of which cause was thought to be due to backward flow of H2 from no.3. Finally, the author discusses about this accident from the industrial aspect of the design of safety level (defense in depth) on international views, and problems and tasks given. (T.T.)

  8. Earl occurring and continuing effects

    International Nuclear Information System (INIS)

    This chapter develops health-risk models for early and continuing effects of exposure to beta or gamma radiation that could be associated with light water nuclear power plant accidents. The main purpose of the chapter is to provide details on each health-risk model and on the data used. Early and continuing effects considered are prodromal symptoms and nonneoplastic diseases that usually occur soon after a brief radiation exposure. These effects are generally associated with relatively high (greater than 1 Gy) absorbed organ doses. For most of the effects considered, there is an absorbed organ dose threshold below which no effects are seen. Some information is provided on health effects observed in victims of the Chernobyl power plant accident. Organs of primary interest, because of their high sensitivity or their potential for receiving large doses, are bone marrow, gastrointestinal tract, thyroid glands, lungs, skin, gonads, and eyes. Exposure of the fetus is also considered. Additional data and modeling techniques available since publication of the Reactor Safety Study were used to obtain models for morbidity and mortality

  9. mGlu2 Receptor Agonism, but Not Positive Allosteric Modulation, Elicits Rapid Tolerance towards Their Primary Efficacy on Sleep Measures in Rats.

    Directory of Open Access Journals (Sweden)

    Abdallah Ahnaou

    promoted homeostatic recovery sleep. From the translational perspective, the present rodent findings suggest that mGluR2 positive allosteric modulation has therapeutic potential based on its superior long term efficacy over agonists in psychiatric disorders, particularly of those commonly occurring with REM sleep overdrive.

  10. Investigation of allosteric modulation mechanism of metabotropic glutamate receptor 1 by molecular dynamics simulations, free energy and weak interaction analysis

    Science.gov (United States)

    Bai, Qifeng; Yao, Xiaojun

    2016-02-01

    Metabotropic glutamate receptor 1 (mGlu1), which belongs to class C G protein-coupled receptors (GPCRs), can be coupled with G protein to transfer extracellular signal by dimerization and allosteric regulation. Unraveling the dimer packing and allosteric mechanism can be of great help for understanding specific regulatory mechanism and designing more potential negative allosteric modulator (NAM). Here, we report molecular dynamics simulation studies of the modulation mechanism of FITM on the wild type, T815M and Y805A mutants of mGlu1 through weak interaction analysis and free energy calculation. The weak interaction analysis demonstrates that van der Waals (vdW) and hydrogen bonding play an important role on the dimer packing between six cholesterol molecules and mGlu1 as well as the interaction between allosteric sites T815, Y805 and FITM in wild type, T815M and Y805A mutants of mGlu1. Besides, the results of free energy calculations indicate that secondary binding pocket is mainly formed by the residues Thr748, Cys746, Lys811 and Ser735 except for FITM-bound pocket in crystal structure. Our results can not only reveal the dimer packing and allosteric regulation mechanism, but also can supply useful information for the design of potential NAM of mGlu1.

  11. Promoting Intercultural Communication

    Science.gov (United States)

    Muhammad, Rukiya

    2005-01-01

    Misunderstandings and breakdowns in communication often occur when we interact with people from different cultures. Therefore, it is essential for us to be sensitive to other cultures. This article analyses the prevailing problems in intercultural communication and gives suggestions to higher education institutions in the hope of improving…

  12. 12 CFR 533.3 - CRA communications.

    Science.gov (United States)

    2010-01-01

    ...-RELATED AGREEMENTS § 533.3 CRA communications. (a) Definition of CRA communication. A CRA communication is... with a Federal banking agency. An oral or written communication with a Federal banking agency is not a CRA communication if it occurred more than 3 years before the parties entered into the agreement....

  13. A negative allosteric modulator modulates GABAB-receptor signalling through GB2 subunits.

    Science.gov (United States)

    Sun, Bing; Chen, Linhai; Liu, Lei; Xia, Zhixiong; Pin, Jean-Philippe; Nan, Fajun; Liu, Jianfeng

    2016-03-15

    An γ-aminobutyric acid type B (GABAB)-receptor mediates slow and prolonged synaptic inhibition in the central nervous system, which represents an interesting target for the treatment of various diseases and disorders of the central nervous system. To date, only one activator of the GABAB-receptor, baclofen, is on the market for the treatment of spasticity. Inhibitors of the GABAB-receptor, such as antagonists, show anti-absence seizure activity and pro-cognitive properties. In a search for allosteric compounds of the GABAB-receptor, although several positive allosteric modulators have been developed, it is only recently that the first negative allosteric modulator (NAM), CLH304a (also named Compound 14), has been reported. In the present study, we provide further information on the mechanism of action of CLH304a, and also show the possibility of designing more NAMs, such as CLH391 and CLH393, based on the structure of CLH304a. First we show that CLH304a inhibits native GABAB-receptor activity in cultured cerebellar granular neurons. We then show that CLH304a has inverse agonist properties and non-competitively inhibits the effect of agonists, indicating that it binds at a different site to GABA. The GABAB-receptor is a mandatory heterodimer made of GB1 subunits, in which agonists bind, and GB2 subunits, which activate G-proteins. By using various combinations made up of wild-type and/or mutated GB1 and GB2 subunits, we show that CLH304a acts on the heptahelical domain of GB2 subunits. These data revealed the possibility of designing innovative NAMs acting in the heptahelical domain of the GB2 subunits, offering novel possibilities for therapeutic intervention based on GABAB-receptor inhibition. PMID:26772870

  14. Targeting the Akt1 allosteric site to identify novel scaffolds through virtual screening.

    Science.gov (United States)

    Yilmaz, Oya Gursoy; Olmez, Elif Ozkirimli; Ulgen, Kutlu O

    2014-02-01

    Preclinical data and tumor specimen studies report that AKT kinases are related to many human cancers. Therefore, identification and development of small molecule inhibitors targeting AKT and its signaling pathway can be therapeutic in treatment of cancer. Numerous studies report inhibitors that target the ATP-binding pocket in the kinase domains, but the similarity of this site, within the kinase family makes selectivity a major problem. The sequence identity amongst PH domains is significantly lower than that in kinase domains and developing more selective inhibitors is possible if PH domain is targeted. This in silico screening study is the first time report toward the identification of potential allosteric inhibitors expected to bind the cavity between kinase and PH domains of Akt1. Structural information of Akt1 was used to develop structure-based pharmacophore models comprising hydrophobic, acceptor, donor and ring features. The 3D structural information of previously identified allosteric Akt inhibitors obtained from literature was employed to develop a ligand-based pharmacophore model. Database was generated with drug like subset of ZINC and screening was performed based on 3D similarity to the selected pharmacophore hypotheses. Binding modes and affinities of the ligands were predicted by Glide software. Top scoring hits were further analyzed considering 2D similarity between the compounds, interactions with Akt1, fitness to pharmacophore models, ADME, druglikeness criteria and Induced-Fit docking. Using virtual screening methodologies, derivatives of 3-methyl-xanthine, quinoline-4-carboxamide and 2-[4-(cyclohexa-1,3-dien-1-yl)-1H-pyrazol-3-yl]phenol were proposed as potential leads for allosteric inhibition of Akt1. PMID:24291487

  15. Ultrasensitivity and heavy-metal selectivity of the allosterically modulated MerR transcription complex.

    OpenAIRE

    Ralston, D M; O'Halloran, T V

    1990-01-01

    The MerR metalloregulatory protein is a heavy-metal receptor that functions as the repressor and Hg(II)-responsive transcription activator of the prokaryotic mercury-resistance (mer) genes. We demonstrate that this allosterically modulated regulatory protein is sensitive to HgCl2 concentrations of 1.0 +/- 0.3 x 10(-8) M in the presence of 1.0 x 10(-3) M dithiothreitol for half-maximal induction of transcription of the mer promoter by Escherichia coli RNA polymerase in vitro. Transcription med...

  16. Ibuprofen impairs allosterically peroxynitrite isomerization by ferric human serum heme-albumin.

    OpenAIRE

    Ascenzi, Paolo; di Masi, Alessandra; Coletta, Massimo; Ciaccio, Chiara; Fanali, Gabriella; Nicoletti, Francesco P; Smulevich, Giulietta; Fasano, Mauro

    2011-01-01

    Human serum albumin (HSA) participates in heme scavenging; in turn, heme endows HSA with myoglobin-like reactivity and spectroscopic properties. Here, the allosteric effect of ibuprofen on peroxynitrite isomerization to NO3− catalyzed by ferric human serum heme-albumin (HSA-heme-Fe(III)) is reported. Data were obtained at 22.0 °C. HSA-heme-Fe(III) catalyzes peroxynitrite isomerization in the absence and presence of CO2; the values of the second order catalytic rate constant (kon) are 4.1 × 10...

  17. Complex pharmacology of novel allosteric free fatty acid 3 receptor ligands

    DEFF Research Database (Denmark)

    Hudson, Brian D; Christiansen, Elisabeth; Murdoch, Hannah; Jenkins, Laura; Hansen, Anders Højgaard; Madsen, Ole; Ulven, Trond; Milligan, Graeme

    2014-01-01

    this series resulted in compounds completely lacking activity, acting as FFA3 PAMs, or appearing to act as FFA3-negative allosteric modulators. However, the pharmacology of this series was further complicated in that certain analogs displaying overall antagonism of FFA3 function actually appeared to...... chemical series, considerable care must be taken to define the pharmacological characteristics of specific compounds before useful predictions of their activity and their use in defining specific roles of FFA3 in either in vitro and in vivo settings can be made....

  18. A Potential Yeast Actin Allosteric Conduit Dependent on Hydrophobic Core Residues Val-76 and Trp-79*

    OpenAIRE

    Wen, Kuo-Kuang; McKane, Melissa; Stokasimov, Ema; Fields, Jonathon; Rubenstein, Peter A.

    2010-01-01

    Intramolecular allosteric interactions responsible for actin conformational regulation are largely unknown. Previous work demonstrated that replacing yeast actin Val-76 with muscle actin Ile caused decreased nucleotide exchange. Residue 76 abuts Trp-79 in a six-residue linear array beginning with Lys-118 on the surface and ending with His-73 in the nucleotide cleft. To test if altering the degree of packing of these two residues would affect actin dynamics, we constructed V76I, W79F, and W79Y...

  19. Dynamical Allosterism in the Mechanism of Action of DNA Mismatch Repair Protein MutS

    OpenAIRE

    Pieniazek, Susan N.; Hingorani, Manju M.; Beveridge, D.L.

    2011-01-01

    The multidomain protein Thermus aquaticus MutS and its prokaryotic and eukaryotic homologs recognize DNA replication errors and initiate mismatch repair. MutS actions are fueled by ATP binding and hydrolysis, which modulate its interactions with DNA and other proteins in the mismatch-repair pathway. The DNA binding and ATPase activities are allosterically coupled over a distance of ∼70 Å, and the molecular mechanism of coupling has not been clarified. To address this problem, all-atom molecul...

  20. Substituted 3-Benzylcoumarins as Allosteric MEK1 Inhibitors: Design, Synthesis and Biological Evaluation as Antiviral Agents

    Directory of Open Access Journals (Sweden)

    Ping Xu

    2013-05-01

    Full Text Available In order to find novel antiviral agents, a series of allosteric MEK1 inhibitors were designed and synthesized. Based on docking results, multiple optimizations were made on the coumarin scaffold. Some of the derivatives showed excellent MEK1 binding affinity in the appropriate enzymatic assays and displayed obvious inhibitory effects on the ERK pathway in a cellular assay. These compounds also significantly inhibited virus (EV71 replication in HEK293 and RD cells. Several compounds showed potential as agents for the treatment of viral infective diseases, with the most potent compound 18 showing an IC50 value of 54.57 nM in the MEK1 binding assay.

  1. Chemogenomic discovery of allosteric antagonists at the GPRC6A receptor

    DEFF Research Database (Denmark)

    Gloriam, David E.; Wellendorph, Petrine; Johansen, Lars Dan; Thomsen, Alex Rojas Bie; Phonekeo, Karina; Pedersen, Daniel Sejer; Bräuner-Osborne, Hans

    2011-01-01

    pharmacological character: (1) chemogenomic lead identification through the first, to our knowledge, ligand inference between two different GPCR families, Families A and C; and (2) the discovery of the most selective GPRC6A allosteric antagonists discovered to date. The unprecedented inference of...... pharmacological activity across GPCR families provides proof-of-concept for in silico approaches against Family C targets based on Family A templates, greatly expanding the prospects of successful drug design and discovery. The antagonists were tested against a panel of seven Family A and C G protein-coupled receptors...

  2. Steric hindrance mutagenesis in the conserved extracellular vestibule impedes allosteric binding of antidepressants to the serotonin transporter

    DEFF Research Database (Denmark)

    Plenge, Per; Shi, Lei; Beuming, Thijs;

    2012-01-01

    The serotonin transporter (SERT) controls synaptic serotonin levels and is the primary target for antidepressants, including selective serotonin reuptake inhibitors (e.g. (S)-citalopram) and tricyclic antidepressants (e.g. clomipramine). In addition to a high affinity binding site, SERT possesses a...... involved in the allosteric binding in the extracellular vestibule located above the central substrate binding (S1) site. Indeed, mutagenesis of selected residues in the vestibule reduces the allosteric potency of (S)-citalopram and clomipramine. The identified site is further supported by the inhibitory...

  3. A Monoclonal Antibody (MCPR3-7) Interfering with the Activity of Proteinase 3 by an Allosteric Mechanism*

    Science.gov (United States)

    Hinkofer, Lisa C.; Seidel, Susanne A. I.; Korkmaz, Brice; Silva, Francisco; Hummel, Amber M.; Braun, Dieter; Jenne, Dieter E.; Specks, Ulrich

    2013-01-01

    Proteinase 3 (PR3) is an abundant serine protease of neutrophil granules and a major target of autoantibodies (PR3 anti-neutrophil cytoplasmic antibodies) in granulomatosis with polyangiitis. Some of the PR3 synthesized by promyelocytes in the bone marrow escapes the targeting to granules and occurs on the plasma membrane of naive and primed neutrophils. This membrane-associated PR3 antigen may represent pro-PR3, mature PR3, or both forms. To discriminate between mature PR3 and its inactive zymogen, which have different conformations, we generated and identified a monoclonal antibody called MCPR3-7. It bound much better to pro-PR3 than to mature PR3. This monoclonal antibody greatly reduced the catalytic activity of mature PR3 toward extended peptide substrates. Using diverse techniques and multiple recombinant PR3 variants, we characterized its binding properties and found that MCPR3-7 preferentially bound to the so-called activation domain of the zymogen and changed the conformation of mature PR3, resulting in impaired catalysis and inactivation by α1-proteinase inhibitor (α1-antitrypsin). Noncovalent as well as covalent complexation between PR3 and α1-proteinase inhibitor was delayed in the presence of MCPR3-7, but cleavage of certain thioester and paranitroanilide substrates with small residues in the P1 position was not inhibited. We conclude that MCPR3-7 reduces PR3 activity by an allosteric mechanism affecting the S1′ pocket and further prime side interactions with substrates. In addition, MCPR3-7 prevents binding of PR3 to cellular membranes. Inhibitory antibodies targeting the activation domain of PR3 could be exploited as highly selective inhibitors of PR3, scavengers, and clearers of the PR3 autoantigen in granulomatosis with polyangiitis. PMID:23902773

  4. ThermoTRP channels as modular proteins with allosteric gating.

    Science.gov (United States)

    Latorre, Ramon; Brauchi, Sebastian; Orta, Gerardo; Zaelzer, Cristián; Vargas, Guillermo

    2007-01-01

    Ion channels activate by sensing stimuli such as membrane voltage, ligand binding or temperature and transduce this information into conformational changes that open the channel pore. Thus, a key question in understanding ion channel function is how do the protein domains involved in sensing stimuli (sensors) and opening the pore (gates) communicate. In this regard, transient receptor potential (TRP) channels that confer thermosensation [A. Dhaka, V. Viswanath, A. Patapoutian, TRP ion channels and temperature sensation, Annu. Rev. Neurosci. 29 (2006) 135-161; I.S. Ramsey, M. Delling, D.E. Clapham, An introduction to TRP channels, Annu. Rev. Physiol. 68 (2006) 619-647] (thermoTRP; Q(10)>10) are unique to the extent that they integrate a variety of physical and chemical stimuli. In some cases such as, for example, the vanilloid receptor TRPV1 [M.J. Caterina, M.A. Schumacher, M. Tominaga, T.A. Rosen, J.D. Levine, D. Julius, The capsaicin receptor: a heat-activated ion channel in the pain pathway, Nature 389 (1997) 816-824] and TRPA1 [G.M. Story, A.M. Peier, A.J. Reeve, S.R. Eid, J. Mosbacher, T.R. Hricik, T.J. Earley, A.C. Hergarden, D.A. Andersson, S.W. Hwang, P. McIntyre, T. Jegla, S. Bevan, A. Patapoutian, ANKTM1, a TRP-like channel expressed in nociceptive neurons, is activated by cold temperatures, Cell 112 (2003) 819-829; S. Jordt, D. Julius, Molecular basis for species-specific sensitivity to "hot" chilli peppers, Cell 108 (2002) 421-430] the integration of these stimuli elicit pain [M. Tominaga, M.J. Caterina, A.B. Malmberg, T.A. Rosen, H. Gilbert, K. Skinner, B.E. Raumann, A.I. Basbaum, D. Julius, The cloned capsaicin receptor integrates multiple pain-producing stimuli, Neuron 21 (1998) 531-543; M. Bandell, A. Dubin, M. Petrus, A. Orth, J. Mathur, S. Hwang, A. Patapoutian, High-throughput random mutagenesis screen reveals TRPM8 residues specifically required for activation by menthol, Nat. Neurosci. 9 (2006) 466-468; S. Zurborg, B. Yurgionas, JA. Jira, O

  5. Selective binding modes and allosteric inhibitory effects of lupane triterpenes on protein tyrosine phosphatase 1B.

    Science.gov (United States)

    Jin, Tiantian; Yu, Haibo; Huang, Xu-Feng

    2016-01-01

    Protein Tyrosine Phosphatase 1B (PTP1B) has been recognized as a promising therapeutic target for treating obesity, diabetes, and certain cancers for over a decade. Previous drug design has focused on inhibitors targeting the active site of PTP1B. However, this has not been successful because the active site is positively charged and conserved among the protein tyrosine phosphatases. Therefore, it is important to develop PTP1B inhibitors with alternative inhibitory strategies. Using computational studies including molecular docking, molecular dynamics simulations, and binding free energy calculations, we found that lupane triterpenes selectively inhibited PTP1B by targeting its more hydrophobic and less conserved allosteric site. These findings were verified using two enzymatic assays. Furthermore, the cell culture studies showed that lupeol and betulinic acid inhibited the PTP1B activity stimulated by TNFα in neurons. Our study indicates that lupane triterpenes are selective PTP1B allosteric inhibitors with significant potential for treating those diseases with elevated PTP1B activity. PMID:26865097

  6. Biomimetic Design Results in a Potent Allosteric Inhibitor of Dihydrodipicolinate Synthase from Campylobacter jejuni.

    Science.gov (United States)

    Skovpen, Yulia V; Conly, Cuylar J T; Sanders, David A R; Palmer, David R J

    2016-02-17

    Dihydrodipicolinate synthase (DHDPS), an enzyme required for bacterial peptidoglycan biosynthesis, catalyzes the condensation of pyruvate and β-aspartate semialdehyde (ASA) to form a cyclic product which dehydrates to form dihydrodipicolinate. DHDPS has, for several years, been considered a putative target for novel antibiotics. We have designed the first potent inhibitor of this enzyme by mimicking its natural allosteric regulation by lysine, and obtained a crystal structure of the protein-inhibitor complex at 2.2 Å resolution. This novel inhibitor, which we named "bislysine", resembles two lysine molecules linked by an ethylene bridge between the α-carbon atoms. Bislysine is a mixed partial inhibitor with respect to the first substrate, pyruvate, and a noncompetitive partial inhibitor with respect to ASA, and binds to all forms of the enzyme with a Ki near 200 nM, more than 300 times more tightly than lysine. Hill plots show that the inhibition is cooperative, indicating that the allosteric sites are not independent despite being located on opposite sides of the protein tetramer, separated by approximately 50 Å. A mutant enzyme resistant to lysine inhibition, Y110F, is strongly inhibited by this novel inhibitor, suggesting this may be a promising strategy for antibiotic development. PMID:26836694

  7. Engineering and optimization of an allosteric biosensor protein for peroxisome proliferator-activated receptor γ ligands.

    Science.gov (United States)

    Li, Jingjing; Gierach, Izabela; Gillies, Alison R; Warden, Charles D; Wood, David W

    2011-11-15

    The peroxisome proliferator-activated receptor gamma (PPARγ or PPARG) belongs to the nuclear receptor superfamily, and is a potential drug target for a variety of diseases. In this work, we constructed a series of bacterial biosensors for the identification of functional PPARγ ligands. These sensors entail modified Escherichia coli cells carrying a four-domain fusion protein, comprised of the PPARγ ligand binding domain (LBD), an engineered mini-intein domain, the E. coli maltose binding protein (MBD), and a thymidylate synthase (TS) reporter enzyme. E. coli cells expressing this protein exhibit hormone ligand-dependent growth phenotypes. Unlike our published estrogen (ER) and thyroid receptor (TR) biosensors, the canonical PPARγ biosensor cells displayed pronounced growth in the absence of ligand. They were able to distinguish agonists and antagonists, however, even in the absence of agonist. To improve ligand sensitivity of this sensor, we attempted to engineer and optimize linker peptides flanking the PPARγ LBD insertion point. Truncation of the original linkers led to decreased basal growth and significantly enhanced ligand sensitivity of the PPARγ sensor, while substitution of the native linkers with optimized G(4)S (Gly-Gly-Gly-Gly-Ser) linkers further increased the sensitivity. Our studies demonstrate that the properties of linkers, especially the C-terminal linker, greatly influence the efficiency and fidelity of the allosteric signal induced by ligand binding. Our work also suggests an approach to increase allosteric behavior in this multidomain sensor protein, without modification of the functional LBD. PMID:21893405

  8. Allosteric effects of chromophore interaction with dimeric near-infrared fluorescent proteins engineered from bacterial phytochromes.

    Science.gov (United States)

    Stepanenko, Olesya V; Baloban, Mikhail; Bublikov, Grigory S; Shcherbakova, Daria M; Stepanenko, Olga V; Turoverov, Konstantin K; Kuznetsova, Irina M; Verkhusha, Vladislav V

    2016-01-01

    Fluorescent proteins (FPs) engineered from bacterial phytochromes attract attention as probes for in vivo imaging due to their near-infrared (NIR) spectra and use of available in mammalian cells biliverdin (BV) as chromophore. We studied spectral properties of the iRFP670, iRFP682 and iRFP713 proteins and their mutants having Cys residues able to bind BV either in both PAS (Cys15) and GAF (Cys256) domains, in one of these domains, or without these Cys residues. We show that the absorption and fluorescence spectra and the chromophore binding depend on the location of the Cys residues. Compared with NIR FPs in which BV covalently binds to Cys15 or those that incorporate BV noncovalently, the proteins with BV covalently bound to Cys256 have blue-shifted spectra and higher quantum yield. In dimeric NIR FPs without Cys15, the covalent binding of BV to Сys256 in one monomer allosterically inhibits the covalent binding of BV to the other monomer, whereas the presence of Cys15 allosterically promotes BV binding to Cys256 in both monomers. The NIR FPs with both Cys residues have the narrowest blue-shifted spectra and the highest quantum yield. Our analysis resulted in the iRFP713/Val256Cys protein with the highest brightness in mammalian cells among available NIR FPs. PMID:26725513

  9. An external sodium ion binding site controls allosteric gating in TRPV1 channels.

    Science.gov (United States)

    Jara-Oseguera, Andres; Bae, Chanhyung; Swartz, Kenton J

    2016-01-01

    TRPV1 channels in sensory neurons are integrators of painful stimuli and heat, yet how they integrate diverse stimuli and sense temperature remains elusive. Here, we show that external sodium ions stabilize the TRPV1 channel in a closed state, such that removing the external ion leads to channel activation. In studying the underlying mechanism, we find that the temperature sensors in TRPV1 activate in two steps to favor opening, and that the binding of sodium to an extracellular site exerts allosteric control over temperature-sensor activation and opening of the pore. The binding of a tarantula toxin to the external pore also exerts control over temperature-sensor activation, whereas binding of vanilloids influences temperature-sensitivity by largely affecting the open/closed equilibrium. Our results reveal a fundamental role of the external pore in the allosteric control of TRPV1 channel gating and provide essential constraints for understanding how these channels can be tuned by diverse stimuli. PMID:26882503

  10. Mechanisms of allosteric gene regulation by NMR quantification of microsecond-millisecond protein dynamics.

    Science.gov (United States)

    Kleckner, Ian R; Gollnick, Paul; Foster, Mark P

    2012-01-13

    The trp RNA-binding attenuation protein (TRAP) is a paradigmatic allosteric protein that regulates the tryptophan biosynthetic genes associated with the trp operon in bacilli. The ring-shaped 11-mer TRAP is activated for recognition of a specific trp-mRNA target by binding up to 11 tryptophan molecules. To characterize the mechanisms of tryptophan-induced TRAP activation, we have performed methyl relaxation dispersion (MRD) nuclear magnetic resonance (NMR) experiments that probe the time-dependent structure of TRAP in the microsecond-to-millisecond "chemical exchange" time window. We find significant side chain flexibility localized to the RNA and tryptophan binding sites of the apo protein and that these dynamics are dramatically reduced upon ligand binding. Analysis of the MRD NMR data provides insights into the structural nature of transiently populated conformations sampled in solution by apo TRAP. The MRD data are inconsistent with global two-state exchange, indicating that conformational sampling in apo TRAP is asynchronous. These findings imply a temporally heterogeneous population of structures that are incompatible with RNA binding and substantiate the study of TRAP as a paradigm for probing and understanding essential dynamics in allosteric, regulatory proteins. PMID:22115774

  11. Structural Insights into the Allosteric Operation of the Lon AAA+ Protease.

    Science.gov (United States)

    Lin, Chien-Chu; Su, Shih-Chieh; Su, Ming-Yuan; Liang, Pi-Hui; Feng, Chia-Cheng; Wu, Shih-Hsiung; Chang, Chung-I

    2016-05-01

    The Lon AAA+ protease (LonA) is an evolutionarily conserved protease that couples the ATPase cycle into motion to drive substrate translocation and degradation. A hallmark feature shared by AAA+ proteases is the stimulation of ATPase activity by substrates. Here we report the structure of LonA bound to three ADPs, revealing the first AAA+ protease assembly where the six protomers are arranged alternately in nucleotide-free and bound states. Nucleotide binding induces large coordinated movements of conserved pore loops from two pairs of three non-adjacent protomers and shuttling of the proteolytic groove between the ATPase site and a previously unknown Arg paddle. Structural and biochemical evidence supports the roles of the substrate-bound proteolytic groove in allosteric stimulation of ATPase activity and the conserved Arg paddle in driving substrate degradation. Altogether, this work provides a molecular framework for understanding how ATP-dependent chemomechanical movements drive allosteric processes for substrate degradation in a major protein-destruction machine. PMID:27041592

  12. The Structural Basis for Allosteric Inhibition of a Threonine-sensitive Aspartokinase*

    Science.gov (United States)

    Liu, Xuying; Pavlovsky, Alexander G.; Viola, Ronald E.

    2008-01-01

    The commitment step to the aspartate pathway of amino acid biosynthesis is the phosphorylation of aspartic acid catalyzed by aspartokinase (AK). Most microorganisms and plants have multiple forms of this enzyme, and many of these isofunctional enzymes are subject to feedback regulation by the end products of the pathway. However, the archeal species Methanococcus jannaschii has only a single, monofunctional form of AK. The substrate l-aspartate binds to this recombinant enzyme in two different orientations, providing the first structural evidence supporting the relaxed regiospecificity previously observed with several alternative substrates of Escherichia coli AK (Angeles, T. S., Hunsley, J. R., and Viola, R. E. (1992) Biochemistry31 ,799 -8051731937). Binding of the nucleotide substrate triggers significant domain movements that result in a more compact quaternary structure. In contrast, the highly cooperative binding of the allosteric regulator l-threonine to multiple sites on this dimer of dimers leads to an open enzyme structure. A comparison of these structures supports a mechanism for allosteric regulation in which the domain movements induced by threonine binding causes displacement of the substrates from the enzyme, resulting in a relaxed, inactive conformation. PMID:18334478

  13. The Structural Basis for Allosteric Inhibition of a Threonine-sensitive Aspartokinase

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xuying; Pavlovsky, Alexander G.; Viola, Ronald E. (Toledo)

    2008-10-08

    The commitment step to the aspartate pathway of amino acid biosynthesis is the phosphorylation of aspartic acid catalyzed by aspartokinase (AK). Most microorganisms and plants have multiple forms of this enzyme, and many of these isofunctional enzymes are subject to feedback regulation by the end products of the pathway. However, the archeal species Methanococcus jannaschii has only a single, monofunctional form of AK. The substrate l-aspartate binds to this recombinant enzyme in two different orientations, providing the first structural evidence supporting the relaxed regiospecificity previously observed with several alternative substrates of Escherichia coli AK. Binding of the nucleotide substrate triggers significant domain movements that result in a more compact quaternary structure. In contrast, the highly cooperative binding of the allosteric regulator l-threonine to multiple sites on this dimer of dimers leads to an open enzyme structure. A comparison of these structures supports a mechanism for allosteric regulation in which the domain movements induced by threonine binding causes displacement of the substrates from the enzyme, resulting in a relaxed, inactive conformation.

  14. Empathy and Communication with Animals

    OpenAIRE

    Nihat, ÇALIŞKAN; Mehmet, AYDIN; Mustafa, ASLANDEREN

    2014-01-01

    Communication, one of the essential elements of the life, can happen sometimes with a word, sometimes with a touch or a look. That’s why, communication does not only include the conversations people make between themselves, it can occur in various types among living beings. Communication develops with interaction, mutual exchange of feelings and thoughts and sharing. Communication is also to know what to be conveyed and when, where and how it will be conveyed. There are some necessary factor...

  15. Allosteric Inactivation of a Trypsin-Like Serine Protease by An Antibody Binding to the 37- and 70-Loops

    DEFF Research Database (Denmark)

    Kromann-Hansen, Tobias; Lund, Ida K; Liu, Zhuo;

    2013-01-01

    for elucidating fundamental allosteric mechanisms. The monoclonal antibody mU1 has previously been shown to be able to inhibit the function of murine urokinase-type plasminogen activator in vivo. We have now mapped the epitope of mU1 to the catalytic domain's 37- and 70-loops, situated about 20 Å from...

  16. Positive allosteric modulation of the human metabotropic glutamate receptor 4 (hmGluR4) by SIB-1893 and MPEP

    DEFF Research Database (Denmark)

    Mathiesen, Jesper Mosolff; Svendsen, Nannette; Bräuner-Osborne, Hans;

    2003-01-01

    We have identified 2-methyl-6-(2-phenylethenyl)pyridine (SIB-1893) and 2-methyl-6-phenylethynyl pyridine hydrochloride (MPEP) as positive allosteric modulators for the hmGluR4. SIB-1893 and MPEP enhanced the potency and efficacy of L-2-amino-4-phophonobutyrate (L-AP4) in guanosine 5'-O-(3-[(35)S]...

  17. Mapping of the Allosteric Site in Cholesterol Hydroxylase CYP46A1 for Efavirenz, a Drug That Stimulates Enzyme Activity.

    Science.gov (United States)

    Anderson, Kyle W; Mast, Natalia; Hudgens, Jeffrey W; Lin, Joseph B; Turko, Illarion V; Pikuleva, Irina A

    2016-05-27

    Cytochrome P450 46A1 (CYP46A1) is a microsomal enzyme and cholesterol 24-hydroxylase that controls cholesterol elimination from the brain. This P450 is also a potential target for Alzheimer disease because it can be activated pharmacologically by some marketed drugs, as exemplified by efavirenz, the anti-HIV medication. Previously, we suggested that pharmaceuticals activate CYP46A1 allosterically through binding to a site on the cytosolic protein surface, which is different from the enzyme active site facing the membrane. Here we identified this allosteric site for efavirenz on CYP46A1 by using a combination of hydrogen-deuterium exchange coupled to MS, computational modeling, site-directed mutagenesis, and analysis of the CYP46A1 crystal structure. We also mapped the binding region for the CYP46A1 redox partner oxidoreductase and found that the allosteric and redox partner binding sites share a common border. On the basis of the data obtained, we propose the mechanism of CYP46A1 allostery and the pathway for the signal transmission from the P450 allosteric site to the active site. PMID:27056331

  18. Thermodynamics and structural analysis of positive allosteric modulation of the ionotropic glutamate receptor GluA2

    DEFF Research Database (Denmark)

    Krintel, Christian; Frydenvang, Karla; Olsen, Lars; Kristensen, Maria T; de Barrios, Oriol; Naur, Peter; Francotte, Pierre; Pirotte, Bernard; Gajhede, Michael; Kastrup, Jette Sandholm

    2012-01-01

    Positive allosteric modulators of the ionotropic glutamate receptor-2 (GluA2) are promising compounds for the treatment of cognitive disorders, e.g. Alzheimer's disease. These modulators bind within the dimer interface of the ligand-binding domain and stabilize the agonist-bound conformation slow...

  19. In silico-screening approaches for lead generation: identification of novel allosteric modulators of human-erythrocyte pyruvate kinase.

    Science.gov (United States)

    Tripathi, Ashutosh; Safo, Martin K

    2012-01-01

    Identification of allosteric binding site modulators have gained increased attention lately for their potential to be developed as selective agents with a novel chemotype and targeting perhaps a new and unique binding site with probable fewer side effects. Erythrocyte pyruvate kinase (R-PK) is an important glycolytic enzyme that can be pharmacologically modulated through its allosteric effectors for the treatment of hemolytic anemia, sickle-cell anemia, hypoxia-related diseases, and other disorders arising from erythrocyte PK malfunction. An in-silico screening approach was applied to identify novel allosteric modulators of pyruvate kinase. A small-molecules database of the National Cancer Institute (NCI), was virtually screened based on structure/ligand-based pharmacophore. The virtual screening campaign led to the identification of several compounds with similar pharmacophoric features as fructose-1,6-bisphosphate (FBP), the natural allosteric activator of the kinase. The compounds were subsequently docked into the FBP-binding site using the programs FlexX and GOLD, and their interactions with the protein were analyzed with the energy-scoring function of HINT. Seven promising candidates were obtained from the NCI and subjected to kinetics analysis, which revealed both activators and inhibitors of the R-isozyme of PK (R-PK). PMID:22052500

  20. Modulation of Ultrafast Conformational Dynamics in Allosteric Interaction of Gal Repressor Protein with Different Operator DNA Sequences.

    Science.gov (United States)

    Choudhury, Susobhan; Naiya, Gitashri; Singh, Priya; Lemmens, Peter; Roy, Siddhartha; Pal, Samir Kumar

    2016-04-01

    Although all forms of dynamical behaviour of a protein under allosteric interaction with effectors are predicted, little evidence of ultrafast dynamics in the interaction has been reported. Here, we demonstrate the efficacy of a combined approach involving picosecond-resolved FRET and polarisation-gated fluorescence for the exploration of ultrafast dynamics in the allosteric interaction of the Gal repressor (GalR) protein dimer with DNA operator sequences OE and OI . FRET from the single tryptophan residue to a covalently attached probe IAEDANS at a cysteine residue in the C-terminal domain of GalR shows structural perturbation and conformational dynamics during allosteric interaction. Polarisation-gated fluorescence spectroscopy of IAEDANS and another probe (FITC) covalently attached to the operator directly revealed the essential dynamics for cooperativity in the protein-protein interaction. The ultrafast resonance energy transfer from IAEDANS in the protein to FITC also revealed different dynamic flexibility in the allosteric interaction. An attempt was made to correlate the dynamic changes in the protein dimers with OE and OI with the consequent protein-protein interaction (tetramerisation) to form a DNA loop encompassing the promoter segment. PMID:26914958

  1. A3 Adenosine Receptor Allosteric Modulator Induces an Anti-Inflammatory Effect: In Vivo Studies and Molecular Mechanism of Action

    Directory of Open Access Journals (Sweden)

    Shira Cohen

    2014-01-01

    Full Text Available The A3 adenosine receptor (A3AR is overexpressed in inflammatory cells and in the peripheral blood mononuclear cells of individuals with inflammatory conditions. Agonists to the A3AR are known to induce specific anti-inflammatory effects upon chronic treatment. LUF6000 is an allosteric compound known to modulate the A3AR and render the endogenous ligand adenosine to bind to the receptor with higher affinity. The advantage of allosteric modulators is their capability to target specifically areas where adenosine levels are increased such as inflammatory and tumor sites, whereas normal body cells and tissues are refractory to the allosteric modulators due to low adenosine levels. LUF6000 administration induced anti-inflammatory effect in 3 experimental animal models of rat adjuvant induced arthritis, monoiodoacetate induced osteoarthritis, and concanavalin A induced liver inflammation in mice. The molecular mechanism of action points to deregulation of signaling proteins including PI3K, IKK, IκB, Jak-2, and STAT-1, resulting in decreased levels of NF-κB, known to mediate inflammatory effects. Moreover, LUF6000 induced a slight stimulatory effect on the number of normal white blood cells and neutrophils. The anti-inflammatory effect of LUF6000, mechanism of action, and the differential effects on inflammatory and normal cells position this allosteric modulator as an attractive and unique drug candidate.

  2. NMR Mapping of the IFNAR1-EC binding site on IFNα2 reveals allosteric changes in the IFNAR2-EC binding site

    Science.gov (United States)

    Akabayov, Sabine Ruth; Biron, Zohar; Lamken, Peter; Piehler, Jacob; Anglister, Jacob

    2010-01-01

    All type I interferons (IFNs) bind to a common cell-surface receptor consisting of two subunits. IFNs initiate intracellular signal transduction cascades by simultaneous interaction with the extracellular domains of its receptor subunits IFNAR1 and IFNAR2. In this study we mapped the surface of IFNα2 interacting with the extracellular domain of IFNAR1 (IFNAR1-EC) by following changes in or the disappearance of the [1H,15N]-TROSY-HSQC cross peaks of IFNα2 caused by the binding of the extracellular domain of IFNAR1 (IFNAR1-EC) to the binary complex of IFNα2 with IFNAR2-EC. The NMR study on the 89 kDa complex was conducted at pH 8 and 308 K using an 800 MHz spectrometer. IFNAR1 binding affected a total of 47 out of 165 IFNα2 residues contained in two large patches on the face of the protein opposing the binding site for IFNAR2 and in a third patch located on the face containing the IFNAR2 binding site. The first two patches form the IFNAR1 binding site and one of these matches the IFNAR1 binding site previously identified by site-directed mutagenesis. The third patch partially matches the IFNα2 binding site for IFNAR2-EC indicating allosteric communication between the binding sites for the two receptor subunits. PMID:20047337

  3. Exploring the allosteric mechanism of dihydrodipicolinate synthase by reverse engineering of the allosteric inhibitor binding sites and its application for lysine production.

    Science.gov (United States)

    Geng, Feng; Chen, Zhen; Zheng, Ping; Sun, Jibin; Zeng, An-Ping

    2013-03-01

    Dihydrodipicolinate synthase (DHDPS, EC 4.2.1.52) catalyzes the first committed reaction of L-lysine biosynthesis in bacteria and plants and is allosterically regulated by L-lysine. In previous studies, DHDPSs from different species were proved to have different sensitivity to L-lysine inhibition. In this study, we investigated the key determinants of feedback regulation between two industrially important DHDPSs, the L-lysine-sensitive DHDPS from Escherichia coli and L-lysine-insensitive DHDPS from Corynebacterium glutamicum, by sequence and structure comparisons and site-directed mutation. Feedback inhibition of E. coli DHDPS was successfully alleviated after substitution of the residues around the inhibitor's binding sites with those of C. glutamicum DHDPS. Interestingly, mutagenesis of the lysine binding sites of C. glutamicum DHDPS according to E. coli DHDPS did not recover the expected feedback inhibition but an activation of DHDPS by L-lysine, probably due to differences in the allosteic signal transduction in the DHDPS of these two organisms. Overexpression of L-lysine-insensitive E. coli DHDPS mutants in E. coli MG1655 resulted in an improvement of L-lysine production yield by 46 %. PMID:22644522

  4. Participatory Communication

    DEFF Research Database (Denmark)

    Tufte, Thomas

    This user guide on participatory communication aims to answer the following questions: What do we mean when we say participatory communication? What are the practical implications of working with participatory communication strategies in development and social change processes? What practical...... experiences document that participatory communication adds value to a development project or program? Many communication practitioners and development workers face obstacles and challenges in their practical work. A participatory communication strategy offers a very specific perspective on how to articulate......, tools, and experiences on how to implement participatory communications strategies. It is targeted toward government officials, World Bank staff, develompent workers in the field, and civil society....

  5. Communication Strategy

    OpenAIRE

    Šlapáková, Petra

    2009-01-01

    This document introduces a definition of communication strategy and its close contexts. At the beginning it presents the theme of the communication and its historical development. Consequently there are explanations of the communication process, its requirements, schemes, parts. Document shows a basic division of the communication, its functions, components, tools and describes its usage in daily life of business. The communication is introduced as a tool for social interaction as an instrume...

  6. Multimedia communication

    OpenAIRE

    Vondra, Zdeněk

    2010-01-01

    Multimedia is a form of communication and sharing knowledge using synergic effect of parallel connected communication channels. Its main use is in producing communications products and services and in design of user interfaces. Main objective of this dissertation is to develop and create a model of multimedia communication for better understanding of the meaning and the purpose of using multimedia forms in communication process. The model will describe a system of elements and parameters of m...

  7. An allosteric mechanism inferred from molecular dynamics simulations on phospholamban pentamer in lipid membranes.

    Directory of Open Access Journals (Sweden)

    Peng Lian

    Full Text Available Phospholamban functions as a regulator of Ca(2+ concentration of cardiac muscle cells by triggering the bioactivity of sarcoplasmic reticulum Ca(2+-ATPase. In order to understand its dynamic mechanism in the environment of bilayer surroundings, we performed long time-scale molecular dynamic simulations based on the high-resolution NMR structure of phospholamban pentamer. It was observed from the molecular dynamics trajectory analyses that the conformational transitions between the "bellflower" and "pinwheel" modes were detected for phospholamban. Particularly, the two modes became quite similar to each other after phospholamban was phosphorylated at Ser16. Based on these findings, an allosteric mechanism was proposed to elucidate the dynamic process of phospholamban interacting with Ca(2+-ATPase.

  8. Small Molecule-Induced Allosteric Activation of the Vibrio Cholerae RTX Cysteine Protease Domain

    Energy Technology Data Exchange (ETDEWEB)

    Lupardus, P.J.; Shen, A.; Bogyo, M.; Garcia, K.C.

    2009-05-19

    Vibrio cholerae RTX (repeats in toxin) is an actin-disrupting toxin that is autoprocessed by an internal cysteine protease domain (CPD). The RTX CPD is efficiently activated by the eukaryote-specific small molecule inositol hexakisphosphate (InsP{sub 6}), and we present the 2.1 angstrom structure of the RTX CPD in complex with InsP{sub 6}. InsP{sub 6} binds to a conserved basic cleft that is distant from the protease active site. Biochemical and kinetic analyses of CPD mutants indicate that InsP{sub 6} binding induces an allosteric switch that leads to the autoprocessing and intracellular release of toxin-effector domains.

  9. Discovery of a novel allosteric modulator of 5-HT3 receptor

    DEFF Research Database (Denmark)

    Trattnig, Sarah M; Harpsøe, Kasper; Thygesen, Sarah B; Rahr, Louise M; Ahring, Philip K; Balle, Thomas; Jensen, Anders A

    2012-01-01

    class of negative allosteric modulators of the 5HT3 receptors (5HT3Rs). PU02 (6[(1naphthylmethyl)thio]9Hpurine) is a potent and selective antagonist displaying IC50 values ~1 µM at 5-HT3Rs and substantially lower activities at other Cys-loop receptors. In an elaborate mutagenesis study of the 5HT3A...... molecular determinants of PU02 activity with minor contributions from Ser292 and Val310, and we propose that the naphthalene group of PU02 docks into the hydrophobic cavity formed by these. Interestingly, specific mutations of Ser248, Thr294 and Gly306 convert PU02 into a complex modulator, potentiating and...

  10. Allosteric inhibitors of plasma membrane Ca2+ pumps: Invention and applications of caloxins

    Institute of Scientific and Technical Information of China (English)

    Jyoti; Pande; M; Szewczyk; Ashok; K; Grover

    2011-01-01

    Plasma membrane Ca2+pumps(PMCA)play a major role in Ca2+homeostasis and signaling by extruding cellular Ca2+with high affinity.PMCA isoforms are encoded by four genes which are expressed differentially in various cell types in normal and disease states.Therefore, PMCA isoform selective inhibitors would aid in delineating their role in physiology and pathophysiology.We are testing the hypothesis that extracellular domains of PMCA can be used as allosteric targets to obtain a novel class of PMCA-specific inhibitors termed caloxins. This review presents the concepts behind the invention of caloxins and our progress in this area.A section is also devoted to the applications of caloxins in literature. We anticipate that isoform-selective caloxins will aid in understanding PMCA physiology in health and disease. With strategies to develop therapeutics from bioactive peptides,caloxins may become clinically useful in car diovascular diseases,neurological disorders,retinopathy,cancer and contraception.

  11. Structural Mechanism of Allosteric Activity Regulation in a Ribonucleotide Reductase with Double ATP Cones.

    Science.gov (United States)

    Johansson, Renzo; Jonna, Venkateswara Rao; Kumar, Rohit; Nayeri, Niloofar; Lundin, Daniel; Sjöberg, Britt-Marie; Hofer, Anders; Logan, Derek T

    2016-06-01

    Ribonucleotide reductases (RNRs) reduce ribonucleotides to deoxyribonucleotides. Their overall activity is stimulated by ATP and downregulated by dATP via a genetically mobile ATP cone domain mediating the formation of oligomeric complexes with varying quaternary structures. The crystal structure and solution X-ray scattering data of a novel dATP-induced homotetramer of the Pseudomonas aeruginosa class I RNR reveal the structural bases for its unique properties, namely one ATP cone that binds two dATP molecules and a second one that is non-functional, binding no nucleotides. Mutations in the observed tetramer interface ablate oligomerization and dATP-induced inhibition but not the ability to bind dATP. Sequence analysis shows that the novel type of ATP cone may be widespread in RNRs. The present study supports a scenario in which diverse mechanisms for allosteric activity regulation are gained and lost through acquisition and evolutionary erosion of different types of ATP cone. PMID:27133024

  12. Allosteric Inhibitors of the NS3 Protease from the Hepatitis C Virus

    Science.gov (United States)

    Abian, Olga; Vega, Sonia; Sancho, Javier; Velazquez-Campoy, Adrian

    2013-01-01

    The nonstructural protein 3 (NS3) from the hepatitis C virus processes the non-structural region of the viral precursor polyprotein in infected hepatic cells. The NS3 protease activity has been considered a target for drug development since its identification two decades ago. Although specific inhibitors have been approved for clinical therapy very recently, resistance-associated mutations have already been reported for those drugs, compromising their long-term efficacy. Therefore, there is an urgent need for new anti-HCV agents with low susceptibility to resistance-associated mutations. Regarding NS3 protease, two strategies have been followed: competitive inhibitors blocking the active site and allosteric inhibitors blocking the binding of the accessory viral protein NS4A. In this work we exploit the intrinsic Zn+2-regulated plasticity of the protease to identify a new type of allosteric inhibitors. In the absence of Zn+2, the NS3 protease adopts a partially-folded inactive conformation. We found ligands binding to the Zn+2-free NS3 protease, trap the inactive protein, and block the viral life cycle. The efficacy of these compounds has been confirmed in replicon cell assays. Importantly, direct calorimetric assays reveal a low impact of known resistance-associated mutations, and enzymatic assays provide a direct evidence of their inhibitory activity. They constitute new low molecular-weight scaffolds for further optimization and provide several advantages: 1) new inhibition mechanism simultaneously blocking substrate and cofactor interactions in a non-competitive fashion, appropriate for combination therapy; 2) low impact of known resistance-associated mutations; 3) inhibition of NS4A binding, thus blocking its several effects on NS3 protease. PMID:23936097

  13. Positive allosteric modulators to peptide GPCRs:a promising class of drugs

    Institute of Scientific and Technical Information of China (English)

    Tamas BARTFAI; Ming-wei WANG

    2013-01-01

    The task of finding selective and stable peptide receptor agonists with low molecular weight,desirable pharmacokinetic properties and penetrable to the blood-brain barrier has proven too difficult for many highly coveted drug targets,including receptors for endothelin,vasoactive intestinal peptide and galanin.These receptors and ligand-gated ion channels activated by structurally simple agonists such as glutamate,glycine and GABA present such a narrow chemical space that the design of subtype-selective molecules capable of distinguishing a dozen of glutamate and GABA receptor subtypes and possessing desirable pharmacokinetic properties has also been problematic.In contrast,the pharmaceutical industry demonstrates a remarkable success in developing 1,4-benzodiazepines,positive allosteric modulators (PMAs) of the GABAA receptor.They were synthesized over 50 years ago and discovered to have anxiolytic potential through an in vivo assay.As exemplified by Librium,Valium and Dormicum,these allosteric ligands of the receptor became the world's first blockbuster drugs.Through molecular manipulation over the past 2 decades,including mutations and knockouts of the endogenous ligands or their receptors,and by in-depth physiological and pharmacological studies,more peptide and glutamate receptors have become well-validated drug targets for which an agonist is sought.In such cases,the pursuit for PAMs has also intensified,and a working paradigm to identify drug candidates that are designed as PAMs has emerged.This review,which focuses on the general principles of finding PAMs of peptide receptors in the 21st century,describes the workflow and some of its resulting compounds such as PAMs of galanin receptor 2 that act as potent anticonvulsant agents.

  14. Assessment of direct gating and allosteric modulatory effects of meprobamate in recombinant GABA(A) receptors.

    Science.gov (United States)

    Kumar, Manish; Dillon, Glenn H

    2016-03-15

    Meprobamate is a schedule IV anxiolytic and the primary metabolite of the muscle relaxant carisoprodol. Meprobamate modulates GABAA (γ-aminobutyric acid Type A) receptors, and has barbiturate-like activity. To gain insight into its actions, we have conducted a series of studies using recombinant GABAA receptors. In αxβzγ2 GABAA receptors (where x=1-6 and z=1-3), the ability to enhance GABA-mediated current was evident for all α subunit isoforms, with the largest effect observed in α5-expressing receptors. Direct gating was present with all α subunits, although attenuated in α3-expressing receptors. Allosteric and direct effects were comparable in α1β1γ2 and α1β2γ2 receptors, whereas allosteric effects were enhanced in α1β2 compared to α1β2γ2 receptors. In "extrasynaptic" (α1β3δ and α4β3δ) receptors, meprobamate enhanced EC20 and saturating GABA currents, and directly activated these receptors. The barbiturate antagonist bemegride attenuated direct effects of meprobamate. Whereas pentobarbital directly gated homomeric β3 receptors, meprobamate did not, and instead blocked the spontaneously open current present in these receptors. In wild type homomeric ρ1 receptors, pentobarbital and meprobamate were ineffective in direct gating; a mutation known to confer sensitivity to pentobarbital did not confer sensitivity to meprobamate. Our results provide insight into the actions of meprobamate and parent therapeutic agents such as carisoprodol. Whereas in general actions of meprobamate were comparable to those of carisoprodol, differential effects of meprobamate at some receptor subtypes suggest potential advantages of meprobamate may be exploited. A re-assessment of previously synthesized meprobamate-related carbamate molecules for myorelaxant and other therapeutic indications is warranted. PMID:26872987

  15. Novel positive allosteric modulators of the human α7 nicotinic acetylcholine receptor.

    Science.gov (United States)

    Arias, Hugo R; Gu, Ruo-Xu; Feuerbach, Dominik; Guo, Bao-Bao; Ye, Yong; Wei, Dong-Qing

    2011-06-14

    The pharmacological activity of a series of novel amide derivatives was characterized on several nicotinic acetylcholine receptors (AChRs). Ca(2+) influx results indicate that these compounds are not agonists of the human (h) α4β2, α3β4, α7, and α1β1γδ AChRs; compounds 2-4 are specific positive allosteric modulators (PAMs) of hα7 AChRs, whereas compounds 1-4, 7, and 12 are noncompetitive antagonists of the other AChRs. Radioligand binding results indicate that PAMs do not inhibit binding of [(3)H]methyllycaconitine but enhance binding of [(3)H]epibatidine to hα7 AChRs, indicating that these compounds do not directly, but allosterically, interact with the hα7 agonist sites. Additional competition binding results indicate that the antagonistic action mediated by these compounds is produced by direct interaction with neither the phencyclidine site in the Torpedo AChR ion channel nor the imipramine and the agonist sites in the hα4β2 and hα3β4 AChRs. Molecular dynamics and docking results suggest that the binding site for compounds 2-4 is mainly located in the inner β-sheet of the hα7-α7 interface, ∼12 Å from the agonist locus. Hydrogen bond interactions between the amide group of the PAMs and the hα7 AChR binding site are found to be critical for their activity. The dual PAM and antagonistic activities elicited by compounds 2-4 might be therapeutically important. PMID:21510634

  16. Dual-cavity basket promotes encapsulation in water in an allosteric fashion.

    Science.gov (United States)

    Chen, Shigui; Yamasaki, Makoto; Polen, Shane; Gallucci, Judith; Hadad, Christopher M; Badjić, Jovica D

    2015-09-30

    We prepared dual-cavity basket 1 to carry six (S)-alanine residues at the entrance of its two juxtaposed cavities (289 Å(3)). With the assistance of (1)H NMR spectroscopy and calorimetry, we found that 1 could trap a single molecule of 4 (K1 = 1.45 ± 0.40 × 10(4) M(-1), ITC), akin in size (241 Å(3)) and polar characteristics to nerve agent VX (289 Å(3)). The results of density functional theory calculations (DFT, M06-2X/6-31G*) and experiments ((1)H NMR spectroscopy) suggest that the negative homotropic allosterism arises from the guest forming C-H···π contacts with all three of the aromatic walls of the occupied basket's cavity. In response, the other cavity increases its size and turns rigid to prevent the formation of the ternary complex. A smaller guest 6 (180 Å(3)), akin in size and polar characteristics to soman (186 Å(3)), was also found to bind to dual-cavity 1, although giving both binary [1⊂6] and ternary [1⊂62] complexes (K1 = 7910 M(-1) and K2 = 2374 M(-1), (1)H NMR spectroscopy). In this case, the computational and experimental ((1)H NMR spectroscopy) results suggest that only two aromatic walls of the occupied basket's cavity form C-H···π contacts with the guest to render the singly occupied host flexible enough to undergo additional structural changes necessary for receiving another guest molecule. The structural adaptivity of dual-cavity baskets of type 1 is unique and important for designing multivalent hosts capable of effectively sequestering targeted guests in an allosteric manner to give stable supramolecular polymers. PMID:26348904

  17. Risk communication

    International Nuclear Information System (INIS)

    This paper deals with risk communication, understood as the exchange of knowledge and opinions between various actors involved in risk management. Because of new risks created by man's scientific and technological ingenuity, risk communication attains ever wider social functions, involving an increasing number of people. The tasks for risk communication often reflect conflicting perspectives and interests of the communicating parties. The author stresses the importance of communication quality, i.e. its adequacy, understandability and credibility. Risk communication has to cope with problems such as the discrepancy between the perspectives of laymen and experts, uncertainties in risk assessment and the lack of scientific literacy among the public. One of the major conditions for successful risk communication is trust in the communicators, balanced with some skepticism and critical mind. The author finally suggests that, instead of promoting ''understanding of technology'', risk communication should foster and understanding of the necessary compatibility of technology, societal and environmental issues. (author)

  18. CSR communication

    DEFF Research Database (Denmark)

    Golob, Ursa; Podnar, Klement; Elving, Wim;

    2013-01-01

    Purpose – This paper aims to introduce the special issue on CSR communication attached to the First International CSR Communication Conference held in Amsterdam in October 2011. The aim of the introduction is also to review CSR communication papers published in scholarly journals in order to make...... a summary of the state of CSR communication knowledge. Design/methodology/approach – The existing literature on CSR communication was approached via systematic review. with a combination of conventional and summative qualitative content analysis. The final dataset contained 90 papers from two main business...... communications. The most important outlets for CSR communication-related topics are Journal of Business Ethics and Corporate Communications: An International Journal. Originality/value – This paper represents the first attempt to perform a systematic and comprehensive overview of CSR communication papers...

  19. Single Enzyme Studies Reveal the Existence of Discrete Functional States for Monomeric Enzymes and How They Are “Selected” upon Allosteric Regulation

    DEFF Research Database (Denmark)

    Hatzakis, Nikos S.; Wei, Li; Jørgensen, Sune Klamer;

    2012-01-01

    Allosteric regulation of enzymatic activity forms the basis for controlling a plethora of vital cellular processes. While the mechanism underlying regulation of multimeric enzymes is generally well understood and proposed to primarily operate via conformational selection, the mechanism underlying...... allosteric regulation of monomeric enzymes is poorly understood. Here we monitored for the first time allosteric regulation of enzymatic activity at the single molecule level. We measured single stochastic catalytic turnovers of a monomeric metabolic enzyme (Thermomyces lanuginosus Lipase) while titrating...... its proximity to a lipid membrane that acts as an allosteric effector. The single molecule measurements revealed the existence of discrete binary functional states that could not be identified in macroscopic measurements due to ensemble averaging. The discrete functional states correlate with the...

  20. Communication systems

    International Nuclear Information System (INIS)

    This paper gives a survey of the field of data communication. The topics covered are: Types of communication, protocols, communication control systems, communication equipment and techniques, and types of data nets. Further, some of the data nets in use today, and the techniques applied in their implementation, are described. The intent of the paper is not to give an in-depth analysis of the various data communication techniques; rather, to describe the principles and problems involved in the construction of a state-of-the-art communication system. (Auth.)

  1. On the G-Protein-Coupled Receptor Heteromers and Their Allosteric Receptor-Receptor Interactions in the Central Nervous System: Focus on Their Role in Pain Modulation

    OpenAIRE

    Kjell Fuxe; Tarakanov, Alexander O.; Luigi F. Agnati; Alicia Rivera; Kathleen Van Craenenbroeck; Wilber Romero-Fernandez; Dasiel O. Borroto-Escuela

    2013-01-01

    The modulatory role of allosteric receptor-receptor interactions in the pain pathways of the Central Nervous System and the peripheral nociceptors has become of increasing interest. As integrators of nociceptive and antinociceptive wiring and volume transmission signals, with a major role for the opioid receptor heteromers, they likely have an important role in the pain circuits and may be involved in acupuncture. The delta opioid receptor (DOR) exerts an antagonistic allosteric influence on ...

  2. Insights into Protein – DNA Interactions, Stability and Allosteric Communications: A Computational Study of Mutsα-DNA Recognition Complexes

    OpenAIRE

    Negureanu, Lacramioara; Salsbury, Freddie R.

    2012-01-01

    DNA mismatch repair proteins (MMR) maintain genetic stability by recognizing and repairing mismatched bases and insertion/deletion loops mistakenly incorporated during DNA replication, and initiate cellular response to certain types of DNA damage. Loss of MMR in mammalian cells has been linked to resistance to certain DNA damaging chemotherapeutic agents, as well as to increase risk of cancer. Mismatch repair pathway is considered to involve the concerted action of at least 20 proteins. The m...

  3. Role of Arginine 293 and Glutamine 288 in Communication between Catalytic and Allosteric Sites in Yeast Ribonucleotide Reductase

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Md. Faiz; Kaushal, Prem Singh; Wan, Qun; Wijerathna, Sanath R.; An, Xiuxiang; Huang, Mingxia; Dealwis, Chris Godfrey (Case Western); (Colorado)

    2012-11-01

    Ribonucleotide reductases (RRs) catalyze the rate-limiting step of de novo deoxynucleotide (dNTP) synthesis. Eukaryotic RRs consist of two proteins, RR1 ({alpha}) that contains the catalytic site and RR2 ({beta}) that houses a diferric-tyrosyl radical essential for ribonucleoside diphosphate reduction. Biochemical analysis has been combined with isothermal titration calorimetry (ITC), X-ray crystallography and yeast genetics to elucidate the roles of two loop 2 mutations R293A and Q288A in Saccharomyces cerevisiae RR1 (ScRR1). These mutations, R293A and Q288A, cause lethality and severe S phase defects, respectively, in cells that use ScRR1 as the sole source of RR1 activity. Compared to the wild-type enzyme activity, R293A and Q288A mutants show 4% and 15%, respectively, for ADP reduction, whereas they are 20% and 23%, respectively, for CDP reduction. ITC data showed that R293A ScRR1 is unable to bind ADP and binds CDP with 2-fold lower affinity compared to wild-type ScRR1. With the Q288A ScRR1 mutant, there is a 6-fold loss of affinity for ADP binding and a 2-fold loss of affinity for CDP compared to the wild type. X-ray structures of R293A ScRR1 complexed with dGTP and AMPPNP-CDP [AMPPNP, adenosine 5-({beta},{gamma}-imido)triphosphate tetralithium salt] reveal that ADP is not bound at the catalytic site, and CDP binds farther from the catalytic site compared to wild type. Our in vivo functional analyses demonstrated that R293A cannot support mitotic growth, whereas Q288A can, albeit with a severe S phase defect. Taken together, our structure, activity, ITC and in vivo data reveal that the arginine 293 and glutamine 288 residues of ScRR1 are crucial in facilitating ADP and CDP substrate selection.

  4. Naturally occurring pentacyclic triterpenes as inhibitors of glycogen phosphorylase: synthesis, structure-activity relationships, and X-ray crystallographic studies.

    Science.gov (United States)

    Wen, Xiaoan; Sun, Hongbin; Liu, Jun; Cheng, Keguang; Zhang, Pu; Zhang, Liying; Hao, Jia; Zhang, Luyong; Ni, Peizhou; Zographos, Spyros E; Leonidas, Demetres D; Alexacou, Kyra-Melinda; Gimisis, Thanasis; Hayes, Joseph M; Oikonomakos, Nikos G

    2008-06-26

    Twenty-five naturally occurring pentacyclic triterpenes, 15 of which were synthesized in this study, were biologically evaluated as inhibitors of rabbit muscle glycogen phosphorylase a (GPa). From SAR studies, the presence of a sugar moiety in triterpene saponins resulted in a markedly decreased activity ( 7, 18- 20) or no activity ( 21, 22). These saponins, however, might find their value as potential natural prodrugs which are much more water-soluble than their corresponding aglycones. To elucidate the mechanism of GP inhibition, we have determined the crystal structures of the GPb-asiatic acid and GPb-maslinic acid complexes. The X-ray analysis indicates that the inhibitors bind at the allosteric activator site, where the physiological activator AMP binds. Pentacyclic triterpenes represent a promising class of multiple-target antidiabetic agents that exert hypoglycemic effects, at least in part, through GP inhibition. PMID:18517260

  5. Data communications

    Energy Technology Data Exchange (ETDEWEB)

    Preckshot, G.G. [Lawrence Livermore National Lab., CA (United States)

    1993-08-01

    The purpose of this paper is to recommend regulatory guidance for reviewers examining computer communication systems used in nuclear power plants. The recommendations cover three areas important to these communications systems: system design, communication protocols, and communication media. The first area, system design, considers three aspects of system design--questions about architecture, specific risky design elements or omissions to look for in designs being reviewed, and recommendations for multiplexed data communication systems used in safety systems. The second area reviews pertinent aspects of communication protocol design and makes recommendations for newly designed protocols or the selection of existing protocols for safety system, information display, and non-safety control system use. The third area covers communication media selection, which differs significantly from traditional wire and cable. The recommendations for communication media extend or enhance the concerns of published IEEE standards about three subjects: data rate, imported hazards and maintainability.

  6. Data communications

    International Nuclear Information System (INIS)

    The purpose of this paper is to recommend regulatory guidance for reviewers examining computer communication systems used in nuclear power plants. The recommendations cover three areas important to these communications systems: system design, communication protocols, and communication media. The first area, system design, considers three aspects of system design--questions about architecture, specific risky design elements or omissions to look for in designs being reviewed, and recommendations for multiplexed data communication systems used in safety systems. The second area reviews pertinent aspects of communication protocol design and makes recommendations for newly designed protocols or the selection of existing protocols for safety system, information display, and non-safety control system use. The third area covers communication media selection, which differs significantly from traditional wire and cable. The recommendations for communication media extend or enhance the concerns of published IEEE standards about three subjects: data rate, imported hazards and maintainability

  7. Communication, Communication, Communication! Growth through Laboratory Instructing

    Science.gov (United States)

    Peterson, Jamie J.; DeAngelo, Samantha; Mack, Nancy; Thompson, Claudia; Cooper, Jennifer; Sesma, Arturo, Jr.

    2014-01-01

    This study examined gains undergraduate students made in their communication and collaboration skills when they served as peer teachers, i.e., laboratory instructors (LIs), for a General Psychology laboratory. Self-ratings of communication and collaboration skills were completed before and after teaching the laboratory. When compared to before the…

  8. Communication (action with communicative content).

    Science.gov (United States)

    Russo, M T

    2010-01-01

    The term Communication generally designate the transmission of a message of concepts, feelings or needs from a speaker to a receiver by means of verbal or no verbal language. The pragmatic approach to human communication has put in evidence a further implication of this concept: every behaviour therefore has a value even when it is not intentional. Recently, a more dynamic concept of communication has been elaborated where communication means communicative action. This interpretation is the starting point for the theory of the "communicative acting" and subsequently of the so called discourse ethic elaborated by J. Habermas. PMID:20499038

  9. Communicative Writing

    Institute of Scientific and Technical Information of China (English)

    彭燕

    2016-01-01

    Writing, like all other aspects of language , is communicative.Communicative writing takes an important part in English learn-ing.Communicative writing assignments train students to turn personal observations into impersonal prose , avoid value judgments unwelcome in the sciences, and write with economy and precision .In the English language classroom , however, writing often lacks this.Why?There are lots of reasons , as there are lots of ways to make the writing we do with students more communicative .

  10. COMMUNICATION SKILL

    OpenAIRE

    Madhuri Ludbe

    2014-01-01

    Effective communication helps us better understand a person or situation and enables us to resolve differences, build trust and respect, and create environments where creative ideas, problem solving, affection, and caring can flourish. By learning these effective communication skills, you can better connect with your children, friends, and coworkers. Effective communication skills are fundamental to success in many aspects of life. Many jobs require strong communication ski...

  11. Postcultural Communication?

    DEFF Research Database (Denmark)

    Jensen, Iben

    2015-01-01

    When we as scholars use the concept of intercultural communication in its classic definition, as communication between people with different cultural backgrounds, we perpetuate the notion that national differences influence communication more than other differences; in doing so, ethnic minorities...... in multicultural societies are silently/verbally excluded from national communities. The aim of the article is to develop a theoretical position, which is able to conceptualize intercultural communication in complex multicultural societies and function as a frame for empirical analysis. The...

  12. Intercompany Communication

    OpenAIRE

    Sokol, Viktor

    2013-01-01

    This translated bachelor’s study looks into the issue of communication and its functioning in the selected company. The study is divided into theoretical and practical part. The theoretical part introduces general links of mentioned problems acquired especially on the basis of analysis mentioned in specialized literature. The concept of communication, its function and form as well as process of communication and barriers in communication are explained here. Last but not least you can find her...

  13. Marketing Communication

    OpenAIRE

    Kozáková, Radka

    2013-01-01

    Marketing communication plays an important role in every competitive organization. It is an integral part of a successful sales and create a long-term relationships with customers and other public. This thesis consists of two parts. The theoretical part and a practical part. The theoretical part describes the concept of marketing mix and its components, there is also clarified the concept of communication, marketing communication and the five main components of the communication mix. An in...

  14. Communicating Effectively

    Science.gov (United States)

    The seventh module of the EPEC-O (Education in Palliative and End-of-Life Care for Oncology) Self-Study: Cultural Considerations When Caring for African Americans explores communication issues pertinent to African Americans with cancer and their health care providers, discusses strategies for culturally sensitive communication, and presents the SPIKES protocol, a practical framework for effective communication.

  15. Existential Communication.

    Science.gov (United States)

    Self, Charles C.

    Focusing on the seminal work "Being and Nothingness," this paper explores the implications of the ideas of Jean-Paul Sartre for the study of communication in society. The paper redefines communication from an existential point of view, explores some implications of this redefinition for the study of communication within the social setting, and…

  16. Allosteric inhibition of glycogen phosphorylase a by the potential antidiabetic drug 3-isopropyl 4-(2-chlorophenyl)-1,4-dihydro-1-ethyl-2-methyl-pyridine-3,5,6-tricarbo xylate.

    Science.gov (United States)

    Oikonomakos, N G; Tsitsanou, K E; Zographos, S E; Skamnaki, V T; Goldmann, S; Bischoff, H

    1999-10-01

    -terminal tail occurs, while the loop of chain containing residues 192-196 and residues 43'-49' shift to accommodate the ligand. Structural comparisons show that the T-state GPa-glucose-W1807 structure is overall more similar to the T-state GPb-W1807 complex structure than to the GPa-glucose complex structure, indicating that W1807 is able to transform GPa to the T'-like state already observed with GPb. The structures provide a rational for the potency of the inhibitor and explain GPa allosteric inhibition of activity upon W1807 binding. PMID:10548038

  17. Organizational Communication: Communication and Motivation in the Workplace

    OpenAIRE

    Sari Ramadanty; Handy Martinus

    2016-01-01

    Every human activity was basically driven by the motivation. Work motivation was a condition or an energy that directed employees to achieve organizational goals of the company. Nowadays, the development of organizational communication saw the communication as one of the most dominant and important activity in the organization and it could be able to motivate employees. The purpose of this study was to reveal how the role of the communication that occurs within the organization could give ...

  18. Identification of an allosteric pocket on human hsp70 reveals a mode of inhibition of this therapeutically important protein.

    Science.gov (United States)

    Rodina, Anna; Patel, Pallav D; Kang, Yanlong; Patel, Yogita; Baaklini, Imad; Wong, Michael J H; Taldone, Tony; Yan, Pengrong; Yang, Chenghua; Maharaj, Ronnie; Gozman, Alexander; Patel, Maulik R; Patel, Hardik J; Chirico, William; Erdjument-Bromage, Hediye; Talele, Tanaji T; Young, Jason C; Chiosis, Gabriela

    2013-12-19

    Hsp70s are important cancer chaperones that act upstream of Hsp90 and exhibit independent anti-apoptotic activities. To develop chemical tools for the study of human Hsp70, we developed a homology model that unveils a previously unknown allosteric site located in the nucleotide binding domain of Hsp70. Combining structure-based design and phenotypic testing, we discovered a previously unknown inhibitor of this site, YK5. In cancer cells, this compound is a potent and selective binder of the cytosolic but not the organellar human Hsp70s and has biological activity partly by interfering with the formation of active oncogenic Hsp70/Hsp90/client protein complexes. YK5 is a small molecule inhibitor rationally designed to interact with an allosteric pocket of Hsp70 and represents a previously unknown chemical tool to investigate cellular mechanisms associated with Hsp70. PMID:24239008

  19. Directed evolution of the tryptophan synthase β-subunit for stand-alone function recapitulates allosteric activation.

    Science.gov (United States)

    Buller, Andrew R; Brinkmann-Chen, Sabine; Romney, David K; Herger, Michael; Murciano-Calles, Javier; Arnold, Frances H

    2015-11-24

    Enzymes in heteromeric, allosterically regulated complexes catalyze a rich array of chemical reactions. Separating the subunits of such complexes, however, often severely attenuates their catalytic activities, because they can no longer be activated by their protein partners. We used directed evolution to explore allosteric regulation as a source of latent catalytic potential using the β-subunit of tryptophan synthase from Pyrococcus furiosus (PfTrpB). As part of its native αββα complex, TrpB efficiently produces tryptophan and tryptophan analogs; activity drops considerably when it is used as a stand-alone catalyst without the α-subunit. Kinetic, spectroscopic, and X-ray crystallographic data show that this lost activity can be recovered by mutations that reproduce the effects of complexation with the α-subunit. The engineered PfTrpB is a powerful platform for production of Trp analogs and for further directed evolution to expand substrate and reaction scope. PMID:26553994

  20. COMMUNICATION SKILL

    Directory of Open Access Journals (Sweden)

    Madhuri Ludbe

    2014-08-01

    Full Text Available Effective communication helps us better understand a person or situation and enables us to resolve differences, build trust and respect, and create environments where creative ideas, problem solving, affection, and caring can flourish. By learning these effective communication skills, you can better connect with your children, friends, and coworkers. Effective communication skills are fundamental to success in many aspects of life. Many jobs require strong communication skills and socially people with improved communication skills usually enjoy better interpersonal relationships with friends and family.

  1. Communication Acoustics

    DEFF Research Database (Denmark)

    Blauert, Jens

    Communication Acoustics deals with the fundamentals of those areas of acoustics which are related to modern communication technologies. Due to the advent of digital signal processing and recording in acoustics, these areas have enjoyed an enormous upswing during the last 4 decades. The book...... the book a source of valuable information for those who want to improve or refresh their knowledge in the field of communication acoustics - and to work their way deeper into it. Due to its interdisciplinary character Communication Acoustics is bound to attract readers from many different areas, such as......: acoustics, cognitive science, speech science, and communication technology....

  2. Virtual Screening and Molecular Dynamics Study of Potential Negative Allosteric Modulators of mGluR1 from Chinese Herbs

    Directory of Open Access Journals (Sweden)

    Ludi Jiang

    2015-07-01

    Full Text Available The metabotropic glutamate subtype 1 (mGluR1, a member of the metabotropic glutamate receptors, is a therapeutic target for neurological disorders. However, due to the lower subtype selectivity of mGluR1 orthosteric compounds, a new targeted strategy, known as allosteric modulators research, is needed for the treatment of mGluR1-related diseases. Recently, the structure of the seven-transmembrane domain (7TMD of mGluR1 has been solved, which reveals the binding site of allosteric modulators and provides an opportunity for future subtype-selectivity drug design. In this study, a series of computer-aided drug design methods were utilized to discover potential mGluR1 negative allosteric modulators (NAMs. Pharmacophore models were constructed based on three different structure types of mGluR1 NAMs. After validation using the built-in parameters and test set, the optimal pharmacophore model of each structure type was selected and utilized as a query to screen the Traditional Chinese Medicine Database (TCMD. Then, three different hit lists of compounds were obtained. Molecular docking was used based on the latest crystal structure of mGluR1-7TMD to further filter these hits. As a compound with high QFIT and LibDock Score was preferred, a total of 30 compounds were retained. MD simulation was utilized to confirm the stability of potential compounds binding. From the computational results, thesinine-4ʹ-O-β-d-glucoside, nigrolineaxanthone-P and nodakenin might exhibit negative allosteric moderating effects on mGluR1. This paper indicates the applicability of molecular simulation technologies for discovering potential natural mGluR1 NAMs from Chinese herbs.

  3. The positive allosteric GABAB receptor modulator rac-BHFF enhances baclofen-mediated analgesia in neuropathic mice.

    Science.gov (United States)

    Zemoura, Khaled; Ralvenius, William T; Malherbe, Pari; Benke, Dietmar

    2016-09-01

    Neuropathic pain is associated with impaired inhibitory control of spinal dorsal horn neurons, which are involved in processing pain signals. The metabotropic GABAB receptor is an important component of the inhibitory system and is highly expressed in primary nociceptors and intrinsic dorsal horn neurons to control their excitability. Activation of GABAB receptors with the orthosteric agonist baclofen effectively reliefs neuropathic pain but is associated with severe side effects that prevent its widespread application. The recently developed positive allosteric GABAB receptor modulators lack most of these side effects and are therefore promising drugs for the treatment of pain. Here we tested the high affinity positive allosteric modulator rac-BHFF for its ability to relief neuropathic pain induced by chronic constriction of the sciatic nerve in mice. rac-BHFF significantly increased the paw withdrawal threshold to mechanical stimulation in healthy mice, indicating an endogenous GABABergic tone regulating the sensitivity to mechanical stimuli. Surprisingly, rac-BHFF displayed no analgesic activity in neuropathic mice although GABAB receptor expression was not affected in the dorsal horn as shown by quantitative receptor autoradiography. However, activation of spinal GABAB receptors by intrathecal injection of baclofen reduced hyperalgesia and its analgesic effect was considerably potentiated by co-application of rac-BHFF. These results indicate that under conditions of neuropathic pain the GABAergic tone is too low to provide a basis for allosteric modulation of GABAB receptors. However, allosteric modulators would be well suited as an add-on to reduce the dose of baclofen required to achieve analgesia. PMID:27108932

  4. Synthesis of a Series of Novel 3,9-Disubstituted Phenanthrenes as Analogues of Known NMDA Receptor Allosteric Modulators

    OpenAIRE

    Irvine, Mark W.; Fang, Guangyu; Eaves, Richard; Mayo-Martin, Maria B.; Burnell, Erica S.; Costa, Blaise M.; Culley, Georgia R.; Volianskis, Arturas; Collingridge, Graham L; Monaghan, Daniel T.; Jane, David E.

    2015-01-01

    9-Substituted phenanthrene-3-carboxylic acids have been reported to have allosteric modulatory activity at the NMDA receptor. This receptor is activated by the excitatory neurotransmitter L-glutamate and has been implicated in a range of neurological disorders such as schizophrenia, epilepsy and chronic pain and neurodegenerative disorders such as Alzheimer’s disease. Herein, the convenient synthesis of a wide range of novel 3,9-disubstituted phenanthrene derivatives starting from a few commo...

  5. Allosteric vs. spontaneous exit-site (E-site) tRNA dissociation early in protein synthesis

    OpenAIRE

    Chen, Chunlai; Stevens, Benjamin; Kaur, Jaskiran; Smilansky, Zeev; Cooperman, Barry S.; Goldman, Yale E.

    2011-01-01

    During protein synthesis, deacylated transfer RNAs leave the ribosome via an exit (E) site after mRNA translocation. How the ribosome regulates tRNA dissociation and whether functional linkages between the aminoacyl (A) and E sites modulate the dynamics of protein synthesis have long been debated. Using single molecule fluorescence resonance energy transfer experiments, we find that, during early cycles of protein elongation, tRNAs are often held in the E site until being allosterically relea...

  6. For a communication as opening and impossibility

    OpenAIRE

    Maurício Liesen

    2012-01-01

    The object of this study is a form of communication that is not a transmission of signs, an expression or an exchange of meanings. A communication’s concept extracted from the books of Maurice Blanchot and Emmanuel Levinas: communication as opening and welcoming (Levinas) and communication as a plural word (Blanchot). The communicational process occurs only when it escapes from power and when it announces its own impossibility: communication as existential dimension.

  7. Data communications

    International Nuclear Information System (INIS)

    The contents of this book are notion of data communications : summary on data communication, data transmission, data communications system, data transmission technology, data conversion, data link control and control over error of data transmission and exchange of data communications network in the first part, computer communications network architecture : data communications architecture, OSI model, lower layer of OSI model, upper layer of OSI model and distributed surroundings in the second part, data information networking : LAN, FDDI, 100 Base T, DQDB and Frame Relay in the third part, Public Network : PSDN, N-ISDN, B-ISDN in the fourth part, internet and PC communication : emulator program, Binary file, BBS, E-mail service and user on-line service in the last part.

  8. Living antennas on communication satellites

    DEFF Research Database (Denmark)

    Lumholt, Michael

    2003-01-01

    Crises change the global pattern of communication. The communications problems occur because the satellites are optimized to cover specific geographic areas, and these areas cannot be altered once the satellites are in Earth orbit. An effective solution to the problem is to equip communication sa...... satellites with "living" antennas that can adjust their radiation coverage areas according to the new demands. The development of living antennas is, therefore, among the focus areas identified and supported by the European Space Agency, ESA....

  9. Fructose-1,6-Bisphosphate Is an Allosteric Activator of Pyrophosphate:Fructose-6-Phosphate 1-Phosphotransferase.

    Science.gov (United States)

    Nielsen, T. H.

    1995-05-01

    The activity of highly purified pyrophosphate:fructose-6-phosphate 1-phosphotransferase (PFP) from barley (Hordeum vulgare) leaves was studied under conditions where the catalyzed reaction was allowed to approach equilibrium. The activity of PFP was monitored by determining the changes in the levels of fructose-6-phosphate, orthophosphate, and fructose-1,6-bisphosphate (Fru-1,6-bisP). Under these conditions PFP activity was not dependent on activation by fructose-2,6-bisphosphate (Fru-2,6-bisP). Inclusion of aldolase in the reaction mixture temporarily restored the dependence of PFP on Fru-2,6-bisP. Alternatively, PFP was activated by Fru-1,6-bisP in the presence of aldolase. It is concluded that Fru-1,6-bisP is an allosteric activator of barley PFP, which can substitute for Fru-2,6-bisP as an activator. A significant activation was observed at a concentration of 5 to 25 [mu]M Fru-1,6-bisP, which demonstrates that the allosteric site of barley PFP has a very high affinity for Fru-1,6-bisP. The high affinity for Fru-1,6-bisP at the allosteric site suggests that the observed activation of PFP by Fru-1,6-bisP constitutes a previously unrecognized in vivo regulation mechanism. PMID:12228454

  10. An allosteric modulator of HIV-1 protease shows equipotent inhibition of wild-type and drug-resistant proteases.

    Science.gov (United States)

    Ung, Peter M-U; Dunbar, James B; Gestwicki, Jason E; Carlson, Heather A

    2014-08-14

    NMR and MD simulations have demonstrated that the flaps of HIV-1 protease (HIV-1p) adopt a range of conformations that are coupled with its enzymatic activity. Previously, a model was created for an allosteric site located between the flap and the core of HIV-1p, called the Eye site (Biopolymers 2008, 89, 643-652). Here, results from our first study were combined with a ligand-based, lead-hopping method to identify a novel compound (NIT). NIT inhibits HIV-1p, independent of the presence of an active-site inhibitor such as pepstatin A. Assays showed that NIT acts on an allosteric site other than the dimerization interface. MD simulations of the ligand-protein complex show that NIT stably binds in the Eye site and restricts the flaps. That bound state of NIT is consistent with a crystal structure of similar fragments bound in the Eye site (Chem. Biol. Drug Des. 2010, 75, 257-268). Most importantly, NIT is equally potent against wild-type and a multidrug-resistant mutant of HIV-1p, which highlights the promise of allosteric inhibitors circumventing existing clinical resistance. PMID:25062388

  11. WHERE DOES WATERBORNE GIARDIASIS OCCUR, AND WHY

    Science.gov (United States)

    Over 60 outbreaks of waterborne giardiasis occurred in the United States between 1965 and 1982, mainly in the Northeast, the Rocky Mountain states, and the Pacific states. Outbreaks most often occurred as a result of inadequate or interrupted treatment. Disinfection problems and ...

  12. Coaching Communication Partners: A Preliminary Investigation of Communication Intervention during Mealtime in Rett Syndrome

    Science.gov (United States)

    Bartolotta, Theresa E.; Remshifski, Patricia A.

    2013-01-01

    Rett syndrome (RTT) occurs primarily in females and is characterized by deficits in cognition, communication, hand use and ambulation. This quasi-experimental study explored the use of a coaching program to increase communicative interactions between girls with RTT and their communication partners. Communication coaching strategies were provided…

  13. Communication system for emergency

    International Nuclear Information System (INIS)

    People are apprehensive that a strong earthquake with a magnitude of nearly 8 may occur in Tokai area. The whole area of Shizuoka Prefecture has been specified as the specially strengthened region for earthquake disaster measures. This report outlines the communication system for emergency with respect to atomic disaster caused by an earthquake. Previously, wireless receiving system is stationed in the whole area to simultaneously inform the related news to the residents and so, communications with them are possible at any time by using the system. Since mobile wireless receiving sets are stationed in all town halls, self defense organizations and all the places of refuge, mutual communications are possible. These communication system can be utilized for either earthquake or nuclear disaster. Further, Shizuoka general information network system has been established as a communication system for anti-disaster organization and a wireless network via a communication satellite, ''super bird'' has been constructed in addition to the ground network. Therefore, the two communication routes became usable at emergency and the systems are available in either of nuclear disaster or earthquake. (M.N.)

  14. Communication system for emergency

    Energy Technology Data Exchange (ETDEWEB)

    Ajioka, Yoshiteru [Shizuoka Prefecture (Japan)

    1996-12-01

    People are apprehensive that a strong earthquake with a magnitude of nearly 8 may occur in Tokai area. The whole area of Shizuoka Prefecture has been specified as the specially strengthened region for earthquake disaster measures. This report outlines the communication system for emergency with respect to atomic disaster caused by an earthquake. Previously, wireless receiving system is stationed in the whole area to simultaneously inform the related news to the residents and so, communications with them are possible at any time by using the system. Since mobile wireless receiving sets are stationed in all town halls, self defense organizations and all the places of refuge, mutual communications are possible. These communication system can be utilized for either earthquake or nuclear disaster. Further, Shizuoka general information network system has been established as a communication system for anti-disaster organization and a wireless network via a communication satellite, ``super bird`` has been constructed in addition to the ground network. Therefore, the two communication routes became usable at emergency and the systems are available in either of nuclear disaster or earthquake. (M.N.)

  15. The energetics of allosteric regulation of ADP release from myosin heads.

    Science.gov (United States)

    Jackson, Del R; Baker, Josh E

    2009-06-28

    Myosin molecules are involved in a wide range of transport and contractile activities in cells. A single myosin head functions through its ATPase reaction as a force generator and as a mechanosensor, and when two or more myosin heads work together in moving along an actin filament, the interplay between these mechanisms contributes to collective myosin behaviors. For example, the interplay between force-generating and force-sensing mechanisms coordinates the two heads of a myosin V molecule in its hand-over-hand processive stepping along an actin filament. In muscle, it contributes to the Fenn effect and smooth muscle latch. In both examples, a key force-sensing mechanism is the regulation of ADP release via interhead forces that are generated upon actin-myosin binding. Here we present a model describing the mechanism of allosteric regulation of ADP release from myosin heads as a change, DeltaDeltaG(-D), in the standard free energy for ADP release that results from the work, Deltamicro(mech), performed by that myosin head upon ADP release, or DeltaDeltaG(-D) = Deltamicro(mech). We show that this model is consistent with previous measurements for strain-dependent kinetics of ADP release in both myosin V and muscle myosin II. The model makes explicit the energetic cost of accelerating ADP release, showing that acceleration of ADP release during myosin V processivity requires approximately 4 kT of energy whereas the energetic cost for accelerating ADP release in a myosin II-based actin motility assay is only approximately 0.4 kT. The model also predicts that the acceleration of ADP release involves a dissipation of interhead forces. To test this prediction, we use an in vitro motility assay to show that the acceleration of ADP release from both smooth and skeletal muscle myosin II correlates with a decrease in interhead force. Our analyses provide clear energetic constraints for models of the allosteric regulation of ADP release and provide novel, testable insights

  16. Positive allosteric modulation of TRPV1 as a novel analgesic mechanism

    Directory of Open Access Journals (Sweden)

    Lebovitz Evan E

    2012-09-01

    Full Text Available Abstract Background The prevalence of long-term opiate use in treating chronic non-cancer pain is increasing, and prescription opioid abuse and dependence are a major public health concern. To explore alternatives to opioid-based analgesia, the present study investigates a novel allosteric pharmacological approach operating through the cation channel TRPV1. This channel is highly expressed in subpopulations of primary afferent unmyelinated C- and lightly-myelinated Aδ-fibers that detect low and high rates of noxious heating, respectively, and it is also activated by vanilloid agonists and low pH. Sufficient doses of exogenous vanilloid agonists, such as capsaicin or resiniferatoxin, can inactivate/deactivate primary afferent endings due to calcium overload, and we hypothesized that positive allosteric modulation of agonist-activated TRPV1 could produce a selective, temporary inactivation of nociceptive nerve terminals in vivo. We previously identified MRS1477, a 1,4-dihydropyridine that potentiates vanilloid and pH activation of TRPV1 in vitro, but displays no detectable intrinsic agonist activity of its own. To study the in vivo effects of MRS1477, we injected the hind paws of rats with a non-deactivating dose of capsaicin, MRS1477, or the combination. An infrared diode laser was used to stimulate TRPV1-expressing nerve terminals and the latency and intensity of paw withdrawal responses were recorded. qRT-PCR and immunohistochemistry were performed on dorsal root ganglia to examine changes in gene expression and the cellular specificity of such changes following treatment. Results Withdrawal responses of the capsaicin-only or MRS1477-only treated paws were not significantly different from the untreated, contralateral paws. However, rats treated with the combination of capsaicin and MRS1477 exhibited increased withdrawal latency and decreased response intensity consistent with agonist potentiation and inactivation or lesion of TRPV1-containing

  17. Structural Features of Ion Transport and Allosteric Regulation in Sodium-Calcium Exchanger (NCX) Proteins.

    Science.gov (United States)

    Giladi, Moshe; Tal, Inbal; Khananshvili, Daniel

    2016-01-01

    Na(+)/Ca(2+) exchanger (NCX) proteins extrude Ca(2+) from the cell to maintain cellular homeostasis. Since NCX proteins contribute to numerous physiological and pathophysiological events, their pharmacological targeting has been desired for a long time. This intervention remains challenging owing to our poor understanding of the underlying structure-dynamic mechanisms. Recent structural studies have shed light on the structure-function relationships underlying the ion-transport and allosteric regulation of NCX. The crystal structure of an archaeal NCX (NCX_Mj) along with molecular dynamics simulations and ion flux analyses, have assigned the ion binding sites for 3Na(+) and 1Ca(2+), which are being transported in separate steps. In contrast with NCX_Mj, eukaryotic NCXs contain the regulatory Ca(2+)-binding domains, CBD1 and CBD2, which affect the membrane embedded ion-transport domains over a distance of ~80 Å. The Ca(2+)-dependent regulation is ortholog, isoform, and splice-variant dependent to meet physiological requirements, exhibiting either a positive, negative, or no response to regulatory Ca(2+). The crystal structures of the two-domain (CBD12) tandem have revealed a common mechanism involving a Ca(2+)-driven tethering of CBDs in diverse NCX variants. However, dissociation kinetics of occluded Ca(2+) (entrapped at the two-domain interface) depends on the alternative-splicing segment (at CBD2), thereby representing splicing-dependent dynamic coupling of CBDs. The HDX-MS, SAXS, NMR, FRET, equilibrium (45)Ca(2+) binding and stopped-flow techniques provided insights into the dynamic mechanisms of CBDs. Ca(2+) binding to CBD1 results in a population shift, where more constraint conformational states become highly populated without global conformational changes in the alignment of CBDs. This mechanism is common among NCXs. Recent HDX-MS studies have demonstrated that the apo CBD1 and CBD2 are stabilized by interacting with each other, while Ca(2+) binding to CBD1

  18. Assessing the structural conservation of protein pockets to study functional and allosteric sites: implications for drug discovery

    Directory of Open Access Journals (Sweden)

    Daura Xavier

    2010-03-01

    Full Text Available Abstract Background With the classical, active-site oriented drug-development approach reaching its limits, protein ligand-binding sites in general and allosteric sites in particular are increasingly attracting the interest of medicinal chemists in the search for new types of targets and strategies to drug development. Given that allostery represents one of the most common and powerful means to regulate protein function, the traditional drug discovery approach of targeting active sites can be extended by targeting allosteric or regulatory protein pockets that may allow the discovery of not only novel drug-like inhibitors, but activators as well. The wealth of available protein structural data can be exploited to further increase our understanding of allosterism, which in turn may have therapeutic applications. A first step in this direction is to identify and characterize putative effector sites that may be present in already available structural data. Results We performed a large-scale study of protein cavities as potential allosteric and functional sites, by integrating publicly available information on protein sequences, structures and active sites for more than a thousand protein families. By identifying common pockets across different structures of the same protein family we developed a method to measure the pocket's structural conservation. The method was first parameterized using known active sites. We characterized the predicted pockets in terms of sequence and structural conservation, backbone flexibility and electrostatic potential. Although these different measures do not tend to correlate, their combination is useful in selecting functional and regulatory sites, as a detailed analysis of a handful of protein families shows. We finally estimated the numbers of potential allosteric or regulatory pockets that may be present in the data set, finding that pockets with putative functional and effector characteristics are widespread across

  19. Communication theory

    DEFF Research Database (Denmark)

    Stein, Irene F.; Stelter, Reinhard

    2011-01-01

    ascribe specific meanings to their experiences, their actions in life or work, and their interactions. Meaning is reshaped, adapted, and transformed in every communication encounter. Furthermore, meaning is cocreated in dialogues or in communities of practice, such as in teams at a workplace or in school......Communication theory covers a wide variety of theories related to the communication process (Littlejohn, 1999). Communication is not simply an exchange of information, in which we have a sender and a receiver. This very technical concept of communication is clearly outdated; a human being...... is not a data processing device. In this chapter, communication is understood as a process of shared meaning-making (Bruner, 1990). Human beings interpret their environment, other people, and themselves on the basis of their dynamic interaction with the surrounding world. Meaning is essential because people...

  20. Drill machine guidance using natural occurring radiation

    International Nuclear Information System (INIS)

    A drilling machine guidance system is described which uses only the naturally occuring radiation within the seam or stratum of interest. The apparatus can be used for guiding horizontal drilling machines through coal seams and the like. (U.K.)

  1. Human external ophthalmomyiasis occurring in Barbados.

    Science.gov (United States)

    Levett, P N; Brooker, L; Reifer, C; Prussia, P R; Eberhard, M L

    2004-06-01

    Human infection with the sheep nasal botfly Oestrus ovis occurs sporadically. In most cases, there is a history of a strike in the eye by the adult fly. Human O. ovis has been reported rarely from the Americas. We report the first case of O. ovis infection in the Caribbean region, which occurred in an urban area of Barbados. The patient responded to removal of the larvae from the conjunctiva and symptomatic treatment. PMID:15352754

  2. Crisis communication

    OpenAIRE

    Franěk, Petr

    2011-01-01

    This thesis looks into the crisis communication of the flood authorities and of the integrated rescue system bodies with the population in the city of Pilsen during the floods in 2002. Its main objective is to identify the control and functionality weaknesses of the communication and warning system for the population based on an analysis of the course of crisis communication and the results of a survey and suggest new locations and elements of this system within the area of the Statutory city...

  3. Scholarly Communications

    OpenAIRE

    Das, Anup-Kumar

    2015-01-01

    Researchers, scholars and scientists main business is scholarly communication. We communicate about our work to others, as we push the boundaries of what we know and the society knows. We question established notions and truths about science. We share our findings with others, and in a way that is popularly known as scholarly communication which emerged with the publication of first journal in 1665. However, the term gained popularity only in the 1970s, as access to peer reviewed and scholarl...

  4. Marketing Communications

    OpenAIRE

    Svatoňová, Michala

    2012-01-01

    This diploma thesis touches the concept of marketing in the general, then is specially focused on the marketing communication and finally evaluates the situation of a selected international company Raytheon Professional Services with regard to implementation of marketing communication plan. Thesis is divided into two main parts. The first part is concerned about the theoretical background of marketing and marketing communication, marketing mix in order to gain the knowledge needed for set...

  5. Communication Strategy

    OpenAIRE

    Marková, Michaela

    2012-01-01

    This bachelor thesis concentrates on a marketing communications, which are explained using the firm RE/MAX Consult. It also deals with the influence, which has RE/MAX and RE/MAX Czech republic on the marketing communications of the chosen company. Theoretical part of this bachelor thesis concerns with the explanation of the basic terms of the marketing, the marketing communications and the marketing mix. The second part focuses on the company RE/MAX Consult, the analysis of its marketin...

  6. Conscious Communication

    OpenAIRE

    Augoustakis, Louisa

    2013-01-01

    This project researches the concept of conscious communication through Marshall Rosenberg’s definition of Nonviolent Communication, it accounts for a concept derived from the nonviolent communication, Beliving, founded by Lisa von Schmalensee Magnússon. Rosenberg’s definitions of judgmental and violent language are utilised in an analysis of the first 2008 presidential debate. The analysis includes relevant rhetoric devices in relation to violent language forms. The discussion revolves around...

  7. Crisis Communication

    OpenAIRE

    Bernth, Camilla

    2013-01-01

    This project deals with the usage of crisis communication in a case study of SAS and Maersk, when they were both indicted for illegally fixing prices on cargo airlines in 2001. This is done through analyzing the messages and publicity of the two companies in the media and applying theoretical tools from communication. The theoretical tools are divided into rhetorical and crisis communication theory, where framing, persuasion and issue management is applied. The project sheds light on how ...

  8. Consequences of Co-Occurring Attention-Deficit/Hyperactivity Disorder on Children's Language Impairments

    Science.gov (United States)

    Redmond, Sean M.; Ash, Andrea C.; Hogan, Tiffany P.

    2015-01-01

    Purpose: Co-occurring attention-deficit/hyperactivity disorder (ADHD) and communication disorders represent a frequently encountered challenge for school-based practitioners. The purpose of the present study was to examine in more detail the clinical phenomenology of co-occurring ADHD and language impairments (LIs). Method: Measures of nonword…

  9. Negative Allosteric Modulation of the mGluR5 Receptor Reduces Repetitive Behaviors and Rescues Social Deficits in Mouse Models of Autism

    Science.gov (United States)

    Silverman, Jill L.; Smith, Daniel G.; Sukoff Rizzo, Stacey J.; Karras, Michael N.; Turner, Sarah M.; Tolu, Seda S.; Bryce, Dianne K.; Smith, Deborah L.; Fonseca, Kari; Ring, Robert H.; Crawley, Jacqueline N.

    2016-01-01

    Neurodevelopmental disorders such as autism and fragile X syndrome were long thought to be medically untreatable, on the assumption that brain dysfunctions were immutably hardwired before diagnosis. Recent revelations that many cases of autism are caused by mutations in genes that control the ongoing formation and maturation of synapses have challenged this dogma. Antagonists of metabotropic glutamate receptor subtype 5 (mGluR5), which modulate excitatory neurotransmission, are in clinical trials for fragile X syndrome, a major genetic cause of intellectual disabilities. About 30% of patients with fragile X syndrome meet the diagnostic criteria for autism. Reasoning by analogy, we considered the mGluR5 receptor as a potential target for intervention in autism. We used BTBR T+tf/J (BTBR) mice, an established model with robust behavioral phenotypes relevant to the three diagnostic behavioral symptoms of autism—unusual social interactions, impaired communication, and repetitive behaviors—to probe the efficacy of a selective negative allosteric modulator of the mGluR5 receptor, GRN-529. GRN-529 reduced repetitive behaviors in three cohorts of BTBR mice at doses that did not induce sedation in control assays of open field locomotion. In addition, the same nonsedating doses reduced the spontaneous stereotyped jumping that characterizes a second inbred strain of mice, C58/J. Further, GRN-529 partially reversed the striking lack of sociability in BTBR mice on some parameters of social approach and reciprocal social interactions. These findings raise the possibility that a single targeted pharmacological intervention may alleviate multiple diagnostic behavioral symptoms of autism. PMID:22539775

  10. Ultrasensitivity and heavy-metal selectivity of the allosterically modulated MerR transcription complex

    International Nuclear Information System (INIS)

    The MerR metalloregulatory protein is a heavy-metal receptor that functions as the repressor and Hg(II)-responsive transcription activator of the prokaryotic mercury-resistance (mer) genes. The authors demonstrate that this allosterically modulated regulatory protein is sensitive to HgCl2 concentrations of 1.0 ± 0.3 x 10-8 M in the presence of 1.0 x 10-3 M dithiothreitol for half-maximal induction of transcription of the mer promoter by Escherichia coli RNA polymerase in vitro. Transcription mediated by MerR increases from 10% to 90% of maximum in response to a 7-fold change in concentration of HgCl2, consistent with a threshold phenomenon known as ultrasensitivity. In addition, MerR exhibits a high degree of selectivity. Cd(II), Zn(II), Ag(I), Au(I), and Au(III) have been found to partially stimulate transcription in the presence of MerR, but concentrations at least two to three orders of magnitude greater than for Hg(II) are required. The molecular basis of the ultrasensitivity and selectivity phenomena are postulated to arise from the unusual topology of the transcription complex and a rare trigonal mercuric ion coordination environment, respectively. This mercuric ion-induced switch is to our knowledge the only known example of ultrasensitivity in a signal-responsive transcription mechanism

  11. Comparison of crystal and solution hemoglobin binding of selected antigelling agents and allosteric modifiers

    International Nuclear Information System (INIS)

    This paper details comprehensive binding studies (solution and X-ray) of human hemoglobin A with a group of halogenated carboxylic acids that were investigated as potential antisickling agents. It is, to our knowledge, the first study to compare solution and crystal binding for a series of compounds under similar high-salt conditions used for cocrystallization. The compounds include [(3,4-dichlorobenzyl)oxy]acetic acid, [(p-bromobenzyl)oxy]acetic acid, clofibric acid, and bezafibrate. The location and stereochemistry of binding sites have been established by X-ray crystallography, while the number of binding sites and affinity constants were measured by using equilibrium dialysis. The observed crystal structures are consistent with the binding observed in solution and that the number of binding sites is independent of salt concentration, while the binding constant increases with increasing salt concentration. The studies also reveal that relatively small changes in the chemical structure of a drug molecule can result in entirely different binding sites on the protein. Moreover, the X-ray studies provide a possible explanation for the multiplicity in function exhibited by these compounds as allosteric modulators and/or antisickling agents. Finally, the studies indicate that these compounds bind differently to the R and T states of hemoglobin, and observation of special significance to the original design of these agents

  12. Structural basis for allosteric regulation of human ribonucleotide reductase by nucleotide-induced oligomerization

    Energy Technology Data Exchange (ETDEWEB)

    Fairman, James Wesley; Wijerathna, Sanath Ranjan; Ahmad, Md Faiz; Xu, Hai; Nakano, Ryo; Jha, Shalini; Prendergast, Jay; Welin, R. Martin; Flodin, Susanne; Roos, Annette; Nordlund, Pär; Li, Zongli; Walz, Thomas; Dealwis, Chris Godfrey (Case Western); (Harvard-Med); (Karolinska); (Tennessee-K)

    2011-07-25

    Ribonucleotide reductase (RR) is an {alpha}{sub n}{beta}{sub n} (RR1-RR2) complex that maintains balanced dNTP pools by reducing NDPs to dNDPs. RR1 is the catalytic subunit, and RR2 houses the free radical required for catalysis. RR is allosterically regulated by its activator ATP and its inhibitor dATP, which regulate RR activity by inducing oligomerization of RR1. Here, we report the first X-ray structures of human RR1 bound to TTP alone, dATP alone, TTP-GDP, TTP-ATP, and TTP-dATP. These structures provide insights into regulation of RR by ATP or dATP. At physiological dATP concentrations, RR1 forms inactive hexamers. We determined the first X-ray structure of the RR1-dATP hexamer and used single-particle electron microscopy to visualize the {alpha}{sub 6}-{beta}{beta}'-dATP holocomplex. Site-directed mutagenesis and functional assays confirm that hexamerization is a prerequisite for inhibition by dATP. Our data indicate a mechanism for regulating RR activity by dATP-induced oligomerization.

  13. Allosteric effects in binuclear homo- and heterometallic triple-stranded lanthanide podates.

    Science.gov (United States)

    Ryan, Patrick E; Canard, Gabriel; Koeller, Sylvain; Bocquet, Bernard; Piguet, Claude

    2012-09-17

    This work illustrates a simple approach for deciphering and exploiting the various free energy contributions to the global complexation process leading to the binuclear triple-stranded podates [Ln(2)(L9)](6+) (Ln is a trivalent lanthanide). Despite the larger microscopic affinities exhibited by the binding sites for small Ln(3+), the stability constants measured for [Ln(2)(L9)](6+) decrease along the lanthanide series; a phenomenon which can be ascribed to the severe enthalpic penalty accompanying the intramolecular cyclization around small Ln(III), combined with increasing anticooperative allosteric interligand interactions. Altogether, the microscopic thermodynamic characteristics predict β(1,1,1)(La,Lu,L9)/β(1,1,1)(Lu,La,L9) = 145 for the ratio of the formation constants of the target heterobimetallic [LaLu(L9)](6+) and [LuLa(L9)](6+) microspecies, a value in line with the quantitative preparation (>90%) of [LaLu(L9)](6+) at millimolar concentrations. Preliminary NMR titrations indeed confirm the rare thermodynamic programming of a pure heterometallic f-f' complex. PMID:22946598

  14. GABAB receptor as therapeutic target for drug addiction: from baclofen to positive allosteric modulators

    Directory of Open Access Journals (Sweden)

    Roberta Agabio

    2015-04-01

    Full Text Available The present paper summarizes experimental and clinical data indicating the therapeutic potential of the GABAB receptor agonist, baclofen, in the treatment of alcohol use disorder (AUD and substance use disorder (SUD. Multiple preclinical studies have demonstrated the ability of baclofen to suppress alcohol drinking (including binge- and relapse-like drinking, oral alcohol self-administration, and intravenous self-administration of cocaine, nicotine, amphetamine, methamphetamine, morphine, and heroin in rodents. Some randomized, controlled trials (RCTs and case reports support the efficacy of baclofen in suppressing alcohol consumption, craving for alcohol, and alcohol withdrawal symptomatology in alcohol-dependent patients. Data from RCTs and open studies investigating baclofen efficacy on SUD are currently less conclusive. Interest in testing high doses of baclofen in AUD and SUD treatment has recently emerged. Preclinical research has extended the anti-addictive properties of baclofen to positive allosteric modulators of the GABAB receptor (GABAB PAMs. In light of their more favourable side effect profile (compared to baclofen, GABAB PAMs may represent a major step forward in a GABAB receptor-based pharmacotherapy of AUD and SUD.

  15. An allosteric model of the inositol trisphosphate receptor with nonequilibrium binding

    International Nuclear Information System (INIS)

    The inositol trisphosphate receptor (IPR) is a crucial ion channel that regulates the Ca2+ influx from the endoplasmic reticulum (ER) to the cytoplasm. A thorough study of the IPR channel contributes to a better understanding of calcium oscillations and waves. It has long been observed that the IPR channel is a typical biological system which performs adaptation. However, recent advances on the physical essence of adaptation show that adaptation systems with a negative feedback mechanism, such as the IPR channel, must break detailed balance and always operate out of equilibrium with energy dissipation. Almost all previous IPR models are equilibrium models assuming detailed balance and thus violate the dissipative nature of adaptation. In this article, we constructed a nonequilibrium allosteric model of single IPR channels based on the patch-clamp experimental data obtained from the IPR in the outer membranes of isolated nuclei of the Xenopus oocyte. It turns out that our model reproduces the patch-clamp experimental data reasonably well and produces both the correct steady-state and dynamic properties of the channel. Particularly, our model successfully describes the complicated bimodal [Ca2+] dependence of the mean open duration at high [IP3], a steady-state behavior which fails to be correctly described in previous IPR models. Finally, we used the patch-clamp experimental data to validate that the IPR channel indeed breaks detailed balance and thus is a nonequilibrium system which consumes energy. (paper)

  16. The condensed chromatin fiber: an allosteric chemo-mechanical machine for signal transduction and genome processing

    International Nuclear Information System (INIS)

    Allostery is a key concept of molecular biology which refers to the control of an enzyme activity by an effector molecule binding the enzyme at another site rather than the active site (allos = other in Greek). We revisit here allostery in the context of chromatin and argue that allosteric principles underlie and explain the functional architecture required for spacetime coordination of gene expression at all scales from DNA to the whole chromosome. We further suggest that this functional architecture is provided by the chromatin fiber itself. The structural, mechanical and topological features of the chromatin fiber endow chromosomes with a tunable signal transduction from specific (or nonspecific) effectors to specific (or nonspecific) active sites. Mechanical constraints can travel along the fiber all the better since the fiber is more compact and regular, which speaks in favor of the actual existence of the (so-called 30 nm) chromatin fiber. Chromatin fiber allostery reconciles both the physical and biochemical approaches of chromatin. We illustrate this view with two supporting specific examples. Moreover, from a methodological point of view, we suggest that the notion of chromatin fiber allostery is particularly relevant for systemic approaches. Finally we discuss the evolutionary power of allostery in the context of chromatin and its relation to modularity. (perspective)

  17. Allosteric inhibition of SHP2 phosphatase inhibits cancers driven by receptor tyrosine kinases.

    Science.gov (United States)

    Chen, Ying-Nan P; LaMarche, Matthew J; Chan, Ho Man; Fekkes, Peter; Garcia-Fortanet, Jorge; Acker, Michael G; Antonakos, Brandon; Chen, Christine Hiu-Tung; Chen, Zhouliang; Cooke, Vesselina G; Dobson, Jason R; Deng, Zhan; Fei, Feng; Firestone, Brant; Fodor, Michelle; Fridrich, Cary; Gao, Hui; Grunenfelder, Denise; Hao, Huai-Xiang; Jacob, Jaison; Ho, Samuel; Hsiao, Kathy; Kang, Zhao B; Karki, Rajesh; Kato, Mitsunori; Larrow, Jay; La Bonte, Laura R; Lenoir, Francois; Liu, Gang; Liu, Shumei; Majumdar, Dyuti; Meyer, Matthew J; Palermo, Mark; Perez, Lawrence; Pu, Minying; Price, Edmund; Quinn, Christopher; Shakya, Subarna; Shultz, Michael D; Slisz, Joanna; Venkatesan, Kavitha; Wang, Ping; Warmuth, Markus; Williams, Sarah; Yang, Guizhi; Yuan, Jing; Zhang, Ji-Hu; Zhu, Ping; Ramsey, Timothy; Keen, Nicholas J; Sellers, William R; Stams, Travis; Fortin, Pascal D

    2016-07-01

    The non-receptor protein tyrosine phosphatase SHP2, encoded by PTPN11, has an important role in signal transduction downstream of growth factor receptor signalling and was the first reported oncogenic tyrosine phosphatase. Activating mutations of SHP2 have been associated with developmental pathologies such as Noonan syndrome and are found in multiple cancer types, including leukaemia, lung and breast cancer and neuroblastoma. SHP2 is ubiquitously expressed and regulates cell survival and proliferation primarily through activation of the RAS–ERK signalling pathway. It is also a key mediator of the programmed cell death 1 (PD-1) and B- and T-lymphocyte attenuator (BTLA) immune checkpoint pathways. Reduction of SHP2 activity suppresses tumour cell growth and is a potential target of cancer therapy. Here we report the discovery of a highly potent (IC50 = 0.071 μM), selective and orally bioavailable small-molecule SHP2 inhibitor, SHP099, that stabilizes SHP2 in an auto-inhibited conformation. SHP099 concurrently binds to the interface of the N-terminal SH2, C-terminal SH2, and protein tyrosine phosphatase domains, thus inhibiting SHP2 activity through an allosteric mechanism. SHP099 suppresses RAS–ERK signalling to inhibit the proliferation of receptor-tyrosine-kinase-driven human cancer cells in vitro and is efficacious in mouse tumour xenograft models. Together, these data demonstrate that pharmacological inhibition of SHP2 is a valid therapeutic approach for the treatment of cancers. PMID:27362227

  18. Comparison of crystal and solution hemoglobin binding of selected antigelling agents and allosteric modifiers

    Energy Technology Data Exchange (ETDEWEB)

    Mehanna, A.S.; Abraham, D.J. (Virginia Commonwealth Univ., Richmond (USA))

    1990-04-24

    This paper details comprehensive binding studies (solution and X-ray) of human hemoglobin A with a group of halogenated carboxylic acids that were investigated as potential antisickling agents. It is, to our knowledge, the first study to compare solution and crystal binding for a series of compounds under similar high-salt conditions used for cocrystallization. The compounds include ((3,4-dichlorobenzyl)oxy)acetic acid, ((p-bromobenzyl)oxy)acetic acid, clofibric acid, and bezafibrate. The location and stereochemistry of binding sites have been established by X-ray crystallography, while the number of binding sites and affinity constants were measured by using equilibrium dialysis. The observed crystal structures are consistent with the binding observed in solution and that the number of binding sites is independent of salt concentration, while the binding constant increases with increasing salt concentration. The studies also reveal that relatively small changes in the chemical structure of a drug molecule can result in entirely different binding sites on the protein. Moreover, the X-ray studies provide a possible explanation for the multiplicity in function exhibited by these compounds as allosteric modulators and/or antisickling agents. Finally, the studies indicate that these compounds bind differently to the R and T states of hemoglobin, and observation of special significance to the original design of these agents.

  19. The Metabotropic Glutamate Receptor 4 Positive Allosteric Modulator ADX88178 Inhibits Inflammatory Responses in Primary Microglia.

    Science.gov (United States)

    Ponnazhagan, Ranjani; Harms, Ashley S; Thome, Aaron D; Jurkuvenaite, Asta; Gogliotti, Rocco; Niswender, Colleen M; Conn, P Jeffrey; Standaert, David G

    2016-06-01

    While the specific trigger of Parkinson Disease (PD) in most patients is unknown, considerable evidence suggests that the neuroinflammatory response makes an essential contribution to the neurodegenerative process. Drugs targeting metabotropic glutamate receptors (mGlu receptors), 7 Transmembrane (7TM) spanning/G protein coupled receptors that bind glutamate, are emerging as therapeutic targets for PD and may have anti-inflammatory properties. ADX88178 is novel potent, selective, and brain-penetrant positive allosteric modulator of the mGlu4 which is under evaluation for treatment of PD and other neurological disorders. We used microglia cultured from mouse brain to determine if ADX88178 had direct effects on the inflammatory responses of these cells. We studied both microglia from wild type and Grm4 knock out mice. We found that activation of mGlu4 with ADX88178 attenuated LPS-induced inflammation in primary microglia, leading to a decrease in the expression of TNFα, MHCII, and iNOS, markers of pro-inflammatory responses. These effects were absent in microglia from mice lacking mGlu4. These results demonstrate a cell-autonomous anti-inflammatory effect of ADX88178 mediated mGlu4 activation on microglia, and suggest that this drug or similar activators or potentiators of mGlu4 may have disease-modifying as well as symptomatic effects in PD and other brain disorders with an inflammatory component. PMID:26872456

  20. Optimization of allosteric MEK inhibitors. Part 2: Taming the sulfamide group balances compound distribution properties.

    Science.gov (United States)

    Hartung, Ingo V; Hammer, Stefanie; Hitchcock, Marion; Neuhaus, Roland; Scholz, Arne; Siemeister, Gerhard; Bohlmann, Rolf; Hillig, Roman C; Pühler, Florian

    2016-01-01

    Recently, we had identified an unexplored pocket adjacent to the known binding site of allosteric MEK inhibitors which allowed us to design highly potent and in vivo efficacious novel inhibitors. We now report that our initial preclinical candidate, featuring a phenoxy side chain with a sulfamide capping group, displayed human carbonic anhydrase off-target activity and species-dependent blood cell accumulation, which prevented us from advancing this candidate further. Since this sulfamide MEK inhibitor displayed an exceptionally favorable PK profile with low brain penetration potential despite being highly oral bioavailable, we elected to keep the sulfamide capping group intact while taming its unwanted off-target activity by optimizing the structural surroundings. Introduction of a neighboring fluorine atom or installation of a methylene linker reduced hCA potency sufficiently, at the cost of MEK target potency. Switching to a higher fluorinated central core reinstated high MEK potency, leading to two new preclinical candidates with long half-lives, high bioavailabilities, low brain penetration potential and convincing efficacy in a K-Ras-mutated A549 xenograft model. PMID:26611920

  1. CRISIS COMMUNICATION IN UNIVERSITIES

    Directory of Open Access Journals (Sweden)

    Canan MADRAN

    2015-07-01

    Full Text Available Abstract Institutions should implement effective crisis communication strategies to manage their reputations in crisis situations. Thus, the negative perceptions that may occur because of crisis can be reduced and eliminated by continuously informing stakeholders. Therefore, various researches are needed in the area of crisis communication management. The aim of the study is to determine the types of crises that often occur in universities and evaluate the crisis communication efforts in higher education institutions. Crises and crisis communication efforts were evaluated within the framework of media reflections in this study. Content analysis was applied in the classification of crises and responses provided for crises. As a result, the types of crises in Turkish universities were determined as campus safety, actions, protests, loss of confidential information, loss of financial opportunities, loss of key managers and personnel, staff problems, increase of accidents, slander and gossip, unnecessary explanations, rumors, damage to organization and employee reputation, terrorism, workplace violence, corruption, fire and epidemic. It is seen that universities don’t make any communicational effort regarding campus safety, staff problems, increase of accidents, corruption or fire.

  2. Virtual Communication - Modern Business Communication

    OpenAIRE

    Grigorescu Adriana; Lupu Maria-Magdalena

    2014-01-01

    Along with the appearance of the informational technology, social networks and online shops, communication has received a new meaning, a new aspect and a new set of rules. It seems that the act of communication has completely moved on the internet. On-line is a very dynamic domain, new for everybody and with a lot of opportunities to exploit, an environment that offers interactive communication with instant feedback from the consumers when they shop on line. Such knowledge is essential in the...

  3. Effective communication

    International Nuclear Information System (INIS)

    At the Waste Isolation Pilot Plant (WIPP) the responsibilities assigned to public affairs (PA) include communications to two main groups: institutional representatives and the general public. Research data indicates that these two populations perceive risk in different fashions. This paper discusses these distinct perceptions and how the communication programs at WIPP have been designed to accommodate these two differences

  4. Communication Notebook.

    Science.gov (United States)

    Bachman, Duane

    A wide variety of internal and external communication methods used by the Piqua City School District (Ohio) are described. A philosophy statement is followed by descriptions of the roles of the board of education, the community, the teachers, the superintendent, and the media in an effective communications program. Among the 41 external…

  5. Communicator, 1997.

    Science.gov (United States)

    Bortolussi, Vicki, Ed.

    1997-01-01

    The CAG "Communicator" focus is on serving gifted students in California. This document consists of the four issues of "communicator" issued during 1997. Featured articles include: (1) "The Gifted Student At Risk. It Can't Be True" (Judy Roseberry); (2) "Tech Net-Technology and At-Risk Students" (Judy Lieb); (3) "Reviving Ophelia: Saving the…

  6. Organizacional Communication: Theoretical Matrices And Communicative Approaches

    Directory of Open Access Journals (Sweden)

    Msc. Hilda Saladrigas Medina

    2005-01-01

    Full Text Available The organizacional communication is a young discipline that has its conceptual and theoretical matrices in Social Psychology, the Sociology and the Management sciences, for that reason has been explained through diverse psychological , sistémicos, contingenciales, interpretativos and critical approaches between which the mechanics can be mentioned. The postulates of these can be analyzed to the light of the three positions that exist around the construction of the knowledge, that is the analytical positions empirical, the interpretativas and the critics. It explains theoretical and methodologic, explicit and implicit the influences. These budgets have barely been associate to the conceptual bodies that have studied the massive communication in spite of having coincident points. At the moment new tendencies in their study and interpretation, as well as its presence are appraised in which it has occurred in calling field of the Social Communication, that is in the curricula which they form the social signallers, in the lines of investigation which they develop to faculties of social communication and compatible research centers to these thematic ones, in the specialized bibliography and events.

  7. Phonetic Recalibration Only Occurs in Speech Mode

    Science.gov (United States)

    Vroomen, Jean; Baart, Martijn

    2009-01-01

    Upon hearing an ambiguous speech sound dubbed onto lipread speech, listeners adjust their phonetic categories in accordance with the lipread information (recalibration) that tells what the phoneme should be. Here we used sine wave speech (SWS) to show that this tuning effect occurs if the SWS sounds are perceived as speech, but not if the sounds…

  8. A naturally occurring trap for antiprotons

    International Nuclear Information System (INIS)

    The phenomenon of delayed annihilation of antiprotons in helium is the first instance of a naturally occurring trap for antimatter in ordinary matter. Recent studies of this effect at CERN are summarized, and plans are described for laser excitation experiments to test its interpretation in terms of metastable exotic helium atom formation. (author)

  9. Intercultural Communication

    Directory of Open Access Journals (Sweden)

    Georgeta Modiga

    2014-05-01

    Full Text Available The concept of culture has become one of strategic importance for all disciplines studying human and social universe, being invested today with multiple explanatory connotations. Meanwhile, conjunction and theoretical approaches we witness interference, under the imperative of interdisciplinary vision lead us, often up to a damaging confusion between communication and culture. Distinction between symbolic and instrumental, of culture and civilization are necessary to not confuse the contents of symbolic culture media of communication technology. An inventory of issues and social transformations that have acquired an indisputable relevance in contemporary development equation surgery is necessary but difficult. It should be mentioned two of them, given their global significance: the rediscovery of culture as a defining factor of the social and importance that have acquired communication processes in living societies. In fact, between the two aspects there is a relationship of inherent and consubstantiality, validated by actual historical experience. Culture and Communication is now a binomial with terms interchangeably, the two processes intertwined in a single block. Welding of the two dimensions was otherwise devoted to the vocabulary of social sciences and humanities through the concepts of culture media and intercultural communication. If we examine the paradigm shift in the theoretical space of the last century, the most surprising phenomena that we observe is that theories concerning communication space literally invaded the area that was traditionally reserved for theories about culture. For theorists today, communication is a structural constituent and all definitions, descriptions and characterizations that build on contemporary culture.

  10. Communicating EAM

    DEFF Research Database (Denmark)

    Groth, Sanne Krogh

    Since the early years of electro acoustic music great self-awareness is found among the field’s composers who often and willingly have communicated historical chronology, thoughts about analysis, aesthetic directions and rivalries. This we find both in relation to the historical studios (Schaeffe......Since the early years of electro acoustic music great self-awareness is found among the field’s composers who often and willingly have communicated historical chronology, thoughts about analysis, aesthetic directions and rivalries. This we find both in relation to the historical studios......’s communication of EAM and Sound Art....

  11. Wireless Communications

    Science.gov (United States)

    1991-01-01

    A technology utilization project led to the commercial adaptation of a Space Shuttle Orbiter wireless infrared voice communications system. The technology was adapted to a LAN system by Wilton Industries, one of the participants. Because the system is cable-free, installation charges are saved, and it can be used where cable is impractical. Resultant products include the IRplex 6000. Transceivers can be located anywhere and can include mobile receivers. The system provides wireless LAN coverage up to 44,000 square feet. applications include stock exchange communications, trade shows, emergency communications, etc.

  12. Satellite Communications

    CERN Document Server

    Pelton, Joseph N

    2012-01-01

    The field of satellite communications represents the world's largest space industry. Those who are interested in space need to understand the fundamentals of satellite communications, its technology, operation, business, economic, and regulatory aspects. This book explains all this along with key insights into the field's future growth trends and current strategic challenges. Fundamentals of Satellite Communications is a concise book that gives all of the key facts and figures as well as a strategic view of where this dynamic industry is going. Author Joseph N. Pelton, PhD, former Dean of the International Space University and former Director of Strategic Policy at Intelstat, presents a r

  13. Spin exchange monitoring of the strong positive homotropic allosteric binding of a tetraradical by a synthetic receptor in water.

    Science.gov (United States)

    Bardelang, David; Casano, Gilles; Poulhès, Florent; Karoui, Hakim; Filippini, Jessica; Rockenbauer, Antal; Rosas, Roselyne; Monnier, Valérie; Siri, Didier; Gaudel-Siri, Anouk; Ouari, Olivier; Tordo, Paul

    2014-12-17

    The flexible tetranitroxide 4T has been prepared and was shown to exhibit a nine line EPR spectrum in water, characteristic of significant through space spin exchange (J(ij)) between four electron spins interacting with four nitrogen nuclei (J(ij) ≫ a(N)). Addition of CB[8] to 4T decreases dramatically all the Jij couplings, and the nine line spectrum is replaced by the characteristic three line spectrum of a mononitroxide. The supramolecular association between 4T and CB[8] involves a highly cooperative asymmetric complexation by two CB[8] (K1 = 4027 M(-1); K2 = 202,800 M(-1); α = 201) leading to a rigid complex with remote nitroxide moieties. The remarkable enhancement for the affinity of the second CB[8] corresponds to an allosteric interaction energy of ≈13 kJ mol(-1), which is comparable to that of the binding of oxygen by hemoglobin. These results are confirmed by competition and reduction experiments, DFT and molecular dynamics calculations, mass spectrometry, and liquid state NMR of the corresponding reduced complex bearing hydroxylamine moieties. This study shows that suitably designed molecules can generate allosteric complexation with CB[8]. The molecule must (i) carry several recognizable groups for CB[8] and (ii) be folded so that the first binding event reorganizes the molecule (unfold) for a better subsequent recognition. The presence of accessible protonable amines and H-bond donors to fit with the second point are also further stabilizing groups of CB[8] complexation. In these conditions, the spin exchange coupling between four radicals has been efficiently and finely tuned and the resulting allosteric complexation induced a dramatic stabilization enhancement of the included paramagnetic moieties in highly reducing conditions through the formation of the supramolecular 4T@CB[8]2 complex. PMID:25418528

  14. Positive allosteric modulation of mGluR5 accelerates extinction learning but not relearning following methamphetamine self-administration

    Directory of Open Access Journals (Sweden)

    Peter R Kufahl

    2012-11-01

    Full Text Available Recent studies have implicated glutamate neurotransmission as an important substrate for the extinction of conditioned behaviors, including responding for drug reinforcement. Positive allosteric modulation of the type-5 metabotropic glutamate receptor (mGluR5 in particular has emerged as a treatment strategy for the enhancement of extinction of drug-motivated behaviors. Here, we investigated the effects of the mGluR5 positive allosteric modulator CDPPB, a compound known for its cognitive enhancing effects in rodents, on extinction learning in rats with different histories of methamphetamine (METH training. Rats were trained to self-administer METH under two conditions: 16 daily sessions of short access (90 min/day, ShA, or 8 daily sessions of short access followed by 8 sessions of long access (6 hr/day, LgA. Control rats self-administered sucrose pellets in daily 30 min sessions. Next, rats were administered vehicle or 30 mg/kg CDPPB prior to 7 consecutive daily extinction sessions, subjected to additional extinction sessions to re-establish a post-treatment baseline, and then tested for reinstatement of behavior in the presence of METH- or sucrose-paired cues. Rats were then subjected to a second series of extinction sessions, preceded by vehicle or 30 mg/kg CDPPB, and an additional test for cue-triggered reinstatement. CDPPB treatment resulted in a more rapid extinction of responding on the active lever, especially in the early sessions of the first extinction sequence. However, treatment effects were minimal during subsequent cue reinstatement tests and nonexistent during the second series of extinction sessions. Rats with histories of ShA, LgA and sucrose training expressed similar behavioral sensitivities to CDPPB, with LgA rats demonstrating a modestly higher treatment effect. Positive allosteric modulation of mGluR5 may therefore have some beneficial effects on efforts to facilitate extinction learning and reduce methamphetamine seeking.

  15. Positive Allosteric Modulator of GABA Lowers BOLD Responses in the Cingulate Cortex.

    Directory of Open Access Journals (Sweden)

    Susanna A Walter

    Full Text Available Knowledge about the neural underpinnings of the negative blood oxygen level dependent (BOLD responses in functional magnetic resonance imaging (fMRI is still limited. We hypothesized that pharmacological GABAergic modulation attenuates BOLD responses, and that blood concentrations of a positive allosteric modulator of GABA correlate inversely with BOLD responses in the cingulate cortex. We investigated whether or not pure task-related negative BOLD responses were co-localized with pharmacologically modulated BOLD responses. Twenty healthy adults received either 5 mg diazepam or placebo in a double blind, randomized design. During fMRI the subjects performed a working memory task. Results showed that BOLD responses in the cingulate cortex were inversely correlated with diazepam blood concentrations; that is, the higher the blood diazepam concentration, the lower the BOLD response. This inverse correlation was most pronounced in the pregenual anterior cingulate cortex and the anterior mid-cingulate cortex. For subjects with diazepam plasma concentration > 0.1 mg/L we observed negative BOLD responses with respect to fixation baseline. There was minor overlap between cingulate regions with task-related negative BOLD responses and regions where the BOLD responses were inversely correlated with diazepam concentration. We interpret that the inverse correlation between the BOLD response and diazepam was caused by GABA-related neural inhibition. Thus, this study supports the hypothesis that GABA attenuates BOLD responses in fMRI. The minimal overlap between task-related negative BOLD responses and responses attenuated by diazepam suggests that these responses might be caused by different mechanisms.

  16. Presence of a putative steroidal allosteric site on glycoprotein hormone receptors.

    Science.gov (United States)

    Rossi, Mario; Dimida, Antonio; Ferrarini, Eleonora; Silvano, Elena; De Marco, Giuseppina; Agretti, Patrizia; Aloisi, Gabriella; Simoncini, Tommaso; Di Bari, Lorenzo; Tonacchera, Massimo; Giorgi, Franco; Maggio, Roberto

    2009-11-25

    In a previous work we found that the insecticide 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT), inhibits the accumulation of cAMP as induced by the bovine thyroid stimulating hormone (bTSH) in cells transfected with the TSH receptor. In this work, we demonstrate that the DDT molecular analogues, diethylstilbestrol and quercetine, are more potent inhibitors of the TSH receptor activity than DDT itself. The notion that all these compounds interfere with nuclear estrogen receptors, as either agonists (DDT and diethylstilbestrol) or antagonists (quercetin), prompted us to test the ability of the steroid hormone 17-beta-estradiol to inhibit the TSH receptor activity. We found that estrogen exposure causes a modest but significant inhibition of the bTSH induced cAMP accumulation both in transfected CHO-TSH receptor and Fischer Rat Thyroid Low Serum 5% (FRTL-5) cells. When applied to CHO cells transfected with the luteinizing hormone receptor, 17-beta-estradiol proved capable of inhibiting the hCG induced cAMP accumulation at a concentration as low as 10nM, though the effect was not greater than 35%. The effect of 17-beta-estradiol was not estrogen receptors mediated, as co-transfection of the estrogen receptor alpha and beta subunits with LH receptor caused cAMP to increase above the level attained by the sole hCG stimulation, and not to decrease it as expected. These data suggest the presence of a steroidal-like allosteric binding site on glycoprotein hormone receptors. PMID:19766106

  17. Role of connecting loop I in catalysis and allosteric regulation of human glucokinase.

    Science.gov (United States)

    Martinez, Juliana A; Larion, Mioara; Conejo, Maria S; Porter, Carol M; Miller, Brian G

    2014-07-01

    Glucokinase (GCK, hexokinase IV) is a monomeric enzyme with a single glucose binding site that displays steady-state kinetic cooperativity, a functional characteristic that affords allosteric regulation of GCK activity. Structural evidence suggests that connecting loop I, comprised of residues 47-71, facilitates cooperativity by dictating the rate and scope of motions between the large and small domains of GCK. Here we investigate the impact of varying the length and amino acid sequence of connecting loop I upon GCK cooperativity. We find that sequential, single amino acid deletions from the C-terminus of connecting loop I cause systematic decreases in cooperativity. Deleting up to two loop residues leaves the kcat value unchanged; however, removing three or more residues reduces kcat by 1000-fold. In contrast, the glucose K0.5 and KD values are unaffected by shortening the connecting loop by up to six residues. Substituting alanine or glycine for proline-66, which adopts a cis conformation in some GCK crystal structures, does not alter cooperativity, indicating that cis/trans isomerization of this loop residue does not govern slow conformational reorganizations linked to hysteresis. Replacing connecting loop I with the corresponding loop sequence from the catalytic domain of the noncooperative isozyme human hexokinase I (HK-I) eliminates cooperativity without impacting the kcat and glucose K0.5 values. Our results indicate that catalytic turnover requires a minimal length of connecting loop I, whereas the loop has little impact upon the binding affinity of GCK for glucose. We propose a model in which the primary structure of connecting loop I affects cooperativity by influencing conformational dynamics, without altering the equilibrium distribution of GCK conformations. PMID:24723372

  18. Negative Allosteric Modulators of Metabotropic Glutamate Receptors Subtype 5 in Addiction: a Therapeutic Window

    Science.gov (United States)

    2016-01-01

    Background: Abundant evidence at the anatomical, electrophysiological, and molecular levels implicates metabotropic glutamate receptor subtype 5 (mGluR5) in addiction. Consistently, the effects of a wide range of doses of different mGluR5 negative allosteric modulators (NAMs) have been tested in various animal models of addiction. Here, these studies were subjected to a systematic review to find out if mGluR5 NAMs have a therapeutic potential that can be translated to the clinic. Methods: Literature on consumption/self-administration and reinstatement of drug seeking as outcomes of interest published up to April 2015 was retrieved via PubMed. The review focused on the effects of systemic (i.p., i.v., s.c.) administration of the mGluR5 NAMs 3-((2-Methyl-4-thiazolyl)ethynyl)pyridine (MTEP) and 2-Methyl-6-(phenylethynyl)pyridine (MPEP) on paradigms with cocaine, ethanol, nicotine, and food in rats. Results: MTEP and MPEP were found to reduce self-administration of cocaine, ethanol, and nicotine at doses ≥1mg/kg and 2.5mg/kg, respectively. Dose-response relationship resembled a sigmoidal curve, with low doses not reaching statistical significance and high doses reliably inhibiting self-administration of drugs of abuse. Importantly, self-administration of cocaine, ethanol, and nicotine, but not food, was reduced by MTEP and MPEP in the dose range of 1 to 2mg/kg and 2.5 to 3.2mg/kg, respectively. This dose range corresponds to approximately 50% to 80% mGluR5 occupancy. Interestingly, the limited data found in mice and monkeys showed a similar therapeutic window. Conclusion: Altogether, this review suggests a therapeutic window for mGluR5 NAMs that can be translated to the treatment of substance-related and addictive disorders. PMID:26802568

  19. A potential yeast actin allosteric conduit dependent on hydrophobic core residues val-76 and trp-79.

    Science.gov (United States)

    Wen, Kuo-Kuang; McKane, Melissa; Stokasimov, Ema; Fields, Jonathon; Rubenstein, Peter A

    2010-07-01

    Intramolecular allosteric interactions responsible for actin conformational regulation are largely unknown. Previous work demonstrated that replacing yeast actin Val-76 with muscle actin Ile caused decreased nucleotide exchange. Residue 76 abuts Trp-79 in a six-residue linear array beginning with Lys-118 on the surface and ending with His-73 in the nucleotide cleft. To test if altering the degree of packing of these two residues would affect actin dynamics, we constructed V76I, W79F, and W79Y single mutants as well as the Ile-76/Phe-79 and Ile-76/Tyr-79 double mutants. Tyr or Phe should decrease crowding and increase protein flexibility. Subsequent introduction of Ile should restore packing and dampen changes. All mutants showed decreased growth in liquid medium. W79Y alone was severely osmosensitive and exhibited vacuole abnormalities. Both properties were rescued by Ile-76. Phe-79 or Tyr decreased the thermostability of actin and increased its nucleotide exchange rate. These effects, generally greater for Tyr than for Phe, were reversed by introduction of Ile-76. HD exchange showed that the mutations caused propagated conformational changes to all four subdomains. Based on results from phosphate release and light-scattering assays, single mutations affected polymerization in the order of Ile, Phe, and Tyr from least to most. Introduction of Ile-76 partially rescued the polymerization defects caused by either Tyr-79 or Phe-79. Thus, alterations in crowding of the 76-79 residue pair can strongly affect actin conformation and behavior, and these results support the theory that the amino acid array in which they are located may play a central role in actin regulation. PMID:20442407

  20. Identifying allosteric fluctuation transitions between different protein conformational states as applied to Cyclin Dependent Kinase 2

    Directory of Open Access Journals (Sweden)

    Gu Jenny

    2007-02-01

    Full Text Available Abstract Background The mechanisms underlying protein function and associated conformational change are dominated by a series of local entropy fluctuations affecting the global structure yet are mediated by only a few key residues. Transitional Dynamic Analysis (TDA is a new method to detect these changes in local protein flexibility between different conformations arising from, for example, ligand binding. Additionally, Positional Impact Vertex for Entropy Transfer (PIVET uses TDA to identify important residue contact changes that have a large impact on global fluctuation. We demonstrate the utility of these methods for Cyclin-dependent kinase 2 (CDK2, a system with crystal structures of this protein in multiple functionally relevant conformations and experimental data revealing the importance of local fluctuation changes for protein function. Results TDA and PIVET successfully identified select residues that are responsible for conformation specific regional fluctuation in the activation cycle of Cyclin Dependent Kinase 2 (CDK2. The detected local changes in protein flexibility have been experimentally confirmed to be essential for the regulation and function of the kinase. The methodologies also highlighted possible errors in previous molecular dynamic simulations that need to be resolved in order to understand this key player in cell cycle regulation. Finally, the use of entropy compensation as a possible allosteric mechanism for protein function is reported for CDK2. Conclusion The methodologies embodied in TDA and PIVET provide a quick approach to identify local fluctuation change important for protein function and residue contacts that contributes to these changes. Further, these approaches can be used to check for possible errors in protein dynamic simulations and have the potential to facilitate a better understanding of the contribution of entropy to protein allostery and function.

  1. Adaptive response and genomic instability: allosteric response of genome to negative impact

    International Nuclear Information System (INIS)

    Currently, there is an upsurge concern on the unique response of living cells to low dose ionizing radiation for its inconformity to the existing paradigm of the biological action of radiation and its impact on the current understanding of risk evaluation of health effect of radiation in our workplace and environment. For the allosteric response to have significance, the cells must have an excellent sensing mechanism to discriminate tolerable and intolerable signals. In a series of experiments with mammalian, including human, cells, we demonstrated a novel sensing and signaling mechanism in the low-dose irradiated cells that was mediated by a PKCα-p3BMAPK-PLCδ1 feedback regulatory loop. Upon irradiation, PKCα is immediately activated, which in turn activate p38MAPK. The activation of p38MAPK is feedbacked to the activation of PKCα via PLCδ1, which catalyzes the hydrolysis of PtdInsP2 to generate PKCα-directed second messengers DAG and lnsP3. At low doses, the PKCα and p38MAPK continue to be activated for long time through this feedback loop, but when the cells encounter the high dose (>10 cGy or equivalent), the feedback loop is immediately comes to shutdown by deprivation of PKCα protein, known as down-regulation of PKC signaling. Thus, PKCα plays a key role in the long lasting nature of adaptive response to low doses and a binary switch to the genomic instability by too much signals. Tumor suppressor protein, p53, is a downstream effecter

  2. Natural occurring radioactive substances. Vol. 1

    International Nuclear Information System (INIS)

    Naturally occurring radioactive substances produced by cosmic rays of those of terrestrial origin are surveyed. The different radioactive decay series are discussed. Special emphasis is given to the element radium as regards its properties and distribution in different environmental samples. The properties of naturally occurring k-40 and its distribution in different natural media are also outlined. Induced radionuclides which are formed as a result of the interaction of cosmic rays with the constituents of the atmosphere are mentioned. In this respect the intensity of natural background radiation and the dose at different locations and levels is surveyed. Some regions of exceptionally high radioactivity which result in high exposure rates are mentioned. Monazite deposits and water springs are mentioned in some detail. The Oklo phenomenon as a natural reactor is also discussed. 8 tabs

  3. Naturally occurring radionuclides and Earth sciences

    OpenAIRE

    G. Ferrara

    1997-01-01

    Naturally occurring radionuclides are used in Earth sciences for two fundamental purposes: age determination of rocks and minerals and studies of variation of the isotopic composition of radiogenic nuclides. The methodologies that are in use today allow us to determine ages spanning from the Earth's age to the late Quaternary. The variations of isotopic composition of radiogenic nuclides can be applied to problems of mantle evolution, magma genesis and characterization with respect to differe...

  4. Transient global amnesia occurring as migraine aura

    OpenAIRE

    Montagna, Pasquale; Cerullo, Angelina; Cortelli, Pietero

    2000-01-01

    We describe a case of transient global amnesia (TGA) occurring as migraine aura. TGA prevalence is higher among migraineurs and has been ascribed to spreading depression in the hippocampus. Our patient, a 38-year-old physician, developed migraine without aura in early adolescence and from age 20 years, had experienced rare attacks of migraine with aura,. At ages 36 and 38 years, he suffered two attacks of sudden-onset anterograde amnesia, which lasted 5 hours and were immediately followed by ...

  5. Naturally Occuring Fish Poisons from Plants

    Science.gov (United States)

    Cannon, Jonathan G.; Burton, Robert A.; Wood, Steven G.; Owen, Noel L.

    2004-10-01

    Since prehistoric times, cultures throughout the world have used piscicidal (fish poisoning) plants for fishing. In recent times, scientists have identified many of the plant compounds responsible for killing the fish and have found that these compounds possess other important biological properties, such as insecticidal and anti-cancer activities. This article reviews some of the chemical research that has been performed on naturally occurring fish poisons, including plant sources, methods of use, toxicity, and mechanisms of action of piscicides.

  6. Positive allosteric modulation of GABA-A receptors reduces capsaicin-induced primary and secondary hypersensitivity in rats

    DEFF Research Database (Denmark)

    Hansen, Rikke Rie; Erichsen, Helle K; Brown, David T;

    2012-01-01

    GABA-A receptor positive allosteric modulators (PAMs) mediate robust analgesia in animal models of pathological pain, in part via enhancing injury-induced loss of GABA-A-α2 and -α3 receptor function within the spinal cord. As yet, a lack of clinically suitable tool compounds has prevented this...... concept being tested in humans. Prior to assessing the efficacy of GABA-A receptor PAMs in a human volunteer pain model we have compared compounds capable of variously modulating GABA-A receptor function in comparable rat models of capsaicin-induced acute nocifensive flinching behaviour and secondary...

  7. Contrasting Effects of Allosteric and Orthosteric Agonists on M1 Muscarinic Acetylcholine Receptor Internalization and Down-regulation

    OpenAIRE

    Thomas, Rachel L.; Christopher J Langmead; Wood, Martyn D; Challiss, R.A. John

    2009-01-01

    A new class of subtype-selective muscarinic acetylcholine (mACh) receptor agonist that activates the receptor through interaction at a site distinct from the orthosteric acetylcholine binding site has been reported recently. Here, we have compared the effects of orthosteric (oxotremorine-M, arecoline, pilocarpine) and allosteric [4-n-butyl-1-[4-(2-methylphenyl)-4-oxo-1-butyl] piperidine (AC-42); 1-[3-(4-butyl-1-piperidinyl)propyl]-3,4-dihydro-2(1H)-quinolinone (77-LH-28-1)] agonists on M1 mAC...

  8. Molecular modeling study on the allosteric inhibition mechanism of HIV-1 integrase by LEDGF/p75 binding site inhibitors.

    Directory of Open Access Journals (Sweden)

    Weiwei Xue

    Full Text Available HIV-1 integrase (IN is essential for the integration of viral DNA into the host genome and an attractive therapeutic target for developing antiretroviral inhibitors. LEDGINs are a class of allosteric inhibitors targeting LEDGF/p75 binding site of HIV-1 IN. Yet, the detailed binding mode and allosteric inhibition mechanism of LEDGINs to HIV-1 IN is only partially understood, which hinders the structure-based design of more potent anti-HIV agents. A molecular modeling study combining molecular docking, molecular dynamics simulation, and binding free energy calculation were performed to investigate the interaction details of HIV-1 IN catalytic core domain (CCD with two recently discovered LEDGINs BI-1001 and CX14442, as well as the LEDGF/p75 protein. Simulation results demonstrated the hydrophobic domain of BI-1001 and CX14442 engages one subunit of HIV-1 IN CCD dimer through hydrophobic interactions, and the hydrophilic group forms hydrogen bonds with HIV-1 IN CCD residues from other subunit. CX14442 has a larger tert-butyl group than the methyl of BI-1001, and forms better interactions with the highly hydrophobic binding pocket of HIV-1 IN CCD dimer interface, which can explain the stronger affinity of CX14442 than BI-1001. Analysis of the binding mode of LEDGF/p75 with HIV-1 IN CCD reveals that the LEDGF/p75 integrase binding domain residues Ile365, Asp366, Phe406 and Val408 have significant contributions to the binding of the LEDGF/p75 to HIV1-IN. Remarkably, we found that binding of BI-1001 and CX14442 to HIV-1 IN CCD induced the structural rearrangements of the 140 s loop and oration displacements of the side chains of the three conserved catalytic residues Asp64, Asp116, and Glu152 located at the active site. These results we obtained will be valuable not only for understanding the allosteric inhibition mechanism of LEDGINs but also for the rational design of allosteric inhibitors of HIV-1 IN targeting LEDGF/p75 binding site.

  9. Identification of an Allosteric Pocket on Human Hsp70 Reveals a Mode of Inhibition of This Therapeutically Important Protein

    OpenAIRE

    Rodina, Anna; Patel, Pallav D.; Kang, Yanlong; Patel, Yogita; Baaklini, Imad; Wong, Michael J. H.; Taldone, Tony; Yan, Pengrong; Yang, Chenghua; Maharaj, Ronnie; Gozman, Alexander; Patel, Maulik R.; Patel, Hardik J.; Chirico, William; Erdjument-Bromage, Hediye

    2013-01-01

    Hsp70s are important cancer chaperones that act upstream of Hsp90 and exhibit independent anti-apoptotic activities. To develop chemical tools for the study of human Hsp70, we developed a homology model that unveils a previously unknown allosteric site located in the nucleotide binding domain of Hsp70. Combining structure-based design and phenotypic testing, we discovered a previously unknown inhibitor of this site, YK5. In cancer cells, this compound is a potent and selective binder of the c...

  10. Multiple Transmembrane Binding Sites for p-Trifluoromethyldiazirinyl-etomidate, a Photoreactive Torpedo Nicotinic Acetylcholine Receptor Allosteric Inhibitor*

    OpenAIRE

    Hamouda, Ayman K.; Stewart, Deirdre S.; Husain, S. Shaukat; Cohen, Jonathan B.

    2011-01-01

    Photoreactive derivatives of the general anesthetic etomidate have been developed to identify their binding sites in γ-aminobutyric acid, type A and nicotinic acetylcholine receptors. One such drug, [3H]TDBzl-etomidate (4-[3-(trifluoromethyl)-3H-diazirin-3-yl]benzyl-[3H]1-(1-phenylethyl)-1H-imidazole-5-carboxylate), acts as a positive allosteric potentiator of Torpedo nACh receptor (nAChR) and binds to a novel site in the transmembrane domain at the γ-α subunit interface. To extend our unders...

  11. A novel strategy for selection of allosteric ribozymes yields RiboReporter™ sensors for caffeine and aspartame

    OpenAIRE

    Ferguson, Alicia; Boomer, Ryan M.; Kurz, Markus; Keene, Sara C.; Diener, John L.; Keefe, Anthony D.; Wilson, Charles; Cload, Sharon T.

    2004-01-01

    We have utilized in vitro selection technology to develop allosteric ribozyme sensors that are specific for the small molecule analytes caffeine or aspartame. Caffeine- or aspartame-responsive ribozymes were converted into fluorescence-based RiboReporter™ sensor systems that were able to detect caffeine or aspartame in solution over a concentration range from 0.5 to 5 mM. With read-times as short as 5 min, these caffeine- or aspartame-dependent ribozymes function as highly specific and facile...

  12. Benzothiazole Derivative as a Novel Mycobacterium tuberculosis Shikimate Kinase Inhibitor: Identification and Elucidation of Its Allosteric Mode of Inhibition.

    Science.gov (United States)

    Mehra, Rukmankesh; Rajput, Vikrant Singh; Gupta, Monika; Chib, Reena; Kumar, Amit; Wazir, Priya; Khan, Inshad Ali; Nargotra, Amit

    2016-05-23

    Mycobacterium tuberculosis shikimate kinase (Mtb-SK) is a key enzyme involved in the biosynthesis of aromatic amino acids through the shikimate pathway. Since it is proven to be essential for the survival of the microbe and is absent from mammals, it is a promising target for anti-TB drug discovery. In this study, a combined approach of in silico similarity search and pharmacophore building using already reported inhibitors was used to screen a procured library of 20,000 compounds of the commercially available ChemBridge database. From the in silico screening, 15 hits were identified, and these hits were evaluated in vitro for Mtb-SK enzyme inhibition. Two compounds presented significant enzyme inhibition with IC50 values of 10.69 ± 0.9 and 46.22 ± 1.2 μM. The best hit was then evaluated for the in vitro mode of inhibition where it came out to be an uncompetitive and noncompetitive inhibitor with respect to shikimate (SKM) and ATP, respectively, suggesting its binding at an allosteric site. Potential binding sites of Mtb-SK were identified which confirmed the presence of an allosteric binding pocket apart from the ATP and SKM binding sites. The docking simulations were performed at this pocket in order to find the mode of binding of the best hit in the presence of substrates and the products of the enzymatic reaction. Molecular dynamics (MD) simulations elucidated the probability of inhibitor binding at the allosteric site in the presence of ADP and shikimate-3-phosphate (S-3-P), that is, after the formation of products of the reaction. The inhibitor binding may prevent the release of the product from Mtb-SK, thereby inhibiting its activity. The binding stability and the key residue interactions of the inhibitor to this product complex were also revealed by the MD simulations. Residues ARG43, ILE45, and PHE57 were identified as crucial that were involved in interactions with the best hit. This is the first report of an allosteric binding site of Mtb-SK, which

  13. Information system support for business communication management

    OpenAIRE

    Grosek, Matjaž

    2013-01-01

    In the thesis we researched the field of communication in organizations. In the first part we described a case of communication and some problems that usually occur in the organizations, not using programs meant for communication. Later on we tested and described some of the already known solutions in the field of collaboration and communication. Then we presented the idea of the application that we realized in the following part of the thesis. The main part of the thesis is therefore meant f...

  14. PC communication

    International Nuclear Information System (INIS)

    This text book is comprised of five charters, which is about PC communication for beginners who need to learn manners and how to use Ketel and PC serve. So it introduces first, conception of PC and precautions on using PC communication, second, preparation for PC communication with Modem, its program, install, kinds of protocol and how to use protocol, third directions of emulator of PC communication and super session, fourth, instruction of Ketel with join and access, basic command of Ketel, list of Ketel's menu, Ketel editor, service guide, directions of News service, Stock and bond service business and economic figures, exchange rate and interest rate, tax culture and leisure, Ketel BBS service and posting. The last part has a instruction of PC-serve about join, basic command of PC-serve, service guide and practical guideline.

  15. Communication fail?

    Science.gov (United States)

    Jones, Matthew

    2016-06-01

    In response to Matin Durrani's editorial “Conference thoughts” (April p15), which bemoaned poor communication and limited social media use by physicists at the March meeting of the American Physical Society (APS).

  16. COMMUNICATIONS GROUP

    CERN Multimedia

    L. Taylor

    2011-01-01

    The CMS Communications Group, established at the start of 2010, has been busy in all three areas of its responsibility: (1) Communications Infrastructure, (2) Information Systems, and (3) Outreach and Education. Communications Infrastructure There are now 55 CMS Centres worldwide that are well used by physicists working on remote CMS shifts, Computing operations, data quality monitoring, data analysis and outreach. The CMS Centre@CERN in Meyrin, is the centre of the CMS offline and computing operations, hosting dedicated analysis efforts such as during the CMS Heavy Ion lead-lead running. With a majority of CMS sub-detectors now operating in a “shifterless” mode, many monitoring operations are now routinely performed from there, rather than in the main Control Room at P5. The CMS Communications Group, CERN IT and the EVO team are providing excellent videoconferencing support for the rapidly-increasing number of CMS meetings. In parallel, CERN IT and ...

  17. Marketing Communications

    OpenAIRE

    Rigerová, Lenka

    2013-01-01

    Marketing communications is the main theme of this dissertation. Aim of dissertation is to describe and to analysis marketing and also communication instruments of company Berger Huck, s.r.o. Output of practical part will be used for advertising campaign project. In the first part is processed of theoretical solutions. Technical literature is source of materials for this part of dissertation. In the theoretic parts is briefly described history and progress of marketing, main substance, d...

  18. Mapping Cannabinoid 1 Receptor Allosteric Site(s): Critical Molecular Determinant and Signaling Profile of GAT100, a Novel, Potent, and Irreversibly Binding Probe.

    Science.gov (United States)

    Laprairie, Robert B; Kulkarni, Abhijit R; Kulkarni, Pushkar M; Hurst, Dow P; Lynch, Diane; Reggio, Patricia H; Janero, David R; Pertwee, Roger G; Stevenson, Lesley A; Kelly, Melanie E M; Denovan-Wright, Eileen M; Thakur, Ganesh A

    2016-06-15

    One of the most abundant G-protein coupled receptors (GPCRs) in brain, the cannabinoid 1 receptor (CB1R), is a tractable therapeutic target for treating diverse psychobehavioral and somatic disorders. Adverse on-target effects associated with small-molecule CB1R orthosteric agonists and inverse agonists/antagonists have plagued their translational potential. Allosteric CB1R modulators offer a potentially safer modality through which CB1R signaling may be directed for therapeutic benefit. Rational design of candidate, druglike CB1R allosteric modulators requires greater understanding of the architecture of the CB1R allosteric endodomain(s) and the capacity of CB1R allosteric ligands to tune the receptor's information output. We have recently reported the synthesis of a focused library of rationally designed, covalent analogues of Org27569 and PSNCBAM-1, two prototypic CB1R negative allosteric modulators (NAMs). Among the novel, pharmacologically active CB1R NAMs reported, the isothiocyanate GAT100 emerged as the lead by virtue of its exceptional potency in the [(35)S]GTPγS and β-arrestin signaling assays and its ability to label CB1R as a covalent allosteric probe with significantly reduced inverse agonism in the [(35)S]GTPγS assay as compared to Org27569. We report here a comprehensive functional profiling of GAT100 across an array of important downstream cell-signaling pathways and analysis of its potential orthosteric probe-dependence and signaling bias. The results demonstrate that GAT100 is a NAM of the orthosteric CB1R agonist CP55,940 and the endocannabinoids 2-arachidonoylglycerol and anandamide for β-arrestin1 recruitment, PLCβ3 and ERK1/2 phosphorylation, cAMP accumulation, and CB1R internalization in HEK293A cells overexpressing CB1R and in Neuro2a and STHdh(Q7/Q7) cells endogenously expressing CB1R. Distinctively, GAT100 was a more potent and efficacious CB1R NAM than Org27569 and PSNCBAM-1 in all signaling assays and did not exhibit the inverse

  19. Pharmacological characterization and modeling of the binding sites of novel 1,3-bis(pyridinylethynyl)benzenes as metabotropic glutamate receptor 5-selective negative allosteric modulators

    DEFF Research Database (Denmark)

    Mølck, Christina; Harpsøe, Kasper; Gloriam, David E;

    2012-01-01

    Metabotropic glutamate receptor subtype 5 (mGluR5) is a potential drug target in neurological and psychiatric disorders, and subtype-selective allosteric modulators have attracted much attention as potential drug candidates. In this study, the binding sites of three novel 2-methyl-6-(phenylethynyl......)pyridine (MPEP)-derived negative allosteric modulators, 2-, 3-, and 4-BisPEB, have been characterized. 2-, 3-, and 4-BisPEB are 1,3-bis(pyridinylethynyl)-benzenes and differ only by the position of the nitrogen atoms in the pyridine rings. Despite their high structural similarity, 2-BisPEB [1,3-bis(pyridin-2...

  20. Structure of N-acetyl-L-glutamate synthase/kinase from Maricaulis maris with the allosteric inhibitor L-arginine bound

    OpenAIRE

    Zhao, Gengxiang; Haskins, Nantaporn; Jin, Zhongmin; Allewell, Norma M.; Tuchman, Mendel; Shi, Dashuang

    2013-01-01

    Maricaulis maris N-acetylglutamate synthase/kinase (mmNAGS/K) catalyzes the first two steps in L-arginine biosynthesis and has a high degree of sequence and structural homology to human N-acetylglutamate synthase, a regulator of the urea cycle. The synthase activity of both mmNAGS/K and human NAGS are regulated by L-arginine, although L-arginine is an allosteric inhibitor of mmNAGS/K, but an activator of human NAGS. To investigate the mechanism of allosteric inhibition of mmNAGS/K by L-argini...

  1. Aesthetic Communication

    DEFF Research Database (Denmark)

    Thyssen, Ole

    2012-01-01

    Based on Niklas Luhmann's systems theory, aesthetics is defined as a manner of reinforcing the connectivity, or Anschlusswert, of communication. Without changing the content, a message can be made more attractive, strengthening the receiver's willingness to be attentive and accepting. As communic......Based on Niklas Luhmann's systems theory, aesthetics is defined as a manner of reinforcing the connectivity, or Anschlusswert, of communication. Without changing the content, a message can be made more attractive, strengthening the receiver's willingness to be attentive and accepting....... As communication inevitably makes use of a sensuous medium, such as light or sound, all communication has an aesthetic dimension. In the 19th Century, an important distinction was made between pure and applied art, following Immanuel Kant's separation of theory of knowledge, moral theory and aesthetic theory....... Whereas pure art is produced in order to be observed, applied art has to fulfill practical purposes as well. Modern organizations, defined as systems of communication, may use art works to embellish and define themselves. But they inevitably use applied art as a practical tool in their normal...

  2. Naturally occurring anti M complicating ABO grouping

    Directory of Open Access Journals (Sweden)

    Safoorah Khalid

    2011-01-01

    Full Text Available Anti M is considered a naturally occurring antibody that is usually active at temperatures below 37°C and is thus of no clinical significance. This antibody, if present in an individual, can lead to a discrepancy between forward and reverse ABO grouping and thus creates diagnostic difficulties for blood bank staff. We report a case of a 58-year-old lady who had an unexpected reaction in reverse grouping due to anti M that posed a problem for us in the interpretation of results of her blood group. We also reviewed the literature to find out the significance of such discrepancy in blood grouping.

  3. Naturally occurring anti M complicating ABO grouping.

    Science.gov (United States)

    Khalid, Safoorah; Dantes, Roelyn; Varghese, Sunu; Al Hakawati, Imadeddin

    2011-01-01

    Anti M is considered a naturally occurring antibody that is usually active at temperatures below 37°C and is thus of no clinical significance. This antibody, if present in an individual, can lead to a discrepancy between forward and reverse ABO grouping and thus creates diagnostic difficulties for blood bank staff. We report a case of a 58-year-old lady who had an unexpected reaction in reverse grouping due to anti M that posed a problem for us in the interpretation of results of her blood group. We also reviewed the literature to find out the significance of such discrepancy in blood grouping. PMID:21393909

  4. Naturally occurring anti M complicating ABO grouping

    OpenAIRE

    Safoorah Khalid; Roelyn Dantes; Sunu Varghese; Imadeddin Al Hakawati

    2011-01-01

    Anti M is considered a naturally occurring antibody that is usually active at temperatures below 37°C and is thus of no clinical significance. This antibody, if present in an individual, can lead to a discrepancy between forward and reverse ABO grouping and thus creates diagnostic difficulties for blood bank staff. We report a case of a 58-year-old lady who had an unexpected reaction in reverse grouping due to anti M that posed a problem for us in the interpretation of results of her blood gr...

  5. Persulfate activation by naturally occurring trace minerals

    International Nuclear Information System (INIS)

    Highlights: ► Persulfate decomposition and activation by 13 trace minerals was investigated. ► Pyrite and cobaltite addition resulted in rapid persulfate decomposition. ► Pyrite promoted rapid generation of sulfate radical and hydroxyl radical. ► Most trace minerals did not decompose or activate persulfate. ► Some trace minerals inhibited persulfate decomposition and activation. - Abstract: The potential for 13 naturally occurring minerals to mediate the decomposition of persulfate and generate a range of reactive oxygen species was investigated to provide fundamental information on activation mechanisms when persulfate is used for in situ chemical oxidation (ISCO). Only four of the minerals (cobaltite, ilmenite, pyrite, and siderite) promoted the decomposition of persulfate more rapidly than persulfate–deionized water control systems. The other nine minerals decomposed persulfate at the same rate or more slowly than the control systems. Mineral-mediated persulfate activation was conducted with the addition of one of three probe compounds to detect the generation of reactive oxygen species: anisole (sulfate + hydroxyl radical), nitrobenzene (hydroxyl radical), and hexachloroethane (reductants and nucleophiles). The reduced mineral pyrite promoted rapid generation of sulfate + hydroxyl radical. However, the remainder of the minerals provided minimal potential for the generation of reactive oxygen species. The results of this research demonstrate that the majority of naturally occurring trace minerals do not activate persulfate to generate reactive oxygen species, and other mechanisms of activation are necessary to promote contaminant destruction in the subsurface during persulfate ISCO.

  6. Naturally Occurring Xanthones: Chemistry and Biology

    Directory of Open Access Journals (Sweden)

    J. S. Negi

    2013-01-01

    Full Text Available Xanthones are one of the biggest classes of compounds in natural product chemistry. A number of xanthones have been isolated from natural sources of higher plants, fungi, ferns, and lichens. They have gradually risen to great importance because of their medicinal properties. This review focuses on the types, isolation, characterization, biological applications, and biosynthesis of naturally occurring xanthones isolated so far. Different physicochemical and instrumental methods such as liquid-solid and liquid-liquid extraction, TLC, flash chromatography, column chromatography, IR, 1H NMR and 13C NMR spectroscopy, GLC, HPLC, GC, and LCMS have been widely used for isolation and structural elucidation of xanthones. Hepatoprotective, anticarcinogenic, antileprosy, antimalarial, antioxidant, anticholinergic, mutagenicity, radioprotective, immunomodulatory, antibone resorption, antiparasitic, neuraminidase inhibitory, anticomplement, antibacterial, antifungal, algicidal, anti-HIV, cardioprotective, antitumoral, antidiabetes, antihyperlipidemic, antiatherogenic, anti-inflammatory, antiulcer, antidiabetic, hypolipidemic, analgesic, antiasthmatic, antihistaminic, antiamoebic, diuretic, antidiarrheal, larvicidal, and ovicidal activities have been reported for natural occurring xanthones. To a certain extent, this review provides necessary foundation for further research and development of new medicines.

  7. Communicating Science

    Science.gov (United States)

    Holland, G. J.; McCaffrey, M. S.; Kiehl, J. T.; Schmidt, C.

    2010-12-01

    We are in an era of rapidly changing communication media, which is driving a major evolution in the modes of communicating science. In the past, a mainstay of scientific communication in popular media was through science “translators”; science journalists and presenters. These have now nearly disappeared and are being replaced by widespread dissemination through, e.g., the internet, blogs, YouTube and journalists who often have little scientific background and sharp deadlines. Thus, scientists are required to assume increasing responsibility for translating their scientific findings and calibrating their communications to non-technical audiences, a task for which they are often ill prepared, especially when it comes to controversial societal issues such as tobacco, evolution, and most recently climate change (Oreskes and Conway 2010). Such issues have been politicized and hi-jacked by ideological belief systems to such an extent that constructive dialogue is often impossible. Many scientists are excellent communicators, to their peers. But this requires careful attention to detail and logical explanation, open acknowledgement of uncertainties, and dispassionate delivery. These qualities become liabilities when communicating to a non-scientific audience where entertainment, attention grabbing, 15 second sound bites, and self assuredness reign (e.g. Olson 2009). Here we report on a program initiated by NCAR and UCAR to develop new approaches to science communication and to equip present and future scientists with the requisite skills. If we start from a sound scientific finding with general scientific consensus, such as the warming of the planet by greenhouse gases, then the primary emphasis moves from the “science” to the “art” of communication. The art cannot have free reign, however, as there remains a strong requirement for objectivity, honesty, consistency, and above all a resistance to advocating particular policy positions. Targeting audience

  8. Why Communicate

    Science.gov (United States)

    Illingworth, Samuel

    2015-04-01

    "Half the world is composed of people who have something to say and can't, and the other half who have nothing to say and keep on saying it." - Robert Frost In this age of digital soap boxes and half-truths, the importance of geoscientists as communicators cannot be underestimated, nor has there been a more important time for researchers to stand up and demand to be heard. So why is there still such an overwhelming public perception that scientists are poor communicators, and what can we do to change this? In this work I will present an overview of a number of successful initiatives that have been developed at Manchester Metropolitan University, and beyond, to ensure that science is communicated to a large variety of people, from policy makers to members of the local community. I will also present an overview of the emerging field of Science Communication, how it has changed in the past few decades from a one-way diatribe to a two-way discussion, and how this represents a possible new direction and career path for geoscientists. Anne Roe, the noted American psychologist, told us, "nothing in science has any value to society if it is not communicated." As geoscientists, we have a professional and moral obligation to ensure that we not only research the facts, but that we also present them in an informative and engaging manner, so that the rest of humanity can benefit from the fruits of our labour.

  9. Campylobacter jejuni adenosine triphosphate phosphoribosyltransferase is an active hexamer that is allosterically controlled by the twisting of a regulatory tail.

    Science.gov (United States)

    Mittelstädt, Gerd; Moggré, Gert-Jan; Panjikar, Santosh; Nazmi, Ali Reza; Parker, Emily J

    2016-08-01

    Adenosine triphosphate phosphoribosyltransferase (ATP-PRT) catalyzes the first committed step of the histidine biosynthesis in plants and microorganisms. Here, we present the functional and structural characterization of the ATP-PRT from the pathogenic ε-proteobacteria Campylobacter jejuni (CjeATP-PRT). This enzyme is a member of the long form (HisGL ) ATP-PRT and is allosterically inhibited by histidine, which binds to a remote regulatory domain, and competitively inhibited by AMP. In the crystalline form, CjeATP-PRT was found to adopt two distinctly different hexameric conformations, with an open homohexameric structure observed in the presence of substrate ATP, and a more compact closed form present when inhibitor histidine is bound. CjeATP-PRT was observed to adopt only a hexameric quaternary structure in solution, contradicting previous hypotheses favoring an allosteric mechanism driven by an oligomer equilibrium. Instead, this study supports the conclusion that the ATP-PRT long form hexamer is the active species; the tightening of this structure in response to remote histidine binding results in an inhibited enzyme. PMID:27191057

  10. 2.3 Å resolution cryo-EM structure of human p97 and mechanism of allosteric inhibition.

    Science.gov (United States)

    Banerjee, Soojay; Bartesaghi, Alberto; Merk, Alan; Rao, Prashant; Bulfer, Stacie L; Yan, Yongzhao; Green, Neal; Mroczkowski, Barbara; Neitz, R Jeffrey; Wipf, Peter; Falconieri, Veronica; Deshaies, Raymond J; Milne, Jacqueline L S; Huryn, Donna; Arkin, Michelle; Subramaniam, Sriram

    2016-02-19

    p97 is a hexameric AAA+ adenosine triphosphatase (ATPase) that is an attractive target for cancer drug development. We report cryo-electron microscopy (cryo-EM) structures for adenosine diphosphate (ADP)-bound, full-length, hexameric wild-type p97 in the presence and absence of an allosteric inhibitor at resolutions of 2.3 and 2.4 angstroms, respectively. We also report cryo-EM structures (at resolutions of ~3.3, 3.2, and 3.3 angstroms, respectively) for three distinct, coexisting functional states of p97 with occupancies of zero, one, or two molecules of adenosine 5'-O-(3-thiotriphosphate) (ATPγS) per protomer. A large corkscrew-like change in molecular architecture, coupled with upward displacement of the N-terminal domain, is observed only when ATPγS is bound to both the D1 and D2 domains of the protomer. These cryo-EM structures establish the sequence of nucleotide-driven structural changes in p97 at atomic resolution. They also enable elucidation of the binding mode of an allosteric small-molecule inhibitor to p97 and illustrate how inhibitor binding at the interface between the D1 and D2 domains prevents propagation of the conformational changes necessary for p97 function. PMID:26822609

  11. An Autoregulatory Mechanism Imposes Allosteric Control on the V(DJ Recombinase by Histone H3 Methylation

    Directory of Open Access Journals (Sweden)

    Chao Lu

    2015-01-01

    Full Text Available V(DJ recombination is initiated by a specialized transposase consisting of the subunits RAG-1 and RAG-2. The susceptibility of gene segments to DNA cleavage by the V(DJ recombinase is correlated with epigenetic modifications characteristic of active chromatin, including trimethylation of histone H3 on lysine 4 (H3K4me3. Engagement of H3K4me3 by a plant homeodomain (PHD in RAG-2 promotes recombination in vivo and stimulates DNA cleavage by RAG in vitro. We now show that H3K4me3 acts allosterically at the PHD finger to relieve autoinhibition imposed by a separate domain within RAG-2. Disruption of this autoinhibitory domain was associated with constitutive increases in recombination frequency, DNA cleavage activity, substrate binding affinity, and catalytic rate, thus mimicking the stimulatory effects of H3K4me3. Our observations support a model in which allosteric control of RAG is enforced by an autoinhibitory domain whose action is relieved by engagement of active chromatin.

  12. Lid L11 of the glutamine amidotransferase domain of CTP synthase mediates allosteric GTP activation of glutaminase activity

    DEFF Research Database (Denmark)

    Willemoës, Martin; Mølgaard, Anne; Johansson, Eva;

    2005-01-01

    GTP is an allosteric activator of CTP synthase and acts to increase the k(cat) for the glutamine-dependent CTP synthesis reaction. GTP is suggested, in part, to optimally orient the oxy-anion hole for hydrolysis of glutamine that takes place in the glutamine amidotransferase class I (GATase) domain...... position depending on the presence or absence of glutamine in the glutamine binding site. Displacement or rearrangement of this loop may provide a means for the suggested role of allosteric activation by GTP to optimize the oxy-anion hole for glutamine hydrolysis. Arg359, Gly360 and Glu362 of the...... enzyme behaved like wild-type enzyme. Apart from the G360A enzyme, the results from kinetic analysis of the enzymes altered at position 359 and 360 showed a 10- to 50-fold decrease in GTP activation of glutamine dependent CTP synthesis and concomitant four- to 10-fold increases in K(A) for GTP. The R359M...

  13. The M1 Muscarinic Positive Allosteric Modulator PQCA Improves Performance on Translatable Tests of Memory and Attention in Rhesus Monkeys.

    Science.gov (United States)

    Lange, Henry S; Cannon, Christopher E; Drott, Jason T; Kuduk, Scott D; Uslaner, Jason M

    2015-12-01

    Improved treatment of Alzheimer disease (AD) is a significant unmet medical need that is becoming even more critical given the rise in the number of patients and the substantial economic burden. The current standards of care, acetylcholinesterase inhibitors (AChEIs), are hindered by gastrointestinal side effects owing to their nonselective activation of muscarinic and nicotinic receptors. Recently, the highly selective M1 positive allosteric modulator PQCA (1-((4-cyano-4-(pyridine-2-yl)piperidin-1-yl)methyl-4-oxo-4 H-quinolizine-3-carboxylic acid) has been demonstrated to improve cognition in a variety of rodent and nonhuman primate cognition models without producing significant gastrointestinal side effects. Here we describe the effect of PQCA and the AChEI donepezil on two clinically relevant and highly translatable touchscreen cognition tasks in nonhuman primates: paired-associates learning (PAL) and the continuous-performance task (CPT). Blockade of muscarinic signaling by scopolamine produced significant impairments in both PAL and CPT. PQCA and donepezil attenuated the scopolamine deficits in both tasks, and the action of these two compounds was similar in magnitude. In addition, the combination of subeffective doses of PQCA and donepezil enhanced PAL performance. These results further suggest that M1-positive allosteric modulators, either as monotherapy or as an add-on to current standards of care, have potential to reduce the cognitive deficits associated with AD. PMID:26446308

  14. Allosteric Activation of Ubiquitin-Specific Proteases by β-Propeller Proteins UAF1 and WDR20.

    Science.gov (United States)

    Li, Heng; Lim, Kah Suan; Kim, Hyungjin; Hinds, Thomas R; Jo, Ukhyun; Mao, Haibin; Weller, Caroline E; Sun, Ji; Chatterjee, Champak; D'Andrea, Alan D; Zheng, Ning

    2016-07-21

    Ubiquitin-specific proteases (USPs) constitute the largest family of deubiquitinating enzymes, whose catalytic competency is often modulated by their binding partners through unknown mechanisms. Here we report on a series of crystallographic and biochemical analyses of an evolutionarily conserved deubiquitinase, USP12, which is activated by two β-propeller proteins, UAF1 and WDR20. Our structures reveal that UAF1 and WDR20 interact with USP12 at two distinct sites far from its catalytic center. Without increasing the substrate affinity of USP12, the two β-propeller proteins potentiate the enzyme through different allosteric mechanisms. UAF1 docks at the distal end of the USP12 Fingers domain and induces a cascade of structural changes that reach a critical ubiquitin-contacting loop adjacent to the catalytic cleft. By contrast, WDR20 anchors at the base of this loop and remotely modulates the catalytic center of the enzyme. Our results provide a mechanistic example for allosteric activation of USPs by their regulatory partners. PMID:27373336

  15. PARTICULARITIES OF COMMUNICATION IN RURAL TOURISM

    Directory of Open Access Journals (Sweden)

    Svetlana SASU

    2014-06-01

    Full Text Available The social aspect of rural tourism enhances its value as a communicative process because Tourism is an industry with a difference. There is an undeniable exchange between places and people. This exchange is what is meant bycommunication. Communication happens at many levels (even for one single action, in many different ways, andfor most beings, as well as certain machines. Communication requires a sender, a message, and an intendedrecipient, although the receiver need not be present or aware of the sender's intent to communicate at the time ofcommunication; thus communication can occur across vast distances in time and space. Communication requiresthat the communicating parties share an area of communicative commonality. The communication process iscomplete once the receiver has understood the sender. Thus, communication is a two- way process. The interactionof the tourist with the places he visits and the people he meets is therefore, a form of communication in which boththe visitor and the visited form a communication cycle. A considerable amount of weight age is given to the power ofimpressions on the mind of a person living in the twenty-first century. One of the most important aspects of ruraltourism is the communication of the impressions created in the minds of tourists. These include non-verbal aspects -- sights and sounds communicate a general impression-- and the verbal aspect of communication-- language playsan important role in creating impressions.

  16. Pilomyxoid Astrocytoma Occurring in the Third Ventricle

    Directory of Open Access Journals (Sweden)

    Sanghyeon Kim

    2015-01-01

    Full Text Available Pilomyxoid astrocytoma (PMA is a rare central nervous system tumor that has been included in the 2007 World Health Organization Classification of Tumors of the Central Nervous System. Due to its more aggressive behavior, PMA is classified as Grade II neoplasm by the World Health Organization. PMA predominantly affects the hypothalamic/chiasmatic region and occurs in children (mean age of occurrence = 10 months. We report a case of a 24-year-old man who presented with headache, nausea, and vomiting. Brain CT and MRI revealed a mass occupying only the third ventricle. We performed partial resection. Histological findings, including monophasic growth with a myxoid background, and absence of Rosenthal fibers or eosinophilic granular bodies, as well as the strong positivity for glial fibrillary acidic protein were consistent with PMA.

  17. 14 CFR Special Federal Aviation... - Alternative Communications and Dispatching Procedures

    Science.gov (United States)

    2010-01-01

    ... dispatch communication system. ii. Gaps in communication are not over the entire route, but only over portions of the route. iii. When communication gaps occur, they occur due to one or more of the following... plan or schedule for coming into compliance with the requirements in § 121.99 of this chapter. b....

  18. Communication Problems in Crisis Response

    OpenAIRE

    Lundberg, Jonas; Asplund, Mikael

    2011-01-01

    This paper describes five problem areas of communication that occur during crisis response. These areas arecommunication infrastructure, situation awareness, individual and organizational common ground, form andcontent of messages, and communication paths through organizations. Five focus groups with Swedish fieldpersonnel from national and international crises were performed. The main contribution of this article is ahypothesis, based on the outcomes of the focus groups, about the relation b...

  19. Communication and optimal hierarchical networks

    OpenAIRE

    Guimera, R.; Arenas, A.; Diaz-Guilera, A.

    2001-01-01

    We study a general and simple model for communication processes. In the model, agents in a network (in particular, an organization) interchange information packets following simple rules that take into account the limited capability of the agents to deal with packets and the cost associated to the existence of open communication channels. Due to the limitation in the capability, the network collapses under certain conditions. We focus on when the collapse occurs for hierarchical networks and ...

  20. Substituting Quantum Entanglement for Communication

    OpenAIRE

    Cleve, Richard; Buhrman, Harry

    1997-01-01

    We show that quantum entanglement can be used as a substitute for communication when the goal is to compute a function whose input data is distributed among remote parties. Specifically, we show that, for a particular function among three parties (each of which possesses part of the function's input), a prior quantum entanglement enables one of them to learn the value of the function with only two bits of communication occurring among the parties, whereas, without quantum entanglement, three ...

  1. Communication & Management

    CERN Multimedia

    Nathalie Dumeaux

    2006-01-01

    Calendar of courses for September to December 2006 Please check our Web site to find out the number of places available, which may vary. Management Curriculum 2nd semester 2006 Titles Dates Language Quality Management 18, 19 September Bilingual Managing Teams 19, 20, 21 September English Communicating Effectively - Residential 20, 21, 22 septembre Bilingual (Full) Personal Awareness & Impact 26, 27, 28 September Bilingual Introduction to Leadership 4, 5, 6 October Bilingue IProject Scheduling & Costing 12, 13 October English CDP-SL part 1 Several sessions Dates to be fixed English or French Personal Awareness & Impact 23, 24 October Bilingual Communicating to Convince 23, 24, 25 October Bilingual CDP-GL part 2 25, 26, 27 October English CDP-GL part 1 Dates to be fixed Bilingual Risk Management 20, 21 December Bilingual Communication curriculum 2nd semester 2006 Titles Dates Language Techniques d'exposé et de présentation 18, 19 s...

  2. Management & Communication

    CERN Multimedia

    2006-01-01

    Calendar of courses for September to December 2006 Please check our Web site to find out the number of places available, which may vary. Management Curriculum 2nd semester 2006 Titles Dates Language Quality Management 18, 19 September Bilingual Managing Teams 19, 20, 21 September English Communicating Effectively - Residential 20, 21, 22 septembre Bilingual (Full) Personal Awareness & Impact 26, 27, 28 September Bilingual Introduction to Leadership 4, 5, 6 October Bilingue IProject Scheduling & Costing 12, 13 October English CDP-SL part 1 Several sessions Dates to be fixed English or French Personal Awareness & Impact 23, 24 October Bilingual Communicating to Convince 23, 24, 25 October Bilingual CDP-GL part 2 25, 26, 27 October English CDP-GL part 1 Dates to be fixed Bilingual Risk Management 20, 21 December Bilingual Communication curriculum 2nd semester 2006 Titles Dates Language Techniques d'exposé et de présentation 18, 19 sept...

  3. Interlimb communication

    DEFF Research Database (Denmark)

    Stevenson, Andrew James Thomas

    A continual coordination between the two legs is necessary for maintaining a symmetric walking pattern and adapting to changes in the external environment. Recent evidence in animals and humans suggests that spinal interneuronal circuits under supraspinal control may mediate communication between...... the lower limbs. The overall objective of the present thesis was to further investigate and elucidate neural pathways underlying interlimb communication in humans, focusing primarily on the possible interlimb connections to the biceps femoris muscle. The major aims were 1) to investigate whether interlimb...... walking (Study IV). The results of the this thesis provide new insights into the neural mechanisms underlying human interlimb communication, as well as their functional relevance to human locomotion. Although it is difficult to propose the exact neural pathways mediating interlimb reflexes...

  4. Potent Allosteric Dengue Virus NS5 Polymerase Inhibitors: Mechanism of Action and Resistance Profiling.

    Science.gov (United States)

    Lim, Siew Pheng; Noble, Christian Guy; Seh, Cheah Chen; Soh, Tingjin Sherryl; El Sahili, Abbas; Chan, Grace Kar Yarn; Lescar, Julien; Arora, Rishi; Benson, Timothy; Nilar, Shahul; Manjunatha, Ujjini; Wan, Kah Fei; Dong, Hongping; Xie, Xuping; Shi, Pei-Yong; Yokokawa, Fumiaki

    2016-08-01

    Flaviviruses comprise major emerging pathogens such as dengue virus (DENV) or Zika virus (ZIKV). The flavivirus RNA genome is replicated by the RNA-dependent-RNA polymerase (RdRp) domain of non-structural protein 5 (NS5). This essential enzymatic activity renders the RdRp attractive for antiviral therapy. NS5 synthesizes viral RNA via a "de novo" initiation mechanism. Crystal structures of the flavivirus RdRp revealed a "closed" conformation reminiscent of a pre-initiation state, with a well ordered priming loop that extrudes from the thumb subdomain into the dsRNA exit tunnel, close to the "GDD" active site. To-date, no allosteric pockets have been identified for the RdRp, and compound screening campaigns did not yield suitable drug candidates. Using fragment-based screening via X-ray crystallography, we found a fragment that bound to a pocket of the apo-DENV RdRp close to its active site (termed "N pocket"). Structure-guided improvements yielded DENV pan-serotype inhibitors of the RdRp de novo initiation activity with nano-molar potency that also impeded elongation activity at micro-molar concentrations. Inhibitors exhibited mixed inhibition kinetics with respect to competition with the RNA or GTP substrate. The best compounds have EC50 values of 1-2 μM against all four DENV serotypes in cell culture assays. Genome-sequencing of compound-resistant DENV replicons, identified amino acid changes that mapped to the N pocket. Since inhibitors bind at the thumb/palm interface of the RdRp, this class of compounds is proposed to hinder RdRp conformational changes during its transition from initiation to elongation. This is the first report of a class of pan-serotype and cell-active DENV RdRp inhibitors. Given the evolutionary conservation of residues lining the N pocket, these molecules offer insights to treat other serious conditions caused by flaviviruses. PMID:27500641

  5. Potent Allosteric Dengue Virus NS5 Polymerase Inhibitors: Mechanism of Action and Resistance Profiling

    Science.gov (United States)

    Lim, Siew Pheng; Noble, Christian Guy; Seh, Cheah Chen; Soh, Tingjin Sherryl; El Sahili, Abbas; Chan, Grace Kar Yarn; Lescar, Julien; Arora, Rishi; Benson, Timothy; Nilar, Shahul; Manjunatha, Ujjini; Wan, Kah Fei; Dong, Hongping; Xie, Xuping; Yokokawa, Fumiaki

    2016-01-01

    Flaviviruses comprise major emerging pathogens such as dengue virus (DENV) or Zika virus (ZIKV). The flavivirus RNA genome is replicated by the RNA-dependent-RNA polymerase (RdRp) domain of non-structural protein 5 (NS5). This essential enzymatic activity renders the RdRp attractive for antiviral therapy. NS5 synthesizes viral RNA via a “de novo” initiation mechanism. Crystal structures of the flavivirus RdRp revealed a “closed” conformation reminiscent of a pre-initiation state, with a well ordered priming loop that extrudes from the thumb subdomain into the dsRNA exit tunnel, close to the “GDD” active site. To-date, no allosteric pockets have been identified for the RdRp, and compound screening campaigns did not yield suitable drug candidates. Using fragment-based screening via X-ray crystallography, we found a fragment that bound to a pocket of the apo-DENV RdRp close to its active site (termed “N pocket”). Structure-guided improvements yielded DENV pan-serotype inhibitors of the RdRp de novo initiation activity with nano-molar potency that also impeded elongation activity at micro-molar concentrations. Inhibitors exhibited mixed inhibition kinetics with respect to competition with the RNA or GTP substrate. The best compounds have EC50 values of 1–2 μM against all four DENV serotypes in cell culture assays. Genome-sequencing of compound-resistant DENV replicons, identified amino acid changes that mapped to the N pocket. Since inhibitors bind at the thumb/palm interface of the RdRp, this class of compounds is proposed to hinder RdRp conformational changes during its transition from initiation to elongation. This is the first report of a class of pan-serotype and cell-active DENV RdRp inhibitors. Given the evolutionary conservation of residues lining the N pocket, these molecules offer insights to treat other serious conditions caused by flaviviruses. PMID:27500641

  6. Problems That Lead to the Failure in Language Communication

    OpenAIRE

    Shenghua Yan

    2007-01-01

    A language is the most important tool for communication, yet misunderstanding of language often occurs in our daily communication. This paper illustrates some problems that lead to the failure of language communication and points out that it is necessary to avoid such problems for an effective and clear communication.

  7. Constructive communication

    CERN Document Server

    Ellis, Richard

    2012-01-01

    Richard Ellis is a consultant in communications and the successful author of 'Communication for Engineers'. In each chapter he highlights key points and situations, and provides exercises to consolidate what has already been learnt. The book ends with a 'toolbox' of useful information on subjects such as writing letters, spelling, punctuation, using abbreviations, studying for exams, using libraries and training.Written in clear, informative English, with the emphasis on the practical, this book is essential reading for both students and professionals in the con

  8. Communications standards

    CERN Document Server

    Stokes, A V

    1986-01-01

    Communications Standards deals with the standardization of computer communication networks. This book examines the types of local area networks (LANs) that have been developed and looks at some of the relevant protocols in more detail. The work of Project 802 is briefly discussed, along with a protocol which has developed from one of the LAN standards and is now a de facto standard in one particular area, namely the Manufacturing Automation Protocol (MAP). Factors that affect the usage of networks, such as network management and security, are also considered. This book is divided into three se

  9. Digital communication

    CERN Document Server

    Das, Apurba

    2010-01-01

    ""Digital Communications"" presents the theory and application of the philosophy of Digital Communication systems in a unique but lucid form. This book inserts equal importance to the theory and application aspect of the subject whereby the authors selected a wide class of problems. The Salient features of the book are: the foundation of Fourier series, Transform and wavelets are introduces in a unique way but in lucid language; the application area is rich and resemblance to the present trend of research, as we are attached with those areas professionally; a CD is included which contains code

  10. Introduction to naturally occurring radioactive material

    International Nuclear Information System (INIS)

    Naturally occurring radioactive material (NORM) is everywhere; we are exposed to it every day. It is found in our bodies, the food we eat, the places where we live and work, and in products we use. Some industrial practices involving natural resources concentrate these radionuclides to a degree that they may pose risk to humans and the environment if they are not controlled. This session will concentrate on diffuse sources of technologically-enhanced (TE) NORM, which are generally large-volume, low-activity waste streams produced by industries such as mineral mining, ore benefication, production of phosphate Fertilizers, water treatment and purification, and oil and gas production. The majority of radionuclides in TENORM are found in the uranium and thorium decay chains. Radium and its subsequent decay products (radon) are the principal radionuclides used in characterizing the redistribution of TENORM in the environment by human activity. We will briefly review other radionuclides occurring in nature (potassium and rubidium) that contribute primarily to background doses. TENORM is found in many waste streams; for example, scrap metal, sludges, slags, fluids, and is being discovered in industries traditionally not thought of as affected by radionuclide contamination. Not only the forms and volumes, but the levels of radioactivity in TENORM vary. Current discussions about the validity of the linear no dose threshold theory are central to the TENORM issue. TENORM is not regulated by the Atomic Energy Act or other Federal regulations. Control and regulation of TENORM is not consistent from industry to industry nor from state to state. Proposed regulations are moving from concentration-based standards to dose-based standards. So when is TENORM a problem? Where is it a problem? That depends on when, where, and whom you talk to exclamation point We will start by reviewing background radioactivity, then we will proceed to the geology, mobility, and variability of these

  11. A novel dualistic profile of an allosteric AMPA receptor modulator identified through studies on recombinant receptors, mouse hippocampal synapses and crystal structures

    DEFF Research Database (Denmark)

    Christiansen, G B; Harbak, Barbara; Hede, S E;

    2015-01-01

    Positive allosteric modulators (PAMs) of 2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid (AMPA) receptors receive increasing interest as therapeutic drugs and have long served as important experimental tools in the study of the molecular mechanisms underlying glutamate-mediated neurotra...

  12. Changes of cooperativity between N-methylscopolamine and allosteric modulators alcuronium and gallamine induced by mutations of external loops of muscarinic M(3) receptors

    Czech Academy of Sciences Publication Activity Database

    Krejčí, Alena; Tuček, Stanislav

    2001-01-01

    Roč. 60, č. 4 (2001), s. 761-767. ISSN 0026-895X R&D Projects: GA ČR GA309/99/0214 Institutional research plan: CEZ:AV0Z5011922 Keywords : muscarinic receptors * allosteric modulators Subject RIV: FH - Neurology Impact factor: 5.297, year: 2001

  13. Uranium occurence in California near Bucaramanga (Columbia)

    International Nuclear Information System (INIS)

    The mining district of California, Bucaramanga, is on the west side of the Cordillera Oriental in the Santander massif region. The oldest rocks of the area form a complex of metamorphites and migmatites of the predevonic age. Amphibolite various types of paragneiss and orthogneiss are represented. Several stages of metamorphism can be documented in some rocks, as well as double anatexis. Triassic to jurassic quarz diorites and leukogranites show wide distribution. Porphyric rocks of granodioritic to granitic composition, to which the uranium mineralization is mainly bonded, intruded into the sediments of the lower cretaceous. Atomic absorption spectral analyses were carried out for the elements Cu, Zn and Li, as well as the uranium contents of some samples using fluorimetry. Uranium is primarily bonded to pitch blende and coffinite. The latter mostly occur in fine distribution grown in quarz and belong to the most recent mineralization phase. Autunite, meta-autunite, torbernite, meta-torbernite, zeunerite, meta-zeunerite and meta uranocircite detected as secondary uranium minerals. (orig./HP)

  14. Crisis Communication: The Business Communicator's Strategies for Communicating under Stress.

    Science.gov (United States)

    Vielhaber, Mary E.

    1990-01-01

    Uses the 1979 Three Mile Island nuclear plant accident to illustrate the communication problems embedded in a crisis. Describes the reactions created by the stress related to crisis. Suggests business communication strategies for improving communication to the public. (SR)

  15. The tertiary origin of the allosteric activation of E. coli glucosamine-6-phosphate deaminase studied by sol-gel nanoencapsulation of its T conformer.

    Directory of Open Access Journals (Sweden)

    Sergio Zonszein

    Full Text Available The role of tertiary conformational changes associated to ligand binding was explored using the allosteric enzyme glucosamine-6-phosphate (GlcN6P deaminase from Escherichia coli (EcGNPDA as an experimental model. This is an enzyme of amino sugar catabolism that deaminates GlcN6P, giving fructose 6-phosphate and ammonia, and is allosterically activated by N-acetylglucosamine 6-phosphate (GlcNAc6P. We resorted to the nanoencapsulation of this enzyme in wet silica sol-gels for studying the role of intrasubunit local mobility in its allosteric activation under the suppression of quaternary transition. The gel-trapped enzyme lost its characteristic homotropic cooperativity while keeping its catalytic properties and the allosteric activation by GlcNAc6P. The nanoencapsulation keeps the enzyme in the T quaternary conformation, making possible the study of its allosteric activation under a condition that is not possible to attain in a soluble phase. The involved local transition was slowed down by nanoencapsulation, thus easing the fluorometric analysis of its relaxation kinetics, which revealed an induced-fit mechanism. The absence of cooperativity produced allosterically activated transitory states displaying velocity against substrate concentration curves with apparent negative cooperativity, due to the simultaneous presence of subunits with different substrate affinities. Reaction kinetics experiments performed at different tertiary conformational relaxation times also reveal the sequential nature of the allosteric activation. We assumed as a minimal model the existence of two tertiary states, t and r, of low and high affinity, respectively, for the substrate and the activator. By fitting the velocity-substrate curves as a linear combination of two hyperbolic functions with Kt and Kr as KM values, we obtained comparable values to those reported for the quaternary conformers in solution fitted to MWC model. These results are discussed in the

  16. Communication Skills.

    Science.gov (United States)

    Carlisle, Lynn

    This document presents one module in a set of training resources for trainers to use with parents and/or professionals serving children with disabilities; focus is on communication skills. The modules stress content and activities that build skills and offer resources to promote parent-professional collaboration. Each training module takes about 2…

  17. Situated communication:

    DEFF Research Database (Denmark)

    Kampf, Constance

    .  Understanding the Internet as an extension of identity is a fruitful metaphor when identities are analyzed in rhetorical contexts.  Howard (2004) argues that "Understanding society requires that we study media embeddedness-how new communication tools are embedded in our lives and how our lives are embedded in...

  18. Magnetostatic communication

    Science.gov (United States)

    Daily, William D.

    2008-02-26

    A system for providing communication of information by modulating a magnetostatic field with a magnetostatic transmitter that modulates said magnetostatic field to contain the information and detecting the information in the modulated field at a distance with a magnetostatic detector that detects the modulated magnetic field containing the information.

  19. COMMUNICATIONS GROUP

    CERN Multimedia

    L. Taylor

    2010-01-01

    The recently established CMS Communications Group, led by Lucas Taylor, has been busy in all three of its main are areas of responsibility: Communications Infrastructure, Information Systems, and Outreach and Education Communications Infrastructure The damage caused by the flooding of the CMS Centre@CERN on 21st December has been completely repaired and all systems are back in operation. Major repairs were made to the roofs, ceilings and one third of the floor had to be completely replaced. Throughout these works, the CMS Centre was kept operating and even hosted a major press event for first 7 TeV collisions, as described below. Incremental work behind the scenes is steadily improving the quality of the CMS communications infrastructure, particularly Webcasting, video conferencing, and meeting rooms at CERN. CERN/IT is also deploying a pilot service of a new videoconference tool called Vidyo, to assess whether it might provide an enhanced service at a lower cost, compared to the EVO tool currently in w...

  20. Emergency Communication

    OpenAIRE

    Shaw, Rajib; Peary, Brett; Ideta, Ai; Takeuchi, Yukiko

    2012-01-01

    The Great East Japan Earthquake (GEJE) caused immense damage and congestion in telephone infrastructure, including 1.9 million fixed-line services and 29,000 mobile phone base stations. Government radio communication infrastructure was also seriously damaged. Voice messages were widely used to confirm whether family members and relatives were safe, and satellite phones played a crucial rol...

  1. Quantum communications

    CERN Document Server

    Cariolaro, Gianfranco

    2015-01-01

    This book demonstrates that a quantum communication system using the coherent light of a laser can achieve performance orders of magnitude superior to classical optical communications Quantum Communications provides the Masters and PhD signals or communications student with a complete basics-to-applications course in using the principles of quantum mechanics to provide cutting-edge telecommunications. Assuming only knowledge of elementary probability, complex analysis and optics, the book guides its reader through the fundamentals of vector and Hilbert spaces and the necessary quantum-mechanical ideas, simply formulated in four postulates. A turn to practical matters begins with and is then developed by: ·         development of the concept of quantum decision, emphasizing the optimization of measurements to extract useful information from a quantum system; ·         general formulation of a transmitter–receiver system ·         particular treatment of the most popular quantum co...

  2. COMMUNICATIONS GROUP

    CERN Multimedia

    L. Taylor

    2011-01-01

    The CMS Communications Group has been busy in all three areas of its responsibility: (1) Communications Infrastructure, (2) Information Systems, and (3) Outreach and Education. Communications Infrastructure The 55 CMS Centres worldwide are well used by physicists working on remote CMS shifts, Computing operations, data quality monitoring, data analysis and outreach. The CMS Centre@CERN in Meyrin, is the centre of the CMS Offline and Computing operations, and a number of subdetector shifts can now take place there, rather than in the main Control Room at P5. A new CMS meeting room has been equipped for videoconferencing in building 42, next to building 40. Our building 28 meeting room and the facilities at P5 will be refurbished soon and plans are underway to steadily upgrade the ageing equipment in all 15 CMS meeting rooms at CERN. The CMS evaluation of the Vidyo tool indicates that it is not yet ready to be considered as a potential replacement for EVO. The Communications Group provides the CMS-TV (web) cha...

  3. COMMUNICATIONS GROUP

    CERN Multimedia

    L. Taylor

    2010-01-01

    The CMS Communications Group, established at the start of 2010, has been strengthening the activities in all three areas of its responsibility: (1) Communications Infrastructure, (2) Information Systems, and (3) Outreach and Education. Communications Infrastructure The Communications Group has invested a lot of effort to support the operations needs of CMS. Hence, the CMS Centres where physicists work on remote CMS shifts, Data Quality Monitoring, and Data Analysis are running very smoothly. There are now 55 CMS Centres worldwide, up from just 16 at the start of CMS data-taking. The latest to join are Imperial College London, the University of Iowa, and the Università di Napoli. The CMS Centre@CERN in Meyrin, which is now full repaired after the major flooding at the beginning of the year, has been at the centre of CMS offline and computing operations, most recently hosting a large fraction of the CMS Heavy Ion community during the lead-lead run. A number of sub-detector shifts can now take pla...

  4. Health communication

    DEFF Research Database (Denmark)

    Sørensen, Mariann B.

    communication changes from information to conversation and negotiation of a chared understanding and challenges the concept of professionalism. The success of conversations depends on the interactions and the capacity to deal with several voices in a complex context. The study discusses the opportunity...

  5. Teaching communication skills: beyond wishful thinking.

    Science.gov (United States)

    Junod Perron, Noelle; Sommer, Johanna; Louis-Simonet, Martine; Nendaz, Mathieu

    2015-01-01

    Communication skills tend to decline with time unless they are regularly recalled and practiced. However, most medical schools still deliver clinical communication training only during pre-clinical years although the clinical environment is considered to be ideal for acquiring and teaching clinical communication. The aim of this article is to review the barriers that prevent communication skills teaching and training from occurring in clinical practice and describe strategies that may help enhance such activities. Barriers occur at several levels: students, junior doctors and clinical supervisors sometimes have negative attitudes towards communication training; structured training in communication skills is often insufficient; clinical supervisors behave as poor role models and lack effective communication and teaching skills; finally, there are organisational constraints such as lack of time, competing priorities, weak hierarchy support and lack of positive incentives for using, training or teaching good communication skills in clinical practice. Given the difficulty of assessing transfer of communication skills in practice, only few studies describe successful educational interventions. In order to optimise communication skills learning in practice, there is need to: (1.) modify the climate and structure of the working environment so that that use, training and teaching of good communication skills in clinical practice becomes valued, supported and rewarded; (2.) extend communication skills training to any field of medicine; (3.) provide regular structured trainings and tailor them to trainees' needs. Practical implications of such findings are discussed at the end of this review. PMID:25664624

  6. Astronomy Communication

    Science.gov (United States)

    Heck, A.; Madsen, C.

    2003-07-01

    Astronomers communicate all the time, with colleagues of course, but also with managers and administrators, with decision makers and takers, with social representatives, with the news media, and with the society at large. Education is naturally part of the process. Astronomy communication must take into account several specificities: the astronomy community is rather compact and well organized world-wide; astronomy has penetrated the general public remarkably well with an extensive network of associations and organizations of aficionados all over the world. Also, as a result of the huge amount of data accumulated and by necessity for their extensive international collaborations, astronomers have pioneered the development of distributed resources, electronic communications and networks coupled to advanced methodologies and technologies, often much before they become of common world-wide usage. This book is filling up a gap in the astronomy-related literature by providing a set of chapters not only of direct interest to astronomy communication, but also well beyond it. The experts contributing to this book have done their best to write in a way understandable to readers not necessarily hyperspecialized in astronomy nor in communication techniques while providing specific detailed information, as well as plenty of pointers and bibliographic elements. This book will be very useful for researchers, teachers, editors, publishers, librarians, computer scientists, sociologists of science, research planners and strategists, project managers, public-relations officers, plus those in charge of astronomy-related organizations, as well as for students aiming at a career in astronomy or related space science. Link: http://www.wkap.nl/prod/b/1-4020-1345-0

  7. Human exposure to naturally occurring hydroquinone.

    Science.gov (United States)

    Deisinger, P J; Hill, T S; English, J C

    1996-01-01

    Hydroquinone (HQ) is a nonvolatile chemical used in the photographic, rubber, chemical, and cosmetic industries. HQ is also known to occur in nature as the beta-D-glucopyranoside conjugate (arbutin), and free HQ is a known component of cigarette smoke. Low concentrations of HQ have been detected in the urine and plasma of humans with no occupational or other known exposure to HQ. The studies reported here investigate dietary and other potential sources of HQ and their contribution to HQ concentrations in the plasma and urine of human volunteers. Analysis of possible food sources of HQ by GC indicated significant amounts of arbutin in wheat products (1-10 ppm), pears (4-15 ppm), and coffee and tea (0.1 ppm). Free HQ was found in coffee (0.2 ppm), red wine (0.5 ppm), wheat cereals (0.2-0.4 ppm), and broccoli (0.1 ppm). After consuming a meal including arbutin- and HQ-containing foods, volunteers showed significant increases in plasma and urinary levels of HQ and its conjugated metabolites (total HQ). Mean plasma concentrations of total HQ peaked at 5 times background levels at 2 h after the completion of the meal, and mean urinary excretion rates of total HQ peaked at 12 times background at 2-3 h after the meal. Immediately after smoking four cigarettes in approximately 30 min, mean plasma concentrations of total HQ were maximally 1.5 times background levels; mean urinary excretion rates of total HQ peaked at 2.5 times background at 1-3 h after smoking. These data indicate that considerable human exposure to HQ can result from plant-derived dietary sources and, to a lesser extent, from cigarette smoke. PMID:8568910

  8. Digital communication communication, multimedia, security

    CERN Document Server

    Meinel, Christoph

    2014-01-01

    The authors give a detailed summary about the fundamentals and the historical background of digital communication. This includes an overview of the encoding principles and algorithms of textual information, audio information, as well as images, graphics, and video in the Internet. Furthermore the fundamentals of computer networking, digital security and cryptography are covered. Thus, the book provides a well-founded access to communication technology of computer networks, the internet and the WWW. Numerous pictures and images, a subject-index and a detailed list of historical personalities in

  9. Interreligious Communication (Definition, Concepts, Situation

    Directory of Open Access Journals (Sweden)

    Hasan Bashir

    2016-01-01

    Full Text Available Abstract Religion and monotheistic beliefs are the bases of the human societies and culture and communications are the most important manifestations of these bases. About the three elements of religion, culture and communications, which act as the distinctions of human beings from other beings, and the relationship among them, many discussions have been occurred. In this article, the definitions offered for religion, culture and communication and their relationship, using the literature governing the Intercultural Communication and Cross-cultural Communication as two subjects discussed in the field of Cultural Communication and International Communication, have been reviewed and tried through a novel method to promote the level of religion from a concept usually seen as something such as race, ethnic, identity and life style under the title of international communication and cultural communication to a much higher position and place it under the title of interreligious communication. Following creation of a new field of study, many of the scholars and thinkers who are concerned about that field get together and focus of its issues and try to offer definitions and divisions about the subject. Later, after accumulation of scientific materials about different issues in the field, the human knowledge in that subject starts to develop further and in a more organized way. In this regard, first, the preferred definitions of religion, culture, communication, and Interreligious Communication will be offered. Accordingly, every society includes a meaning structure which is called culture and communication would act as an interaction tool in this system whose task is coding and decoding. Religion is considered the origin of culture and the director of communication. Based on these primary definitions, the interreligious communication is defined as: the relationship between or among the monotheistic religions based on the common understanding of religious

  10. Allosterism in human complement component 5a ((h)C5a): a damper of C5a receptor (C5aR) signaling.

    Science.gov (United States)

    Rana, Soumendra; Sahoo, Amita Rani; Majhi, Bharat Kumar

    2016-06-01

    The phenomena of allosterism continues to advance the field of drug discovery, by illuminating gainful insights for many key processes, related to the structure-function relationships in proteins and enzymes, including the transmembrane G-protein coupled receptors (GPCRs), both in normal as well as in the disease states. However, allosterism is completely unexplored in the native protein ligands, especially when a small covalent change significantly modulates the pharmacology of the protein ligands toward the signaling axes of the GPCRs. One such example is the human C5a ((h)C5a), the potent cationic anaphylatoxin that engages C5aR and C5L2 to elicit numerous immunological and non-immunological responses in humans. From the recently available structure-function data, it is clear that unlike the mouse C5a ((m)C5a), the (h)C5a displays conformational heterogeneity. However, the molecular basis of such conformational heterogeneity, otherwise allosterism in (h)C5a and its precise contribution toward the overall C5aR signaling is not known. This study attempts to decipher the functional role of allosterism in (h)C5a, by exploring the inherent conformational dynamics in (m)C5a, (h)C5a and in its point mutants, including the proteolytic mutant des-Arg(74)-(h)C5a. Prima facie, the comparative molecular dynamics study, over total 500 ns, identifies Arg(74)-Tyr(23) and Arg(37)-Phe(51) "cation-π" pairs as the molecular "allosteric switches" on (h)C5a that potentially functions as a damper of C5aR signaling. PMID:26212097

  11. Brain mechanisms underlying human communication

    Directory of Open Access Journals (Sweden)

    Matthijs L Noordzij

    2009-07-01

    Full Text Available Human communication has been described as involving the coding-decoding of a conventional symbol system, which could be supported by parts of the human motor system (i.e. the “mirror neurons system”. However, this view does not explain how these conventions could develop in the first place. Here we target the neglected but crucial issue of how people organize their non-verbal behavior to communicate a given intention without pre-established conventions. We have measured behavioral and brain responses in pairs of subjects during communicative exchanges occurring in a real, interactive, on-line social context. In two fMRI studies, we found robust evidence that planning new communicative actions (by a sender and recognizing the communicative intention of the same actions (by a receiver relied on spatially overlapping portions of their brains (the right posterior superior temporal sulcus. The response of this region was lateralized to the right hemisphere, modulated by the ambiguity in meaning of the communicative acts, but not by their sensorimotor complexity. These results indicate that the sender of a communicative signal uses his own intention recognition system to make a prediction of the intention recognition performed by the receiver. This finding supports the notion that our communicative abilities are distinct from both sensorimotor processes and language abilities.

  12. Multiple transmembrane binding sites for p-trifluoromethyldiazirinyl-etomidate, a photoreactive Torpedo nicotinic acetylcholine receptor allosteric inhibitor.

    Science.gov (United States)

    Hamouda, Ayman K; Stewart, Deirdre S; Husain, S Shaukat; Cohen, Jonathan B

    2011-06-10

    Photoreactive derivatives of the general anesthetic etomidate have been developed to identify their binding sites in γ-aminobutyric acid, type A and nicotinic acetylcholine receptors. One such drug, [(3)H]TDBzl-etomidate (4-[3-(trifluoromethyl)-3H-diazirin-3-yl]benzyl-[(3)H]1-(1-phenylethyl)-1H-imidazole-5-carboxylate), acts as a positive allosteric potentiator of Torpedo nACh receptor (nAChR) and binds to a novel site in the transmembrane domain at the γ-α subunit interface. To extend our understanding of the locations of allosteric modulator binding sites in the nAChR, we now characterize the interactions of a second aryl diazirine etomidate derivative, TFD-etomidate (ethyl-1-(1-(4-(3-trifluoromethyl)-3H-diazirin-3-yl)phenylethyl)-1H-imidazole-5-carboxylate). TFD-etomidate inhibited acetylcholine-induced currents with an IC(50) = 4 μM, whereas it inhibited the binding of [(3)H]phencyclidine to the Torpedo nAChR ion channel in the resting and desensitized states with IC(50) values of 2.5 and 0.7 mm, respectively. Similar to [(3)H]TDBzl-etomidate, [(3)H]TFD-etomidate bound to a site at the γ-α subunit interface, photolabeling αM2-10 (αSer-252) and γMet-295 and γMet-299 within γM3, and to a site in the ion channel, photolabeling amino acids within each subunit M2 helix that line the lumen of the ion channel. In addition, [(3)H]TFD-etomidate photolabeled in an agonist-dependent manner amino acids within the δ subunit M2-M3 loop (δIle-288) and the δ subunit transmembrane helix bundle (δPhe-232 and δCys-236 within δM1). The fact that TFD-etomidate does not compete with ion channel blockers at concentrations that inhibit acetylcholine responses indicates that binding to sites at the γ-α subunit interface and/or within δ subunit helix bundle mediates the TFD-etomidate inhibitory effect. These results also suggest that the γ-α subunit interface is a binding site for Torpedo nAChR negative allosteric modulators (TFD-etomidate) and for positive

  13. Organizational Communication: ERIC Report.

    Science.gov (United States)

    Boileau, Don M.

    1984-01-01

    Presents abstracts from "Resources in Education" on (1) teaching about women in organizational communication; (2) communication as part of job satisfaction; and (3) research in organizational communication. (PD)

  14. Communication Strategies

    OpenAIRE

    Strate, Simon Wolter; Loznica, Javor; Nærland, Kristoffer; Skipper, Mads Christian; Jensen, Charlotte Haagen

    2013-01-01

    This project focuses on the oil company, Shell, and their way of conducting themselves on social media sites, specifically Facebook and twitter. We establish this by using social media theory, and corporate campaign theories, and applying these to the content that Shell puts out on these particular social media sites. Furthermore, the project establishes a critical evaluation of the weight and presence of social media within modern corporate communication and issue management.

  15. Quantum Communication

    OpenAIRE

    Gisin, Nicolas; Thew, Rob

    2007-01-01

    Quantum communication, and indeed quantum information in general, has changed the way we think about quantum physics. In 1984 and 1991, the first protocol for quantum cryptography and the first application of quantum non-locality, respectively, attracted a diverse field of researchers in theoretical and experimental physics, mathematics and computer science. Since then we have seen a fundamental shift in how we understand information when it is encoded in quantum systems. We review the curren...

  16. Ion-Regulated Allosteric Binding of Fullerenes (C-60 and C-70) by Tetrathiafulvalene-Calix[4]pyrroles

    DEFF Research Database (Denmark)

    Davis, C. M.; Lim, J. M.; Larsen, K. R.;

    2014-01-01

    The effect of ionic species on the binding of fullerenes (C-60 and C-70) by tetrathiafulvalene-calix[4]pyrrole (TTF-C4P) receptors and the nature of the resulting supramolecular complexes (TTF-C4P + fullerene + halide anion + tetraalkylammonium cation) was studied in the solid state through single...... the C4P in a ball-and-socket binding mode. The interactions between the TTF-C4P receptors and the fullerene guests are highly influenced by both the nature of halide anions and their counter tetraalkylammonium cations. Three halides (F-, Cl-, and Br-) were studied. All three potentiate the binding of...... the two test fullerenes by inducing a conformational change from the 1,3-alternate to the cone conformer of the TTF-C4Ps, thus acting as positive heterotropic allosteric effectors. For a particular halide anion, the choice of tetraalkylammonium salts serves to modulate the strength of the TTF-C4P...

  17. Elucidation of the ATP7B N-domain Mg2+-ATP coordination site and its allosteric regulation.

    Directory of Open Access Journals (Sweden)

    Claude Hercend

    Full Text Available The diagnostic of orphan genetic disease is often a puzzling task as less attention is paid to the elucidation of the pathophysiology of these rare disorders at the molecular level. We present here a multidisciplinary approach using molecular modeling tools and surface plasmonic resonance to study the function of the ATP7B protein, which is impaired in the Wilson disease. Experimentally validated in silico models allow the elucidation in the Nucleotide binding domain (N-domain of the Mg(2+-ATP coordination site and answer to the controversial role of the Mg(2+ ion in the nucleotide binding process. The analysis of protein motions revealed a substantial effect on a long flexible loop branched to the N-domain protein core. We demonstrated the capacity of the loop to disrupt the interaction between Mg(2+-ATP complex and the N-domain and propose a role for this loop in the allosteric regulation of the nucleotide binding process.

  18. Thermodynamic Characterization of New Positive Allosteric Modulators Binding to the Glutamate Receptor A2 Ligand-Binding Domain

    DEFF Research Database (Denmark)

    Nørholm, Ann-Beth; Francotte, Pierre; Goffin, Eric; Botez, Iuliana; Danober, Laurence; Lestage, Pierre; Pirotte, Bernard; Kastrup, Jette Sandholm Jensen; Olsen, Lars; Oostenbrink, Chris

    2014-01-01

    5a (5-F) and 5b (6-F) are entropy driven. For 5d (8-F), both quantities were equal in size. Thermodynamic integration (TI) and one-step perturbation (OSP) were used to calculate the relative binding affinity of the modulators. The OSP calculations had a higher predictive power than those from TI......Positive allosteric modulation of the ionotropic glutamate receptor GluA2 presents a potential treatment of cognitive disorders, for example, Alzheimer's disease. In the present study, we describe the synthesis, pharmacology, and thermodynamic studies of a series of monofluoro-substituted 3......,4-dihydro-2H-1,2,4-benzothiadiazine 1,1-dioxides. Measurements of ligand binding by isothermal titration calorimetry (ITC) showed similar binding affinities for the modulator series at the GluA2 LBD but differences in the thermodynamic driving forces. Binding of 5c (7-F) and 6 (no-F) is enthalpy driven, and...

  19. Docking of noncompetitive inhibitors into dengue virus type 2 protease: understanding the interactions with allosteric binding sites.

    Science.gov (United States)

    Othman, Rozana; Kiat, Tan Siew; Khalid, Norzulaani; Yusof, Rohana; Newhouse, E Irene; Newhouse, James S; Alam, Masqudul; Rahman, Noorsaadah Abdul

    2008-08-01

    A group of flavanones and their chalcones, isolated from Boesenbergia rotunda L., were previously reported to show varying degrees of noncompetitive inhibitory activities toward Dengue virus type 2 (Den2) protease. Results obtained from automated docking studies are in agreement with experimental data in which the ligands were shown to bind to sites other than the active site of the protease. The calculated K(i) values are very small, indicating that the ligands bind quite well to the allosteric binding site. Greater inhibition by pinostrobin, compared to the other compounds, can be explained by H-bonding interaction with the backbone carbonyl of Lys74, which is bonded to Asp75 (one of the catalytic triad residues). In addition, structure-activity relationship analysis yields structural information that may be useful for designing more effective therapeutic drugs against dengue virus infections. PMID:18656912

  20. In vitro and in vivo characterization of a novel negative allosteric modulator of neuronal nAChRs

    OpenAIRE

    Abdrakhmanova, Galya R.; Blough, Bruce E.; Nesloney, Carey; Navarro, Hernán A.; Damaj, M. Imad; Carroll, F. Ivy

    2010-01-01

    In this study, we compared the in vitro and in vivo neuronal nicotinic acetylcholine receptor (nAChR) properties of 1,2,3,3a,4,8b-hexahydro-2-benzyl-6-N,N-dimethylamino-1-methylindeno[1,2,-b]pyrrole (HDMP, 4) to that of negative allosteric modulator (NAM), PCP. Patch-clamp experiments showed that HDMP exhibited an inhibitory functional activity at α7 nAChRs with an IC50 of 0.07 μM, and was 357- and 414-fold less potent at α4β2 and α3β4 nAChRs, with IC50s of 25.1 and 29.0 μM, respectively. Con...

  1. Uranium occurence in nature: Geophysical prospecting, and its occurence in Syria

    International Nuclear Information System (INIS)

    A general idea about naturaly occured uranium minerals such as uranite, pechblende, carnotite, coffinit, and bronnerit is given. At the same time, different geophysical methods and detecting devices applied for uranium exploration have been demonstrated. Investigations and studies carried out in Syria point to a uranium content of 100 ppm in the exploited Syrian phosphorite. 1 fig., 1 tab

  2. Role of a novel PH-kinase domain interface in PKB/Akt regulation: structural mechanism for allosteric inhibition.

    Directory of Open Access Journals (Sweden)

    Véronique Calleja

    2009-01-01

    Full Text Available Protein kinase B (PKB/Akt belongs to the AGC superfamily of related serine/threonine protein kinases. It is a key regulator downstream of various growth factors and hormones and is involved in malignant transformation and chemo-resistance. Full-length PKB protein has not been crystallised, thus studying the molecular mechanisms that are involved in its regulation in relation to its structure have not been simple. Recently, the dynamics between the inactive and active conformer at the molecular level have been described. The maintenance of PKB's inactive state via the interaction of the PH and kinase domains prevents its activation loop to be phosphorylated by its upstream activator, phosphoinositide-dependent protein kinase-1 (PDK1. By using a multidisciplinary approach including molecular modelling, classical biochemical assays, and Förster resonance energy transfer (FRET/two-photon fluorescence lifetime imaging microscopy (FLIM, a detailed model depicting the interaction between the different domains of PKB in its inactive conformation was demonstrated. These findings in turn clarified the molecular mechanism of PKB inhibition by AKT inhibitor VIII (a specific allosteric inhibitor and illustrated at the molecular level its selectivity towards different PKB isoforms. Furthermore, these findings allude to the possible function of the C-terminus in sustaining the inactive conformer of PKB. This study presents essential insights into the quaternary structure of PKB in its inactive conformation. An understanding of PKB structure in relation to its function is critical for elucidating its mode of activation and discovering how to modulate its activity. The molecular mechanism of inhibition of PKB activation by the specific drug AKT inhibitor VIII has critical implications for determining the mechanism of inhibition of other allosteric inhibitors and for opening up opportunities for the design of new generations of modulator drugs.

  3. The Ascaris suum nicotinic receptor, ACR-16, as a drug target: Four novel negative allosteric modulators from virtual screening.

    Science.gov (United States)

    Zheng, Fudan; Robertson, Alan P; Abongwa, Melanie; Yu, Edward W; Martin, Richard J

    2016-04-01

    Soil-transmitted helminth infections in humans and livestock cause significant debility, reduced productivity and economic losses globally. There are a limited number of effective anthelmintic drugs available for treating helminths infections, and their frequent use has led to the development of resistance in many parasite species. There is an urgent need for novel therapeutic drugs for treating these parasites. We have chosen the ACR-16 nicotinic acetylcholine receptor of Ascaris suum (Asu-ACR-16), as a drug target and have developed three-dimensional models of this transmembrane protein receptor to facilitate the search for new bioactive compounds. Using the human α7 nAChR chimeras and Torpedo marmorata nAChR for homology modeling, we defined orthosteric and allosteric binding sites on the Asu-ACR-16 receptor for virtual screening. We identified four ligands that bind to sites on Asu-ACR-16 and tested their activity using electrophysiological recording from Asu-ACR-16 receptors expressed in Xenopus oocytes. The four ligands were acetylcholine inhibitors (SB-277011-A, IC50, 3.12 ± 1.29 μM; (+)-butaclamol Cl, IC50, 9.85 ± 2.37 μM; fmoc-1, IC50, 10.00 ± 1.38 μM; fmoc-2, IC50, 16.67 ± 1.95 μM) that behaved like negative allosteric modulators. Our work illustrates a structure-based in silico screening method for seeking anthelmintic hits, which can then be tested electrophysiologically for further characterization. PMID:27054065

  4. VU0477573: Partial Negative Allosteric Modulator of the Subtype 5 Metabotropic Glutamate Receptor with In Vivo Efficacy.

    Science.gov (United States)

    Nickols, Hilary Highfield; Yuh, Joannes P; Gregory, Karen J; Morrison, Ryan D; Bates, Brittney S; Stauffer, Shaun R; Emmitte, Kyle A; Bubser, Michael; Peng, Weimin; Nedelcovych, Michael T; Thompson, Analisa; Lv, Xiaohui; Xiang, Zixiu; Daniels, J Scott; Niswender, Colleen M; Lindsley, Craig W; Jones, Carrie K; Conn, P Jeffrey

    2016-01-01

    Negative allosteric modulators (NAMs) of metabotropic glutamate receptor subtype 5 (mGlu5) have potential applications in the treatment of fragile X syndrome, levodopa-induced dyskinesia in Parkinson disease, Alzheimer disease, addiction, and anxiety; however, clinical and preclinical studies raise concerns that complete blockade of mGlu5 and inverse agonist activity of current mGlu5 NAMs contribute to adverse effects that limit the therapeutic use of these compounds. We report the discovery and characterization of a novel mGlu5 NAM, N,N-diethyl-5-((3-fluorophenyl)ethynyl)picolinamide (VU0477573) that binds to the same allosteric site as the prototypical mGlu5 NAM MPEP but displays weak negative cooperativity. Because of this weak cooperativity, VU0477573 acts as a "partial NAM" so that full occupancy of the MPEP site does not completely inhibit maximal effects of mGlu5 agonists on intracellular calcium mobilization, inositol phosphate (IP) accumulation, or inhibition of synaptic transmission at the hippocampal Schaffer collateral-CA1 synapse. Unlike previous mGlu5 NAMs, VU0477573 displays no inverse agonist activity assessed using measures of effects on basal [(3)H]inositol phosphate (IP) accumulation. VU0477573 acts as a full NAM when measuring effects on mGlu5-mediated extracellular signal-related kinases 1/2 phosphorylation, which may indicate functional bias. VU0477573 exhibits an excellent pharmacokinetic profile and good brain penetration in rodents and provides dose-dependent full mGlu5 occupancy in the central nervous system (CNS) with systemic administration. Interestingly, VU0477573 shows robust efficacy, comparable to the mGlu5 NAM MTEP, in models of anxiolytic activity at doses that provide full CNS occupancy of mGlu5 and demonstrate an excellent CNS occupancy-efficacy relationship. VU0477573 provides an exciting new tool to investigate the efficacy of partial NAMs in animal models. PMID:26503377

  5. Quantum Communication Complexity

    OpenAIRE

    Klauck, Hartmut

    2000-01-01

    This paper surveys the field of quantum communication complexity. Some interesting recent results are collected concerning relations to classical communication, lower bound methods, one-way communication, and applications of quantum communication complexity.

  6. Communication, Technology, Temporality

    Directory of Open Access Journals (Sweden)

    Mark A. Martinez

    2012-08-01

    possibilities within this temporality. In attempting to think past a merely human scale of time, my project interfaces with other non-totalizing, anti-anthropocentric philosophies, but begins from modernist and humanist understandings of temporality as opposed to subjectivity. Methodologically, my theory of temporality provides a shift in historical narrative, one that eschews famous inventors, threads of technological or epistemological progress, or other teleological constructions. Epistemologically, this temporality indicates that mediation is an event that occurs among various types of organisms of multiple temporalities. This allows precise interrogation of human notions inflected with time: duration, suspension, desire, fear, and imagination. Ethically, scaling time beyond the human gives a novel form of alterity articulated as the different ways in which we use time to capture the other within theories of communication and history.

  7. COMMUNICATION – PICTURE WITHOUT WORDS

    Directory of Open Access Journals (Sweden)

    Corina MATEI GHERMAN

    2015-12-01

    Full Text Available Communication occurs when a transmitter transmits to a transmitter, information or messages related to a specific subject (product, service, idea, etc. for the purpose of this receptor messages, make it known to awaken a certain emotional reaction. Communication through images offer multiple advantages over media communication, it uses the most modern means of collection, processing and transmission of the image with which beneficiaries can build brand company / person using marketing techniques and gaining important benefits in terms promoting products or services. Image is an important communication support, which should give it considerable attention generation, transmission and its reception by a coded language, well structured and efficient. Method and methodology – for the study we used the literature in the field and direct observation. The results were processed by methods of literature and practical examples taking place in an unstable competitive environment.

  8. Interdisciplinary Communication

    Directory of Open Access Journals (Sweden)

    Nagib Callaos

    2013-12-01

    Full Text Available Communication is fundamental in scientific practice and an integral part of academic work. The practice of communication cannot be neglected by those who are trying to advance scientific research. Effective means should continuously be identified in order to open channels of communication within and among disciplines, among scientists and between scientists and the general public.[1]The increasing importance of interdisciplinary communication has been pointed out by an increasing number of researchers and scholars, as well as in conferences and roundtables on the subject. Some authors even estimate that "interdisciplinary study represents the future of the university."[2] Since interdisciplinary study is "the most underthought critical, pedagogical and institutional concept in modern academy"[3] it is important to think and reflect, and even do some research, on this concept or notion. Research and practice based reflections with regards to this issue are important especially because the increasing complexity and proliferation of scientific research is generating countless specialties, sub-specialties and sub-sub-specialties, with their respective special languages; which were "created for discrete local areas of research based upon the disconnected branches of science."[4] On the other hand, scientific, technical and societal problems are requiring multi- or inter-disciplinary consideration. Consequently, interdisciplinary communication channels are being needed with urgency, and scientific research should be integrated, not just in the context of its discipline, but also in the context of related disciplines. Much more reflection and research should be done on this issue. Research on adequate research integration and communication is urgently required, i.e. meta-research efforts should be done in order to relate research results in an adequate and more useful way. This meta-research effort might be done in the context of each particular

  9. Risk communication

    International Nuclear Information System (INIS)

    The study on risk communication identifies the deficiencies concerning empirical and theoretical knowledge on objective radiation hazards of the acting personnel (managers, politicians, jurists, etc.) in administrations, governmental agencies, and business management. This is especially problematic with respect to emergency planning and estimations concerning the public behavior. The incident/accident information in Germany is discussed based on the legislative regulations revealing the controversial perception between industry, legislative and public interest. Further topics include the meandering of the modern safety semantics and the public opinion concerning catastrophic risk.

  10. Intercultural Communication Ethics and Communication Competence%Intercultural Communication Ethics and Communication Competence

    Institute of Scientific and Technical Information of China (English)

    时婷洁

    2012-01-01

    This paper investigates intercultural communication ethics is a vital element to promote intercultural communication competence. Firstly, it defines the concept of intercultural communication ethics; Secondly, it illustrates the relation between ethics and the key point of intercultural communication competence; and finally addresses how intercultural communication ethics can improve intercultural communication competence.

  11. Submarine Communications .

    Directory of Open Access Journals (Sweden)

    H.B. Singh

    1993-01-01

    Full Text Available Submarines operating in deep water are virtually cut off from the outer world. It becomes very important and essential to convey survivable and critical information to the submarine during the time it operates under water. Conventional means of radio communication do not serve any useful purpose as the higher frequencies get attenuated very sharply in sea water. At VLF band, which is presently being used by most of the world Navies, signal can penetrate only upto 8-10 m of depth. This depth is not sufficient under hostile environment. ELF is another band where listening depth is around 100 m but data rate is very low. This paper summarizes the various means of communication used to send messages to submarine while cruising at various depths. It seems that in the near future blue-green laser is going to be the vital means of sending large information to a submarine operating much deeper (500-700 m with unrestricted speed.

  12. 'Culture' and 'communication' in intercultural communication.

    OpenAIRE

    Durant, Alan; Shepherd, Ifan D. H.

    2009-01-01

    Two major influences on contemporary societies dictate that diffusion and hybridization of communicative norms will be an increasingly significant feature of our communication landscape: Transnational population flows; and the impact of mediated communication, including by means of the Internet. This study explores implications of different ways of viewing the 'cultural' and 'communication' dimensions of intercultural communication in such volatile circumstances. It considers the risk of repr...

  13. Data communications and computer communications network

    International Nuclear Information System (INIS)

    This textbook is composed of twelve chapters, which are communication network introduction, foundation of data communication, data link control, circuit switching system, packet switching system, multiple access communication system, protocol and architecture, LAN, MAN communication network, integrated service digital network, internet and Asymmetric digital subscriber Line and Wireless Local Loop. Each chapter has the introduction of the technique, structure, function and practice problems. It also has the appendix on electricity and communication standards organization, characteristic table and glossary.

  14. Creativity in clinical communication: from communication skills to skilled communication.

    Science.gov (United States)

    Salmon, Peter; Young, Bridget

    2011-03-01

    Medical Education 2011: 45: 217-226 Objectives  The view that training in communication skills produces skilled communication is sometimes criticised by those who argue that communication is individual and intuitive. We therefore examine the validity of the concept of communication as a skill and identify alternative principles to underpin future development of this field. Methods  We critically examine research evidence about the nature of clinical communication, and draw from theory and evidence concerning education and evaluation, particularly in creative disciplines. Results  Skilled communication cannot be fully described using the concept of communication skills. Attempts to do so risk constraining and distorting pedagogical development in communication. Current education practice often masks the difficulties with the concept by introducing subjectivity into the definition and assessment of skills. As all clinical situations differ to some extent, clinical communication is inherently creative. Because it is rarely possible to attribute specific effects to specific elements of communication, communication needs to be taught and evaluated holistically. Conclusions  For communication teaching to be pedagogically and clinically valid in supporting the inherent creativity of clinical communication, it will need to draw from education theory and practice that have been developed in explicitly creative disciplines. PMID:21299597

  15. Crisis Communication

    International Nuclear Information System (INIS)

    The author discusses how one of the strongest examples of how destructive poor crisis communications can be the Three Mile Island accident of March 1979. This was an event that was minimal in its physical effects on the public and environment beyond the walls of that nuclear power plant. However, the emotional trauma on the local public, the economic impact on area businesses and property owners, and the long term impact on the entire nuclear utility industry were great. Approximately 80,000 people as far as 15 miles from the plant evacuated over a weekend. There have been no new orders for nuclear plants and many cancellations since the event 10 years ago. This paper presents an analysis of the accident at Three Mile Island

  16. Individualized Communications

    Science.gov (United States)

    1997-01-01

    IntelliWeb and IntelliPrint, products from MicroMass Communications, utilize C Language Integrated Production System (CLIPS), a development and delivery expert systems tool developed at Johnson Space Center. IntelliWeb delivers personalized messages by dynamically creating single web pages or entire web sites based on information provided by each website visitor. IntelliPrint is a product designed to create tailored, individualized messages via printed media. The software uses proprietary technology to generate printed messages that are personally relevant and tailored to meet each individual's needs. Intelliprint is in use in many operations including Brystol-Myers Squibb's personalized newsletter, "Living at Your Best," geared to each recipient based on a health and lifestyle survey taken earlier; and SmithKline Beecham's "Nicorette Committed Quitters Program," in which customized motivational materials support participants in their attempt to quit smoking.

  17. Communicative Musicality

    DEFF Research Database (Denmark)

    Holck, Ulla

    2010-01-01

    took place in his laboratory at Edinburgh University, and showed how the mother joined her daughter with imitative sounds that were modulated emotionally to invite the infant’s coos and to acknowledge them in shared time. Seventeen years later, in 1996, in the Psychology Department at the very same....... With their new book Communicative Musicality – Exploring the Basis of Human Companionship, Malloch and Trevarthen have elaborated extensively on the concept by inviting 35 authors from a very broad spectrum of research areas, such as musicology, music therapy, dance therapy, psychology, child and adolescent...... •Musicality in childhood learning •Musicality in performance When talking of ‘musicality’ the editors point to the innate human abilities that make music production and appreciation possible. They give the following definition of musicality, which can be seen as the essence of the book’s idea: “We define...

  18. A combination of temsirolimus, an allosteric mTOR inhibitor, with clofarabine as a new therapeutic option for patients with acute myeloid leukemia

    OpenAIRE

    Chiarini, Francesca; Lonetti, Annalisa; Teti, Gabriella; Orsini, Ester; Bressanin, Daniela; Cappellini, Alessandra; Ricci, Francesca; Tazzari, Pier Luigi; Ognibene, Andrea; Falconi, Mirella; Pagliaro, Pasqualepaolo; Iacobucci, Ilaria; Martinelli, Giovanni; Amadori, Sergio; McCubrey, James A.

    2012-01-01

    Signaling through the phosphatidylinositol 3-kinase (PI3K) pathway and its downstream effectors, Akt and mechanistic target of rapamycin (mTOR), is aberrantly activated in acute myeloid leukemia (AML) patients, where it contributes to leukemic cell proliferation, survival, and drug-resistance. Thus, inhibiting mTOR signaling in AML blasts could enhance their sensitivity to cytotoxic agents. Preclinical data also suggest that allosteric mTOR inhibition with rapamycin impaired leukemia initiati...

  19. The Nature of Allosteric Inhibition in Glutamate Racemase: discovery and characterization of a cryptic inhibitory pocket using atomistic MD simulations and pKa calculations

    OpenAIRE

    Whalen, Katie L.; Tussey, Kenneth B.; Blanke, Steven R.; Spies, M. Ashley

    2011-01-01

    Enzyme inhibition via allostery, in which the ligand binds remotely from the active site, is a poorly understood phenomenon, and represents a significant challenge to structure-based drug design. Dipicolinic acid (DPA), a major component of Bacillus spores, is shown to inhibit glutamate racemase from Bacillus anthracis, a monosubstrate/monoproduct enzyme, in a novel allosteric fashion. Glutamate racemase has long been considered an important drug target for its integral role in bacterial cell...

  20. Effects of the dopamine D2 allosteric modulator, PAOPA, on the expression of GRK2, arrestin-3, ERK1/2, and on receptor internalization.

    Directory of Open Access Journals (Sweden)

    Dipannita Basu

    Full Text Available The activity of G protein-coupled receptors (GPCRs is intricately regulated by a range of intracellular proteins, including G protein-coupled kinases (GRKs and arrestins. Understanding the effects of ligands on these signaling pathways could provide insights into disease pathophysiologies and treatment. The dopamine D2 receptor is a GPCR strongly implicated in the pathophysiology of a range of neurological and neuropsychiatric disorders, particularly schizophrenia. Previous studies from our lab have shown the preclinical efficacy of a novel allosteric drug, 3(R-[(2(S-pyrrolidinylcarbonylamino]-2-oxo-1-pyrrolidineacetamide (PAOPA, in attenuating schizophrenia-like behavioural abnormalities in rodent models of the disease. As an allosteric modulator, PAOPA binds to a site on the D2 receptor, which is distinct from the endogenous ligand-binding site, in order to modulate the binding of the D2 receptor ligand, dopamine. The exact signaling pathways affected by this allosteric modulator are currently unknown. The objectives of this study were to decipher the in vivo effects, in rats, of chronic PAOPA administration on D2 receptor regulatory and downstream molecules, including GRK2, arrestin-3 and extracellular receptor kinase (ERK 1/2. Additionally, an in vitro cellular model was also used to study PAOPA's effects on D2 receptor internalization. Results from western immunoblots showed that chronic PAOPA treatment increased the striatal expression of GRK2 by 41%, arrestin-3 by 34%, phospho-ERK1 by 51% and phospho-ERK2 by 36%. Results also showed that the addition of PAOPA to agonist treatment in cells increased D2 receptor internalization by 33%. This study provides the foundational evidence of putative signaling pathways, and changes in receptor localization, affected by treatment with PAOPA. It improves our understanding on the diverse mechanisms of action of allosteric modulators, while advancing PAOPA's development into a novel drug for the

  1. Allosteric inhibition enhances the efficacy of ABL kinase inhibitors to target unmutated BCR-ABL and BCR-ABL-T315I

    Directory of Open Access Journals (Sweden)

    Mian Afsar

    2012-09-01

    Full Text Available Abstract Background Chronic myelogenous leukemia (CML and Philadelphia chromosome-positive (Ph+ acute lymphatic leukemia (Ph + ALL are caused by the t(9;22, which fuses BCR to ABL resulting in deregulated ABL-tyrosine kinase activity. The constitutively activated BCR/ABL-kinase “escapes” the auto-inhibition mechanisms of c-ABL, such as allosteric inhibition. The ABL-kinase inhibitors (AKIs Imatinib, Nilotinib or Dasatinib, which target the ATP-binding site, are effective in Ph + leukemia. Another molecular therapy approach targeting BCR/ABL restores allosteric inhibition. Given the fact that all AKIs fail to inhibit BCR/ABL harboring the ‘gatekeeper’ mutation T315I, we investigated the effects of AKIs in combination with the allosteric inhibitor GNF2 in Ph + leukemia. Methods The efficacy of this approach on the leukemogenic potential of BCR/ABL was studied in Ba/F3 cells, primary murine bone marrow cells, and untransformed Rat-1 fibroblasts expressing BCR/ABL or BCR/ABL-T315I as well as in patient-derived long-term cultures (PDLTC from Ph + ALL-patients. Results Here, we show that GNF-2 increased the effects of AKIs on unmutated BCR/ABL. Interestingly, the combination of Dasatinib and GNF-2 overcame resistance of BCR/ABL-T315I in all models used in a synergistic manner. Conclusions Our observations establish a new approach for the molecular targeting of BCR/ABL and its resistant mutants using a combination of AKIs and allosteric inhibitors.

  2. Hydrogen/Deuterium Exchange Kinetics Demonstrate Long Range Allosteric Effects of Thumb Site 2 Inhibitors of Hepatitis C Viral RNA-dependent RNA Polymerase.

    Science.gov (United States)

    Deredge, Daniel; Li, Jiawen; Johnson, Kenneth A; Wintrode, Patrick L

    2016-05-01

    New nonnucleoside analogs are being developed as part of a multi-drug regimen to treat hepatitis C viral infections. Particularly promising are inhibitors that bind to the surface of the thumb domain of the viral RNA-dependent RNA polymerase (NS5B). Numerous crystal structures have been solved showing small molecule non-nucleoside inhibitors bound to the hepatitis C viral polymerase, but these structures alone do not define the mechanism of inhibition. Our prior kinetic analysis showed that nonnucleoside inhibitors binding to thumb site-2 (NNI2) do not block initiation or elongation of RNA synthesis; rather, they block the transition from the initiation to elongation, which is thought to proceed with significant structural rearrangement of the enzyme-RNA complex. Here we have mapped the effect of three NNI2 inhibitors on the conformational dynamics of the enzyme using hydrogen/deuterium exchange kinetics. All three inhibitors rigidify an extensive allosteric network extending >40 Å from the binding site, thus providing a structural rationale for the observed disruption of the transition from distributive initiation to processive elongation. The two more potent inhibitors also suppress slow cooperative unfolding in the fingers extension-thumb interface and primer grip, which may contribute their stronger inhibition. These results establish that NNI2 inhibitors act through long range allosteric effects, reveal important conformational changes underlying normal polymerase function, and point the way to the design of more effective allosteric inhibitors that exploit this new information. PMID:27006396

  3. Fiber-optic communication systems

    CERN Document Server

    Agrawal, Govind P

    2010-01-01

    This book provides a comprehensive account of fiber-optic communication systems. The 3rd edition of this book is used worldwide as a textbook in many universities. This 4th edition incorporates recent advances that have occurred, in particular two new chapters. One deals with the advanced modulation formats (such as DPSK, QPSK, and QAM) that are increasingly being used for improving spectral efficiency of WDM lightwave systems. The second chapter focuses on new techniques such as all-optical regeneration that are under development and likely to be used in future communication systems. All othe

  4. Millisecond dynamics in the allosteric enzyme imidazole glycerol phosphate synthase (IGPS) from Thermotoga maritima

    International Nuclear Information System (INIS)

    IGPS is a 51 kDa heterodimeric enzyme comprised of two proteins, HisH and HisF, that catalyze the hydrolysis of glutamine to produce NH3 in the HisH active site and the cyclization of ammonia with N'- [(5'-phosphoribulosyl)formimino] -5-aminoimidazole-4-carboxamide-ribonucleotide (PRFAR) in HisF to produce imidazole glycerol phosphate (IGP) and 5-aminoimidazole-4-carboxamide ribotide (AICAR). Binding of PRFAR and IGP stimulates glutaminase activity in the HisH enzyme over 5,000 and 100-fold, respectively, despite the active sites being >25 A apart. The details of this long-range protein communication process were investigated by solution NMR spectroscopy and CPMG relaxation dispersion experiments. Formation of the heterodimer enzyme results in a reduction in millisecond motions in HisF that extend throughout the protein. Binding of lGP results in an increase in protein-wide millisecond dynamics evidenced as severe NMR line broadening and elevated Rex values. Together, these data demonstrate a grouping of flexible residues that link the HisF active site with the protein interface to which HisH binds and provide a model for the path of communication between the IGPS active sites

  5. Insecticidal 3-benzamido-N-phenylbenzamides specifically bind with high affinity to a novel allosteric site in housefly GABA receptors.

    Science.gov (United States)

    Ozoe, Yoshihisa; Kita, Tomo; Ozoe, Fumiyo; Nakao, Toshifumi; Sato, Kazuyuki; Hirase, Kangetsu

    2013-11-01

    γ-Aminobutyric acid (GABA) receptors (GABARs) are an important target for existing insecticides such as fiproles. These insecticides act as noncompetitive antagonists (channel blockers) for insect GABARs by binding to a site within the intrinsic channel of the GABAR. Recently, a novel class of insecticides, 3-benzamido-N-phenylbenzamides (BPBs), was shown to inhibit GABARs by binding to a site distinct from the site for fiproles. We examined the binding site of BPBs in the adult housefly by means of radioligand-binding and electrophysiological experiments. 3-Benzamido-N-(2,6-dimethyl-4-perfluoroisopropylphenyl)-2-fluorobenzamide (BPB 1) (the N-demethyl BPB) was a partial, but potent, inhibitor of [(3)H]4'-ethynyl-4-n-propylbicycloorthobenzoate (GABA channel blocker) binding to housefly head membranes, whereas the 3-(N-methyl)benzamido congener (the N-methyl BPB) had low or little activity. A total of 15 BPB analogs were tested for their abilities to inhibit [(3)H]BPB 1 binding to the head membranes. The N-demethyl analogs, known to be highly effective insecticides, potently inhibited the [(3)H]BPB 1 binding, but the N-methyl analogs did not even though they, too, are considered highly effective. [(3)H]BPB 1 equally bound to the head membranes from wild-type and dieldrin-resistant (rdl mutant) houseflies. GABA allosterically inhibited [(3)H]BPB 1 binding. By contrast, channel blocker-type antagonists enhanced [(3)H]BPB 1 binding to housefly head membranes by increasing the affinity of BPB 1. Antiparasitic macrolides, such as ivermectin B1a, were potent inhibitors of [(3)H]BPB 1 binding. BPB 1 inhibited GABA-induced currents in housefly GABARs expressed in Xenopus oocytes, whereas it failed to inhibit l-glutamate-induced currents in inhibitory l-glutamate receptors. Overall, these findings indicate that BPBs act at a novel allosteric site that is different from the site for channel blocker-type antagonists and that is probably overlapped with the site for macrolides

  6. Treatment for Co-Occurring Attention Deficit/Hyperactivity Disorder and Autism Spectrum Disorder

    OpenAIRE

    Davis, Naomi Ornstein; Kollins, Scott H.

    2012-01-01

    Interest in the co-occurrence of attention deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) has grown in the last decade. Research on clinical populations supports the frequent co-occurrence of ADHD traits (e.g., hyperactivity) in individuals with ASD and ASD traits (e.g., social communication deficits) in individuals with ADHD. Similar trends in co-occurring traits have been observed in population-based samples, as well as family and genetic studies of affected indivi...

  7. Airborne wireless communication systems, airborne communication methods, and communication methods

    Science.gov (United States)

    Deaton, Juan D.; Schmitt, Michael J.; Jones, Warren F.

    2011-12-13

    An airborne wireless communication system includes circuitry configured to access information describing a configuration of a terrestrial wireless communication base station that has become disabled. The terrestrial base station is configured to implement wireless communication between wireless devices located within a geographical area and a network when the terrestrial base station is not disabled. The circuitry is further configured, based on the information, to configure the airborne station to have the configuration of the terrestrial base station. An airborne communication method includes answering a 911 call from a terrestrial cellular wireless phone using an airborne wireless communication system.

  8. Business Communication Strategies

    OpenAIRE

    Lavinia Hulea

    2005-01-01

    General communication processes rely on messages implying contents, communication channels, a receiver and clear objectives. Once accepting the importance of defining objectives, three strategies, narrative, implicative, and decisional, seem to be specific for most business communications. While narrative business communications convey information with a view of simply transmitting information and depend on accuracy, complexity, and clarity, implicative business communications convey informat...

  9. Using Codes to Communicate

    Institute of Scientific and Technical Information of China (English)

    李媛

    2005-01-01

    @@ When we communicate, we want our messages and meanings to be understood. The difficulty is that much of what we do when we communicate comes from our subjective culture. In communications, when we share culture, we share meanings,and when we communicate, we exchange meanings. When we prepare to communicate with strangers from other cultures, we usually begin by learning a language.

  10. DIORAMA Communications

    Energy Technology Data Exchange (ETDEWEB)

    Galassi, Mark C. [Los Alamos National Laboratory

    2016-05-24

    Diorama is written as a collection of modules that can run in separate threads or in separate processes. This defines a clear interface between the modules and also allows concurrent processing of different parts of the pipeline. The pipeline is determined by a description in a scenario file[Norman and Tornga, 2012, Tornga and Norman, 2014]. The scenario manager parses the XML scenario and sets up the sequence of modules which will generate an event, propagate the signal to a set of sensors, and then run processing modules on the results provided by those sensor simulations. During a run a variety of “observer” and “processor” modules can be invoked to do interim analysis of results. Observers do not modify the simulation results, while processors may affect the final result. At the end of a run results are collated and final reports are put out. A detailed description of the scenario file and how it puts together a simulation are given in [Tornga and Norman, 2014]. The processing pipeline and how to program it with the Diorama API is described in Tornga et al. [2015] and Tornga and Wakeford [2015]. In this report I describe the communications infrastructure that is used.

  11. COMMUNICATIONS GROUP

    CERN Multimedia

    L. Taylor

    2011-01-01

    Communications Infrastructure The 55 CMS Centres worldwide are well used by physicists working on remote CMS shifts, Computing operations, data quality monitoring, data analysis and outreach. The CMS Centre@CERN in Meyrin is particularly busy at the moment, hosting about 50 physicists taking part in the heavy-ion data-taking and analysis. Three new CMS meeting room will be equipped for videoconferencing in early 2012: 40/5B-08, 42/R-031, and 28/S-029. The CMS-TV service showing LHC Page 1, CMS Page 1, etc. (http://cmsdoc.cern.ch/cmscc/projector/index.jsp) is now also available for mobile devices: http://cern.ch/mcmstv. Figure 12: Screenshots of CMS-TV for mobile devices Information Systems CMS has a new web site: (http://cern.ch/cms) using a modern web Content Management System to ensure content and links are managed and updated easily and coherently. It covers all CMS sub-projects and groups, replacing the iCMS internal pages. It also incorporates the existing CMS public web site (http:/...

  12. COMMUNICATIONS GROUP

    CERN Multimedia

    L. Taylor

    2012-01-01

      Outreach and Education We are fortunate that our research has captured the public imagination, even though this inevitably puts us under the global media spotlight, as we saw with the Higgs seminar at CERN in December, which had 110,000 distinct webcast viewers. The media interest was huge with 71 media organisations registering to come to CERN to cover the Higgs seminar, which was followed by a press briefing with the DG and Spokespersons. This event resulted in about 2,000 generally positive stories in the global media. For this seminar, the CMS Communications Group prepared up-to-date news and public material, including links to the CMS results, animations and event displays [http://cern.ch/go/Ch8thttp://cern.ch/go/Ch8t]. There were 44,000 page-views on the CMS public website, with the Higgs news article being by far the most popular item. CMS event displays from iSpy are fast becoming the iconic media images, featuring on numerous major news outlets (BBC, CNN, MSN...) as well as in the sci...

  13. Heterosocial Communicative Behavior and Communication Apprehension.

    Science.gov (United States)

    Prisbell, Marshall

    A study investigated the relationship between levels of communication apprehension (high or low) and eight heterosocial (between sexes) communicative behavior variables--conditioned anxiety, heterosocial skills, heterosocial apprehension, activity, proximity, heterosocial expectations, physical attractiveness, and heterosocial importance. In…

  14. Communication and Alzheimer's

    Science.gov (United States)

    ... We will not sell or share your name. Communication and Alzheimer's Tweet Bookmark this page | Email | Print ... Best ways for you to communicate Changes in communication In addition to changes in the brain caused ...

  15. Programming with Quantum Communication

    OpenAIRE

    Tafliovich, Anya; Hehner, Eric C. R.

    2009-01-01

    This work develops a formal framework for specifying, implementing, and analysing quantum communication protocols. We provide tools for developing simple proofs and analysing programs which involve communication, both via quantum channels and exhibiting the LOCC (local operations, classical communication) paradigm.

  16. European Communication Report 2008

    OpenAIRE

    Beurer-Züllig, Bettina; Fieseler, Christian; Meckel, Miriam

    2008-01-01

    A survey by the European Association of Communication Directors (EACD) and the Institute of Media and Communications Management at the University of St. Gallen on the state and prospects of European communication professionals.

  17. The cyclic di-nucleotide c-di-AMP is an allosteric regulator of metabolic enzyme function

    Science.gov (United States)

    Precit, Mimi; Delince, Matthieu; Pensinger, Daniel; Huynh, TuAnh Ngoc; Jurado, Ashley R.; Goo, Young Ah; Sadilek, Martin; Iavarone, Anthony T.; Sauer, John-Demian; Tong, Liang; Woodward, Joshua J.

    2014-01-01

    SUMMARY Cyclic di-adenosine monophosphate (c-di-AMP) is a broadly conserved second messenger required for bacterial growth and infection. However, the molecular mechanisms of c-di-AMP signaling are still poorly understood. Using a chemical proteomics screen for c-di-AMP interacting proteins in the pathogen Listeria monocytogenes, we identified several broadly conserved protein receptors, including the central metabolic enzyme pyruvate carboxylase (LmPC). Biochemical and crystallographic studies of the LmPC-c-di-AMP interaction revealed a previously unrecognized allosteric regulatory site 25 Å from the active site. Mutations in this site disrupted c-di-AMP binding and affected enzyme catalysis of LmPC as well as PC from pathogenic Enterococcus faecalis. C-di-AMP depletion resulted in altered metabolic activity in L. monocytogenes. Correction of this metabolic imbalance rescued bacterial growth, reduced bacterial lysis, and resulted in enhanced bacterial burdens during infection. These findings greatly expand the c-di-AMP signaling repertoire and reveal a central metabolic regulatory role for a cyclic di-nucleotide. PMID:25215494

  18. Modulation of Pantothenate Kinase 3 Activity by Small Molecules that Interact with the Substrate/Allosteric Regulatory Domain

    Energy Technology Data Exchange (ETDEWEB)

    Leonardi, Roberta; Zhang, Yong-Mei; Yun, Mi-Kyung; Zhou, Ruobing; Zeng, Fu-Yue; Lin, Wenwei; Cui, Jimmy; Chen, Taosheng; Rock, Charles O.; White, Stephen W.; Jackowski, Suzanne (SJCH)

    2010-09-27

    Pantothenate kinase (PanK) catalyzes the rate-controlling step in coenzyme A (CoA) biosynthesis. PanK3 is stringently regulated by acetyl-CoA and uses an ordered kinetic mechanism with ATP as the leading substrate. Biochemical analysis of site-directed mutants indicates that pantothenate binds in a tunnel adjacent to the active site that is occupied by the pantothenate moiety of the acetyl-CoA regulator in the PanK3 acetyl-CoA binary complex. A high-throughput screen for PanK3 inhibitors and activators was applied to a bioactive compound library. Thiazolidinediones, sulfonylureas and steroids were inhibitors, and fatty acyl-amides and tamoxifen were activators. The PanK3 activators and inhibitors either stimulated or repressed CoA biosynthesis in HepG2/C3A cells. The flexible allosteric acetyl-CoA regulatory domain of PanK3 also binds the substrates, pantothenate and pantetheine, and small molecule inhibitors and activators to modulate PanK3 activity.

  19. Negative Allosteric Modulators Selective for The NR2B Subtype of The NMDA Receptor Impair Cognition in Multiple Domains.

    Science.gov (United States)

    Weed, Michael R; Bookbinder, Mark; Polino, Joseph; Keavy, Deborah; Cardinal, Rudolf N; Simmermacher-Mayer, Jean; Cometa, Fu-ni L; King, Dalton; Thangathirupathy, Srinivasan; Macor, John E; Bristow, Linda J

    2016-01-01

    Antidepressant activity of N-methyl-D-aspartate (NMDA) receptor antagonists and negative allosteric modulators (NAMs) has led to increased investigation of their behavioral pharmacology. NMDA antagonists, such as ketamine, impair cognition in multiple species and in multiple cognitive domains. However, studies with NR2B subtype-selective NAMs have reported mixed results in rodents including increased impulsivity, no effect on cognition, impairment or even improvement of some cognitive tasks. To date, the effects of NR2B-selective NAMs on cognitive tests have not been reported in nonhuman primates. The current study evaluated two selective NR2B NAMs, CP101,606 and BMT-108908, along with the nonselective NMDA antagonists, ketamine and AZD6765, in the nonhuman primate Cambridge Neuropsychological Test Automated Battery (CANTAB) list-based delayed match to sample (list-DMS) task. Ketamine and the two NMDA NR2B NAMs produced selective impairments in memory in the list-DMS task. AZD6765 impaired performance in a non-specific manner. In a separate cohort, CP101,606 impaired performance of the nonhuman primate CANTAB visuo-spatial Paired Associates Learning (vsPAL) task with a selective impairment at more difficult conditions. The results of these studies clearly show that systemic administration of a selective NR2B NAM can cause transient cognitive impairment in multiple cognitive domains. PMID:26105137

  20. The Central domain of RyR1 is the transducer for long-range allosteric gating of channel opening.

    Science.gov (United States)

    Bai, Xiao-Chen; Yan, Zhen; Wu, Jianping; Li, Zhangqiang; Yan, Nieng

    2016-09-01

    The ryanodine receptors (RyRs) are intracellular calcium channels responsible for rapid release of Ca(2+) from the sarcoplasmic/endoplasmic reticulum (SR/ER) to the cytoplasm, which is essential for the excitation-contraction (E-C) coupling of cardiac and skeletal muscles. The near-atomic resolution structure of closed RyR1 revealed the molecular details of this colossal channel, while the long-range allosteric gating mechanism awaits elucidation. Here, we report the cryo-EM structures of rabbit RyR1 in three closed conformations at about 4 Å resolution and an open state at 5.7 Å. Comparison of the closed RyR1 structures shows a breathing motion of the cytoplasmic platform, while the channel domain and its contiguous Central domain remain nearly unchanged. Comparison of the open and closed structures shows a dilation of the S6 tetrahelical bundle at the cytoplasmic gate that leads to channel opening. During the pore opening, the cytoplasmic "O-ring" motif of the channel domain and the U-motif of the Central domain exhibit coupled motion, while the Central domain undergoes domain-wise displacement. These structural analyses provide important insight into the E-C coupling in skeletal muscles and identify the Central domain as the transducer that couples the conformational changes of the cytoplasmic platform to the gating of the central pore. PMID:27468892

  1. An Integrated Approach for Screening and Identification of Positive Allosteric Modulators of N-Methyl-D-Aspartate Receptors.

    Science.gov (United States)

    Jambrina, Enrique; Cerne, Rok; Smith, Emery; Scampavia, Louis; Cuadrado, Maria; Findlay, Jeremy; Krambis, Michael J; Wakulchik, Mark; Chase, Peter; Brunavs, Michael; Burris, Kevin D; Gallagher, Peter; Spicer, Timothy P; Ursu, Daniel

    2016-06-01

    N-methyl-D-aspartate receptors (NMDARs) are ionotropic glutamate receptors that play an important role in synaptic plasticity and learning and memory formation. Malfunctioning of NMDARs, in particular the reduction in NMDAR activity, is thought to be implicated in major neurological disorders. NMDAR positive allosteric modulators (PAMs) represent potential therapeutic interventions for restoring normal NMDAR function. We report a novel screening approach for identification and characterization of NMDAR-PAMs. The approach combines high-throughput fluorescence imaging with automated electrophysiological recording of glutamate-evoked responses in HEK-293 cells expressing NR1/NR2A NMDAR subunits. Initial high-throughput screening (HTS) of a chemical library containing >810,000 compounds using a calcium flux assay in 1536-well plate format identified a total of 864 NMDAR-PAMs. Concentration response determination in both calcium flux and automated electrophysiological assays found several novel chemical series with EC50 values between 0.49 and 10 µM. A small subset (six series) was selected and analyzed for pharmacological properties, subtype selectivity, mode of action, and activity at native NMDARs. Our approach demonstrates the successful application of HTS functional assays that led to identification of NMDAR-PAMs providing the foundation for further medicinal chemistry work that may lead to novel therapies for treatment of cognitive impairment associated with Alzheimer's disease and schizophrenia. PMID:26838761

  2. Nonlinear excitations match correlated motions unveiled by NMR in proteins: a new perspective on allosteric cross-talk

    International Nuclear Information System (INIS)

    In this paper we propose a novel theoretical framework for interpreting long-range dynamical correlations unveiled in proteins through NMR measurements. The theoretical rationale relies on the hypothesis that correlated motions in proteins may be reconstructed as large-scale, collective modes sustained by long-lived nonlinear vibrations known as discrete breathers (DB) localized at key, hot-spot sites. DBs are spatially localized modes, whose nonlinear nature hinders resonant coupling with the normal modes, thus conferring them long lifetimes as compared to normal modes. DBs have been predicted to exist in proteins, localized at few hot-spot residues typically within the stiffest portions of the structure. We compute DB modes analytically in the framework of the nonlinear network model, showing that the displacement patterns of many DBs localized at key sites match to a remarkable extent the experimentally uncovered correlation blueprint. The computed dispersion relations prove that it is physically possible for some of these DBs to be excited out of thermal fluctuations at room temperature. Based on our calculations, we speculate that transient energy redistribution among the vibrational modes in a protein might favor the emergence of DB-like bursts of long-lived energy at hot-spot sites with lifetimes in the ns range, able to sustain critical, function-encoding correlated motions. More generally, our calculations provide a novel quantitative tool to predict fold-spanning dynamical pathways of correlated residues that may be central to allosteric cross-talk in proteins. (paper)

  3. Predicting Allosteric Effects from Orthosteric Binding in Hsp90-Ligand Interactions: Implications for Fragment-Based Drug Design

    Science.gov (United States)

    Larsson, Andreas; Nordlund, Paer; Jansson, Anna; Anand, Ganesh S.

    2016-01-01

    A key question in mapping dynamics of protein-ligand interactions is to distinguish changes at binding sites from those associated with long range conformational changes upon binding at distal sites. This assumes a greater challenge when considering the interactions of low affinity ligands (dissociation constants, KD, in the μM range or lower). Amide hydrogen deuterium Exchange mass spectrometry (HDXMS) is a robust method that can provide both structural insights and dynamics information on both high affinity and transient protein-ligand interactions. In this study, an application of HDXMS for probing the dynamics of low affinity ligands to proteins is described using the N-terminal ATPase domain of Hsp90. Comparison of Hsp90 dynamics between high affinity natural inhibitors (KD ~ nM) and fragment compounds reveal that HDXMS is highly sensitive in mapping the interactions of both high and low affinity ligands. HDXMS reports on changes that reflect both orthosteric effects and allosteric changes accompanying binding. Orthosteric sites can be identified by overlaying HDXMS onto structural information of protein-ligand complexes. Regions distal to orthosteric sites indicate long range conformational changes with implications for allostery. HDXMS, thus finds powerful utility as a high throughput method for compound library screening to identify binding sites and describe allostery with important implications for fragment-based ligand discovery (FBLD). PMID:27253209

  4. Structural Mechanisms of Peptide Recognition and Allosteric Modulation of Gene Regulation by the RRNPP Family of Quorum-Sensing Regulators.

    Science.gov (United States)

    Do, Hackwon; Kumaraswami, Muthiah

    2016-07-17

    The members of RRNPP family of bacterial regulators sense population density-specific secreted oligopeptides and modulate the expression of genes involved in cellular processes, such as sporulation, competence, virulence, biofilm formation, conjugative plasmid transfer and antibiotic resistance. Signaling by RRNPP regulators include several steps: generation and secretion of the signaling oligopeptides, re-internalization of the signaling molecules into the cytoplasm, signal sensing by the cytosolic RRNPP regulators, signal-specific allosteric structural changes in the regulators, and interaction of the regulators with their respective regulatory target and gene regulation. The recently determined structures of the RRNPP regulators provide insight into the mechanistic aspects for several steps in this signaling circuit. In this review, we discuss the structural principles underlying peptide specificity, regulatory target recognition, and ligand-induced allostery in RRNPP regulators and its impact on gene regulation. Despite the conserved tertiary structure of these regulators, structural analyses revealed unexpected diversity in the mechanism of activation and molecular strategies that couple the peptide-induced allostery to gene regulation. Although these structural studies provide a sophisticated understanding of gene regulation by RRNPP regulators, much needs to be learned regarding the target DNA binding by yet-to-be characterized RNPP regulators and the several aspects of signaling by Rgg regulators. PMID:27283781

  5. An Allosteric Cross-Talk Between the Activation Loop and the ATP Binding Site Regulates the Activation of Src Kinase

    Science.gov (United States)

    Pucheta-Martínez, Encarna; Saladino, Giorgio; Morando, Maria Agnese; Martinez-Torrecuadrada, Jorge; Lelli, Moreno; Sutto, Ludovico; D’Amelio, Nicola; Gervasio, Francesco Luigi

    2016-04-01

    Phosphorylation of the activation loop is a fundamental step in the activation of most protein kinases. In the case of the Src tyrosine kinase, a prototypical kinase due to its role in cancer and its historic importance, phosphorylation of tyrosine 416 in the activation loop is known to rigidify the structure and contribute to the switch from the inactive to a fully active form. However, whether or not phosphorylation is able per-se to induce a fully active conformation, that efficiently binds ATP and phosphorylates the substrate, is less clear. Here we employ a combination of solution NMR and enhanced-sampling molecular dynamics simulations to fully map the effects of phosphorylation and ATP/ADP cofactor loading on the conformational landscape of Src tyrosine kinase. We find that both phosphorylation and cofactor binding are needed to induce a fully active conformation. What is more, we find a complex interplay between the A-loop and the hinge motion where the phosphorylation of the activation-loop has a significant allosteric effect on the dynamics of the C-lobe.

  6. Predicting Allosteric Effects from Orthosteric Binding in Hsp90-Ligand Interactions: Implications for Fragment-Based Drug Design.

    Directory of Open Access Journals (Sweden)

    Arun Chandramohan

    2016-06-01

    Full Text Available A key question in mapping dynamics of protein-ligand interactions is to distinguish changes at binding sites from those associated with long range conformational changes upon binding at distal sites. This assumes a greater challenge when considering the interactions of low affinity ligands (dissociation constants, KD, in the μM range or lower. Amide hydrogen deuterium Exchange mass spectrometry (HDXMS is a robust method that can provide both structural insights and dynamics information on both high affinity and transient protein-ligand interactions. In this study, an application of HDXMS for probing the dynamics of low affinity ligands to proteins is described using the N-terminal ATPase domain of Hsp90. Comparison of Hsp90 dynamics between high affinity natural inhibitors (KD ~ nM and fragment compounds reveal that HDXMS is highly sensitive in mapping the interactions of both high and low affinity ligands. HDXMS reports on changes that reflect both orthosteric effects and allosteric changes accompanying binding. Orthosteric sites can be identified by overlaying HDXMS onto structural information of protein-ligand complexes. Regions distal to orthosteric sites indicate long range conformational changes with implications for allostery. HDXMS, thus finds powerful utility as a high throughput method for compound library screening to identify binding sites and describe allostery with important implications for fragment-based ligand discovery (FBLD.

  7. Effects of alpha-7 nicotinic acetylcholine receptor positive allosteric modulator on lipopolysaccharide-induced neuroinflammatory pain in mice.

    Science.gov (United States)

    Abbas, Muzaffar; Rahman, Shafiqur

    2016-07-15

    Evidence indicates that microglial activation contributes to the pathophysiology and maintenance of neuroinflammatory pain involving central nervous system alpha-7 nicotinic acetylcholine receptors. The objective of the present study was to determine the effects of 3a,4,5,9b-Tetrahydro-4-(1-naphthalenyl)-3H-cyclopentan[c]quinoline-8-sulfonamide (TQS), an alpha-7 nicotinic acetylcholine receptor positive allosteric modulator (PAM), on tactile allodynia and thermal hyperalgesia following lipopolysaccharide (LPS)-induced microglial activation in hippocampus, a neuroinflammatory pain model in mice. In addition, we examined the effects of TQS on microglial activation marker, an ionized calcium-binding adapter molecule 1 (Iba-1), in the hippocampus may be associated with neuroinflammatory pain. Pretreatment of TQS (4mg/kg) significantly reduced LPS (1mg/kg)-induced tactile allodynia and thermal hyperalgesia. Moreover, pretreatment of methyllycaconitine (3mg/kg) significantly reversed TQS-induced antiallodynic and antihyperalgesic responses indicating the involvement of alpha-7 nicotinic acetylcholine receptor. Pretreatment of TQS significantly decreased LPS-induced increased in hippocampal Iba-1 expression. Overall, these results suggest that TQS reduces LPS-induced neuroinflammatory pain like symptoms via modulating microglial activation likely in the hippocampus and/or other brain region by targeting alpha-7 nicotinic acetylcholine receptor. Therefore, alpha-7 nicotinic acetylcholine receptor PAM such as TQS could be a potential drug candidate for the treatment of neuroinflammatory pain. PMID:27154173

  8. Accessibility of different histone H3-binding domains of UHRF1 is allosterically regulated by phosphatidylinositol 5-phosphate.

    Science.gov (United States)

    Gelato, Kathy A; Tauber, Maria; Ong, Michelle S; Winter, Stefan; Hiragami-Hamada, Kyoko; Sindlinger, Julia; Lemak, Alexander; Bultsma, Yvette; Houliston, Scott; Schwarzer, Dirk; Divecha, Nullin; Arrowsmith, Cheryl H; Fischle, Wolfgang

    2014-06-19

    UHRF1 is a multidomain protein crucially linking histone H3 modification states and DNA methylation. While the interaction properties of its specific domains are well characterized, little is known about the regulation of these functionalities. We show that UHRF1 exists in distinct active states, binding either unmodified H3 or the H3 lysine 9 trimethylation (H3K9me3) modification. A polybasic region (PBR) in the C terminus blocks interaction of a tandem tudor domain (TTD) with H3K9me3 by occupying an essential peptide-binding groove. In this state the plant homeodomain (PHD) mediates interaction with the extreme N terminus of the unmodified H3 tail. Binding of the phosphatidylinositol phosphate PI5P to the PBR of UHRF1 results in a conformational rearrangement of the domains, allowing the TTD to bind H3K9me3. Our results define an allosteric mechanism controlling heterochromatin association of an essential regulatory protein of epigenetic states and identify a functional role for enigmatic nuclear phosphatidylinositol phosphates. PMID:24813945

  9. Communication Motives of Assertive and Responsive Communicators.

    Science.gov (United States)

    Anderson, Carolyn M.; Martin, Matthew M.

    1995-01-01

    Finds that competent communicators (high assertive, high responsive) communicated from needs for affection, pleasure, and inclusion more than noncompetent (low assertive, low responsive), submissive (low assertive, high responsive), and aggressive (high assertive, low responsive) individuals. Shows that aggressive types communicated more from…

  10. CULTURE OF COMMUNICATIVE BEHAVIOR IN INTERPERSONAL COMMUNICATION

    OpenAIRE

    MARTYNOVA Е.М.

    2014-01-01

    The article is devoted to the linguistic and communicative norms the successful dialogic interaction should correspond to. It touches upon the central element of communicative culture the culture of speech. Much attention is given to the barriers in speech interaction which can cause communicative failures

  11. Digital Marketing Communication

    OpenAIRE

    Margherita Corniani

    2006-01-01

    Digital marketing communication is directed to profiled targets, which are active in the communication process. Every communication flow can ask for an information answer from the market. This opportunity grants immediate feed-backs and feed-forwards, so that digital communication can be easily and cheaply measured; digital communication flows are diffused at costs that are getting lower and lower, but it asks specialized and deep competences to communication managers. The ease in the flowing...

  12. The Obstacles in Cross-cultural Communication

    Institute of Scientific and Technical Information of China (English)

    WANG Jian-hua

    2009-01-01

    In Cross-cultural communication,the ability of the languages and the ability of the cultures ale the crucial factors in the communicating activities.People with the sanle cultural background communicate with each other easily and smoothly,and understand each other better,and there are fewer or no obstacles in their communication at all.The different cultural backgrounds and traditions,the different social customs and everyday living habits,and the different values all will affect the communication quality and will surely result in obstacles in cross-cultural communication.The obstacles which frequently occur in the cross-cultural communication are:ethnocentrism,stereotyping,prejudice,and the different cultural backgrounds.In order to do away with the obstacles and to make the communication smoothly and successfully,the communicating parties both should observe the cooperative principles and politeness principles.And what's more,they must discard their own prejudices,and respect others,together to fulfill the cross-cultural communicating activities.

  13. Changing Organizational Communication Practices and Norms: A Framework

    OpenAIRE

    Suchan, Jim

    2006-01-01

    Journal of Business and Technical Communication, 20(1), pp. 1-43, 2006. Efforts to get workers to change significantly their communication practices often fail. This failure occurs because external consultants, who are often academics, and internal organizational development specialists see changing communication practices as merely introducing new skills rather than altering the way workers habitually think and talk about communication. In this article, the author uses organizational th...

  14. Intervehicle Communication Research – Communication Scenarios

    Directory of Open Access Journals (Sweden)

    Šarūnas Stanaitis

    2011-03-01

    Full Text Available Recently intervehicle communications are attracting much attention from industry and academia. Upcoming standard for intervehicle communication IEEE 802.11p, known as Wireless Access in Vehicular Environments (WAVE, is still in its draft stage, but already coming into final standardization phase. Problematic, regarding mobile WAVE nodes, are described in several articles, simulations prepared and experiments done. But most of these works do not consider possible maximal communication load. This paper presents intervehicle communication scenario in respect to radio communications, mobility and other aspects of vehicular environments.Article in English

  15. Predicting Emotions in Facial Expressions from the Annotations in Naturally Occurring First Encounters

    DEFF Research Database (Denmark)

    Navarretta, Costanza

    2014-01-01

    tokens. We also investigate the relation between emotions and the communicative functions of facial expressions. Both emotion labels and their values in a three dimensional space are identified. The three dimensions are Pleasure, Arousal and Dominance. The results of our experiments indicate that the......This paper deals with the automatic identification of emotions from the manual annotations of the shape and functions of facial expressions in a Danish corpus of video recorded naturally occurring first encounters. More specifically, a support vector classified is trained on the corpus annotations...... to identify emotions in facial expressions. In the classification experiments, we test to what extent emotions expressed in naturally-occurring conversations can be identified automatically by a classifier trained on the manual annotations of the shape of facial expressions and co-occurring speech...

  16. Intercultural Communication and ELT

    Institute of Scientific and Technical Information of China (English)

    许玲

    2013-01-01

    Intercultural communication seeks to understand how people from different countries or cultures act, communicate and perceive the world around them. To develop students’culture awareness and intercultural communication skills have been incorporated in ELT curriculum. This paper will focus on culture awareness, cultural disparities and cross-cultural communica-tion in ELT context.

  17. Internet-Based Communication

    Science.gov (United States)

    Gernsbacher, Morton Ann

    2014-01-01

    Google the question, "How is the Internet changing the way we communicate?," and you will find no shortage of opinions, or fears, about the Internet altering the way we communicate. Although the Internet is not necessarily making communication briefer (neither is the Internet making communication less formal), the Internet is manifesting…

  18. Shuttle Communications Blackout Study

    Science.gov (United States)

    Haben, R. L.; Budica, R. J.

    1983-01-01

    Space Shuttle Orbiter Entry Communications Blackout Study computer program models, investigates, and predicts communication blackout envelopes based on mission entry trajectory and associated data from tracking stations. Of interest to those designing and using communications systems susceptible to blackout. Program is readily adapted to predict entry communications blackout for any nonablative entry vehicle.

  19. Adolescent Interpersonal Communication Patterns

    OpenAIRE

    Grobler, S

    1999-01-01

    Adolescents are admitted to psychiatric wards presenting with psychiatric problems which are essentially secondary to problematic interpersonal relationships. Successful interpersonal relationships however depend on effective interpersonal communication. Therefore the aim of research on adolescent interpersonal communication was to explore and describe the interpersonal communication patterns of adolescents and to develop an interpersonal communication skills approach to facilitate adolescent...

  20. Communications technology satellite

    Science.gov (United States)

    1976-01-01

    A description of the Communications Technology Satellite (CTS), its planned orbit, its experiments, and associated ground facilities was given. The communication experiments, to be carried out by a variety of groups in both the United States and Canada, include tele-education, tele-medicine, community interaction, data communications and broadcasting. A historical summary of communications satellite development was also included.

  1. On Communication Models

    Institute of Scientific and Technical Information of China (English)

    蒋娜; 谢有琪

    2012-01-01

    With the development of human society, the social hub enlarges beyond one community to the extent that the world is deemed as a community as a whole. Communication, therefore, plays an increasingly important role in our daily life. As a consequence, communication model or the definition of which is not so much a definition as a guide in communication. However, some existed communication models are not as practical as it was. This paper tries to make an overall contrast among three communication models Coded Model, Gable Communication Model and Ostensive Inferential Model, to see how they assist people to comprehend verbal and non -verbal communication.

  2. Communications device identification methods, communications methods, wireless communications readers, wireless communications systems, and articles of manufacture

    Science.gov (United States)

    Steele, Kerry D [Kennewick, WA; Anderson, Gordon A [Benton City, WA; Gilbert, Ronald W [Morgan Hill, CA

    2011-02-01

    Communications device identification methods, communications methods, wireless communications readers, wireless communications systems, and articles of manufacture are described. In one aspect, a communications device identification method includes providing identification information regarding a group of wireless identification devices within a wireless communications range of a reader, using the provided identification information, selecting one of a plurality of different search procedures for identifying unidentified ones of the wireless identification devices within the wireless communications range, and identifying at least some of the unidentified ones of the wireless identification devices using the selected one of the search procedures.

  3. Engineering PQQ-glucose dehydrogenase into an allosteric electrochemical Ca(2+) sensor.

    Science.gov (United States)

    Guo, Zhong; Johnston, Wayne A; Stein, Viktor; Kalimuthu, Palraj; Perez-Alcala, Siro; Bernhardt, Paul V; Alexandrov, Kirill

    2016-01-11

    Electrochemical biosensors convert biological events to an electrical current. To date most electrochemical biosensors exploit activities of naturally occurring enzymes. Here we demonstrated that insertion of a calmodulin domain into the redox enzyme PQQ-glucose dehydrogenase resulted in a selective Ca(2+) biosensor that could be used to rapidly measure Ca(2+) concentrations in human biological fluids. We were able to convert a point-of-care glucometer into Ca(2+) monitor by refurbishing it with the developed biosensor. We propose that similar engineering strategies may be used to create highly specific electrochemical biosensors to other analytes. Compatibility with cheap and ubiquitous amperometric detectors is expected to accelerate progression of these biosensors into clinical applications. PMID:26528736

  4. Organizational Communication: Communication and Motivation in the Workplace

    Directory of Open Access Journals (Sweden)

    Sari Ramadanty

    2016-01-01

    nonverbal communication, interpersonal communication leadership and communication climate have a significant role to form employee motivation. Nonverbal communication has slightly strong role in shaping the positive motivation to employee. The role includes body communication, facial communication and eye communication. Interpersonal communication leader is based on the satisfaction level of information between management and employees. Management and transparency in openness in downward communication under the form of information from superiors are by listening the communication between supervisors and employees are running smoothly.

  5. Netiquette in Electronic Communication

    OpenAIRE

    Tomáš Kozík; Jozefína Slivová

    2014-01-01

    Electronic mail and electronic communications systems are considered significant and effective tools of communication. One of the most widespread electronic communication tools is e - mail communication. In order to avoid misinterpretation of the report on the side of the recipient, it is need to pay attention to the writing of e - mail messages as well as to their content. With the continuous expansion of the use of electronic communication there have gradually developed certain rules of...

  6. Newnes communications technology handbook

    CERN Document Server

    Lewis, Geoff

    1994-01-01

    Newnes Communications Technology Handbook provides a discussion on different topics relevant to communications technology. The book is comprised of 39 chapters that tackle a wide variety of concern in communications technology. The coverage of the text includes technologies, such as analog digital communications systems, radio frequency receiver, and satellite systems. The book also discusses some methods and techniques used in communications technology, including mixer signal processing, modulation and demodulation, and spread spectrum techniques. The text will be of great use to engineers, t

  7. Conceptual Model for Communication

    OpenAIRE

    Zahra'a Fadel; Ala'a Alsaqa; Sabah Al-Fedaghi

    2009-01-01

    A variety of idealized models of communication systems exist, and all may have something in common. Starting with Shannon’s communication model and ending with the OSI model, this paper presents progressively more advanced forms of modeling of communication systems by tying communication models together based on the notion of flow. The basic communication process is divided into different spheres (sources, channels, and destinations), each with its own five interior stages: receiving, process...

  8. Evaluation of Marketing Communication

    OpenAIRE

    Langmaier, Jan

    2013-01-01

    This Bachelor thesis is focused on marketing communication of the Pension Corto. Work is divided into two main parts. In first, theoretical part are defined terms such as marketing, marketing mix and of course marketing communication together with communication mix with the respect on aspects of tourism. In practical part is introduced the Pension Corto, and analysis of individual parts of its communication mix. Based on personal experience, the marketing communication analysis and on results...

  9. Effective communication with seniors

    OpenAIRE

    PONCAROVÁ, Ester

    2008-01-01

    My bachelor thesis is called "The Effective Communication With Seniors". The aim of this thesis is to describe communication, its various kinds and the basic principles of the effective communication. I will also describe the communication with seniors suffering from dementia. Another aim of this thesis is to find out whether workers in the senior houses know and use the principles of the effective communication.

  10. Bidirectional coherent classical communication

    OpenAIRE

    Harrow, Aram W.; Leung, Debbie W.

    2005-01-01

    A unitary interaction coupling two parties enables quantum or classical communication in both the forward and backward directions. Each communication capacity can be thought of as a tradeoff between the achievable rates of specific types of forward and backward communication. Our first result shows that for any bipartite unitary gate, bidirectional coherent classical communication is no more difficult than bidirectional classical communication — they have the same achievable rate regions. ...

  11. Silence in Intercultural communication

    Institute of Scientific and Technical Information of China (English)

    Guo Jun

    2012-01-01

    In communication, most of people's attention focuses on verbal communication, nonverbal language as a means of exchange is often ignored. However, nonverbal language continues sending signals, and most of these signals are sent to conversational partners unconsciously. So correct understanding of these signals will help people improve effectiveness of communication. This article will focus on silence, a major part of nonverbal communication, exploring its communicative functions and cultural differences.

  12. Improving Employee Communications

    Energy Technology Data Exchange (ETDEWEB)

    A. R. Pomplun; B. J. Kelley; B. L. Schrader; R. C. Christma; R. H. Tucker

    1999-01-01

    This report summarizes the findings and recommendation of the Sandia/California Site Communications Team based on activities during FY98. The important conclusions are that effective communications are everyone's business; careful planning and execution are required for effective communications; and communication planning can be described in steps easily understood by everyone. Included in this report is a quick reference (toolkit) for communication planning and implementation.

  13. European Communication Report 2007

    OpenAIRE

    Fieseler, Christian; Meckel, Miriam; Hoffmann, Christian Pieter

    2007-01-01

    What will be the major challenges for Communication professionals in the future? How influential are communicators within their organisations? How much money do they earn? How satisfied are they with their jobs? These and other important questions are being answered by the "European Communication Report 2007". The survey among almost 1,200 communication professionals across Europe portrays the professional backgrounds, challenges and working environments of communication directors and spok...

  14. Trends in communications satellites

    CERN Document Server

    Curtin, Denis J

    1979-01-01

    Trends in Communications Satellites offers a comprehensive look at trends and advances in satellite communications, including experimental ones such as NASA satellites and those jointly developed by France and Germany. The economic aspects of communications satellites are also examined. This book consists of 16 chapters and begins with a discussion on the fundamentals of electrical communications and their application to space communications, including spacecraft, earth stations, and orbit and wavelength utilization. The next section demonstrates how successful commercial satellite communicati

  15. Development of a high throughput screen for allosteric modulators of melanocortin-4 receptor signaling using a real time cAMP assay.

    Science.gov (United States)

    Pantel, Jacques; Williams, Savannah Y; Mi, Dehui; Sebag, Julien; Corbin, Jackie D; Weaver, C David; Cone, Roger D

    2011-06-11

    The melanocortin MC(4) receptor is a potential target for the development of drugs for both obesity and cachexia. Melanocortin MC(4) receptor ligands known thus far are orthosteric agonists or antagonists, however the agonists, in particular, have generally exhibited unwanted side effects. For some receptors, allosteric modulators are expected to reduce side-effect profiles. To identify allosteric modulators of the melanocortin MC(4) receptor, we created HEK293 cell lines coexpressing the human melanocortin MC(4) receptor and a modified luciferase-based cAMP sensor. Monitoring luminescence as a readout of real-time intracellular cAMP concentration, we demonstrate that this cell line is able to report melanocortin agonist responses, as well as inverse agonist response to the physiological AgRP peptide. Based on the MC4R-GLO cell line, we developed an assay that was shown to meet HTS standards (Z'=0.50). A pilot screen run on the Microsource Spectrum compound library (n=2000) successfully identified 62 positive modulators. This screen identified predicted families of compounds: β(2)AR agonists - the β(2)AR being endogenously expressed in HEK293 cells, an adenylyl cyclase activator and finally a distribution of phosphodiesterase (PDE) inhibitors well characterized or recently identified. In this last category, we identified a structural family of coumarin-derived compounds (imperatorin, osthol and prenyletin), along with deracoxib, a drug in veterinary use for its COX2 inhibitory properties. This latter finding unveiled a new off-target mechanism of action for deracoxib as a PDE inhibitor. Overall, these data are the first report of a HTS for allosteric modulators for a Gs protein coupled receptor. PMID:21296065

  16. DF2755A, a novel non-competitive allosteric inhibitor of CXCR1/2, reduces inflammatory and post-operative pain.

    Science.gov (United States)

    Lopes, Alexandre H; Brandolini, Laura; Aramini, Andrea; Bianchini, Gianluca; Silva, Rangel L; Zaperlon, Ana C; Verri, Waldiceu A; Alves-Filho, José C; Cunha, Fernando Q; Teixeira, Mauro M; Allegretti, Marcello; Cunha, Thiago M

    2016-01-01

    The activation of CXCR1/2 has been implicated in the genesis of inflammatory and postoperative pain. Here, we investigated a novel orally acting allosteric inhibitor of CXCR1/2 (DF2755A) and evaluated its antinociceptive effect in several models of inflammatory and post-operatory pain. DF2755A was tested in vitro for efficacy in the chemotaxis assay, selectivity and toxicity. In vivo, C57Bl/6 mice were treated orally with DF2755A and the following experiments were performed: pharmacokinetic profile; inflammatory hyperalgesia models using electronic pressure meter test; neutrophil migration assay assessed by myeloperoxidase assay. DF2755A selectively inhibited neutrophil chemotaxis induced by CXCR1/2 ligands without effect on CXCL8 binding to neutrophils. A single mutation of the allosteric site at CXCR1 abrogated the inhibitory effect of DF2755A on CXCL8-induced chemotaxis. DF2755A given orally was well absorbed (88.2%), and it was able to reduce, in a dose (3-30mg/kg)-dependent manner, inflammatory hyperalgesia induced by carrageenan, LPS and CXCL1/KC as well as neutrophil recruitment and IL-1β production. In addition, DF2755A was able to reduce post-incisional nociception. Therapeutic treatment with DF2755A reduced CFA-induced inflammatory hyperalgesia even when injected intrathecally. The present results indicate that DF2755A is a novel selective allosteric inhibitor of CXCR1/2 with a favorable oral pharmacokinetic profile. Furthermore, the results might suggest that DF2755A might be a candidate of a novel therapeutic option to control inflammatory and post-operative pain. PMID:26592483

  17. Intramolecular signal transmission in enterobacterial aspartate transcarbamylases II. Engineering co-operativity and allosteric regulation in the aspartate transcarbamylase of Erwinia herbicola.

    Science.gov (United States)

    Cunin, R; Rani, C S; Van Vliet, F; Wild, J R; Wales, M

    1999-12-17

    The aspartate transcarbamylase (ATCase) from Erwinia herbicola differs from the other investigated enterobacterial ATCases by its absence of homotropic co-operativity toward the substrate aspartate and its lack of response to ATP which is an allosteric effector (activator) of this family of enzymes. Nevertheless, the E. herbicola ATCase has the same quaternary structure, two trimers of catalytic chains with three dimers of regulatory chains ((c3)2(r2)3), as other enterobacterial ATCases and shows extensive primary structure conservation. In (c3)2(r2)3 ATCases, the association of the catalytic subunits c3 with the regulatory subunits r2 is responsible for the establishment of positive co-operativity between catalytic sites for the binding of aspartate and it dictates the pattern of allosteric response toward nucleotide effectors. Alignment of the primary sequence of the regulatory polypeptides from the E. herbicola and from the paradigmatic Escherichia coli ATCases reveals major blocks of divergence, corresponding to discrete structural elements in the E. coli enzyme. Chimeric ATCases were constructed by exchanging these blocks of divergent sequence between these two ATCases. It was found that the amino acid composition of the outermost beta-strand of a five-stranded beta-sheet in the effector-binding domain of the regulatory polypeptide is responsible for the lack of co-operativity and response to ATP of the E. herbicola ATCase. A novel structural element involved in allosteric signal recognition and transmission in this family of ATCases was thus identified. PMID:10600394

  18. Yellow fluorescent protein-based assay to measure GABA(A channel activation and allosteric modulation in CHO-K1 cells.

    Directory of Open Access Journals (Sweden)

    Teres Johansson

    Full Text Available The γ-aminobutyric acid A (GABA(A ion channels are important drug targets for treatment of neurological and psychiatric disorders. Finding GABA(A channel subtype selective allosteric modulators could lead to new improved treatments. However, the progress in this area has been obstructed by the challenging task of developing functional assays to support screening efforts and the generation of cells expressing functional GABA(A ion channels with the desired subtype composition. To address these challenges, we developed a yellow fluorescent protein (YFP-based assay to be able to study allosteric modulation of the GABA(A ion channel using cryopreserved, transiently transfected, assay-ready cells. We show for the first time how the MaxCyte STX electroporation instrument can be used to generate CHO-K1 cells expressing functional GABA(A α2β3γ2 along with a halide sensing YFP-H148Q/I152L (YFP-GABA(A2 cells. As a basis for a cell-based assay capable of detecting allosteric modulators, experiments with antagonist, ion channel blocker and modulators were used to verify GABA(A subunit composition and functionality. We found that the I(- concentration used in the YFP assay affected both basal quench of YFP and potency of GABA. For the first time the assay was used to study modulation of GABA with 7 known modulators where statistical analysis showed that the assay can distinguish modulatory pEC50 differences of 0.15. In conclusion, the YFP assay proved to be a robust, reproducible and inexpensive assay. These data provide evidence that the assay is suitable for high throughput screening (HTS and could be used to discover novel modulators acting on GABA(A ion channels.

  19. Selective Allosteric Inhibition of MMP9 Is Efficacious in Preclinical Models of Ulcerative Colitis and Colorectal Cancer.

    Directory of Open Access Journals (Sweden)

    Derek C Marshall

    Full Text Available Expression of matrix metalloproteinase 9 (MMP9 is elevated in a variety of inflammatory and oncology indications, including ulcerative colitis and colorectal cancer. MMP9 is a downstream effector and an upstream mediator of pathways involved in growth and inflammation, and has long been viewed as a promising therapeutic target. However, previous efforts to target matrix metalloproteinases (MMPs, including MMP9, have utilized broad-spectrum or semi-selective inhibitors. While some of these drugs showed signs of efficacy in patients, all MMP-targeted inhibitors have been hampered by dose-limiting toxicity or insufficient clinical benefit, likely due to their lack of specificity. Here, we show that selective inhibition of MMP9 did not induce musculoskeletal syndrome (a characteristic toxicity of pan-MMP inhibitors in a rat model, but did reduce disease severity in a dextran sodium sulfate-induced mouse model of ulcerative colitis. We also found that MMP9 inhibition decreased tumor growth and metastases incidence in a surgical orthotopic xenograft model of colorectal carcinoma, and that inhibition of either tumor- or stroma-derived MMP9 was sufficient to reduce primary tumor growth. Collectively, these data suggest that selective MMP9 inhibition is a promising therapeutic strategy for treatment of inflammatory and oncology indications in which MMP9 is upregulated and is associated with disease pathology, such as ulcerative colitis and colorectal cancer. In addition, we report the development of a potent and highly selective allosteric MMP9 inhibitor, the humanized monoclonal antibody GS-5745, which can be used to evaluate the therapeutic potential of MMP9 inhibition in patients.

  20. Structural basis for allosteric cross-talk between the asymmetric nucleotide binding sites of a heterodimeric ABC exporter.

    Science.gov (United States)

    Hohl, Michael; Hürlimann, Lea M; Böhm, Simon; Schöppe, Jendrik; Grütter, Markus G; Bordignon, Enrica; Seeger, Markus A

    2014-07-29

    ATP binding cassette (ABC) transporters mediate vital transport processes in every living cell. ATP hydrolysis, which fuels transport, displays positive cooperativity in numerous ABC transporters. In particular, heterodimeric ABC exporters exhibit pronounced allosteric coupling between a catalytically impaired degenerate site, where nucleotides bind tightly, and a consensus site, at which ATP is hydrolyzed in every transport cycle. Whereas the functional phenomenon of cooperativity is well described, its structural basis remains poorly understood. Here, we present the apo structure of the heterodimeric ABC exporter TM287/288 and compare it to the previously solved structure with adenosine 5'-(β,γ-imido)triphosphate (AMP-PNP) bound at the degenerate site. In contrast to other ABC exporter structures, the nucleotide binding domains (NBDs) of TM287/288 remain in molecular contact even in the absence of nucleotides, and the arrangement of the transmembrane domains (TMDs) is not influenced by AMP-PNP binding, a notion confirmed by double electron-electron resonance (DEER) measurements. Nucleotide binding at the degenerate site results in structural rearrangements, which are transmitted to the consensus site via two D-loops located at the NBD interface. These loops owe their name from a highly conserved aspartate and are directly connected to the catalytically important Walker B motif. The D-loop at the degenerate site ties the NBDs together even in the absence of nucleotides and substitution of its aspartate by alanine is well-tolerated. By contrast, the D-loop of the consensus site is flexible and the aspartate to alanine mutation and conformational restriction by cross-linking strongly reduces ATP hydrolysis and substrate transport. PMID:25030449

  1. Hydrogen-exchange labeling study of the allosteric R-state to T-state equilibrium in methemoglobin

    Science.gov (United States)

    McKinnie, R. E.; Englander, J. J.; Englander, S. W.

    1991-12-01

    Hydrogen-exchange labeling methods can be used to identify functionally important changes at positions all through a protein structure, can monitor the effect at these positions of structure changes anywhere in the protein, and can quantify these effects in terms of change in structural-stabilization free energy. These methods were used to study effects at two widely separated positions in human methemoglobin (metHb). The results show that the observed changes in hydrogen-exchange behavior reflect changes in the global R-state to T-state equilibrium, and specifically that stabilizing salt links at the α-chain N-terminus and the β-chain C-terminus are reformed in the R-T transition. The strong allosteric effector, inositol hexaphosphate (IHP), switches R-state methemoglobin to the T-state, but achieves a T/R equilibrium constant of only ≈ 3 (at pH=6.5, 0°C). Addition of the weaker effector, bezafibrate (Bzf), promotes this transition by an additional 0.7 kcal (T/R shifts to ≈ 12). Bzf alone is insufficient to cause the transition, indicating that R/T is 10 or more in stripped metHb under these conditions. However, R/T is small enough, not more than 103, to be reversed by the differential (T versus R) binding energy of IHP. The R-T transition caused by IHP and Bzf acting together can be reversed by some covalent modifications that sever the stabilizing salt links at the chain termini and thus favor transition back to the R-state.

  2. Calling patterns in human communication dynamics

    OpenAIRE

    Jiang, Zhi-Qiang; Xie, Wen-Jie; Li, Ming-Xia; Podobnik, Boris; Zhou, Wei-Xing; Stanley, H. Eugene

    2013-01-01

    Modern technologies not only provide a variety of communication modes, e.g., texting, cellphone conversation, and online instant messaging, but they also provide detailed electronic traces of these communications between individuals. These electronic traces indicate that the interactions occur in temporal bursts. Here, we study the inter-call durations of the 100,000 most-active cellphone users of a Chinese mobile phone operator. We confirm that the inter-call durations follow a power-law dis...

  3. A MULTIDISCIPLINARY APPROACH TO INTERCULTURAL COMMUNICATION

    OpenAIRE

    Stăncuţa Ramona DIMA-LAZA

    2012-01-01

    The present paper sets forth some ways of handling cultural complexity by approaching a multidisciplinary vision in order to explore cross-cultural communication and its framework. The main focus is on the conceptualization of intercultural competence and the way it occurs in applied linguistics, psychology or management studies. Intercultural communication has often been defined as an interaction between members belonging to various social groups, setting forth the similarities and differenc...

  4. Communication Styles and Business English Teaching

    Institute of Scientific and Technical Information of China (English)

    赵敏

    2008-01-01

    Nowadays,more and more people in the business community realize an urgent need to use English to cope with increasing economic globalization.Some people claim that they cannot communicate well because they do not learn English vocabulary and grammar well.However,we should understand that linguistic capability and communicative competency age two different things. Communicative competency is in fact largely affected by the culture that a language represents.This paper will focus on differences between the ways in which Chinese English speakers and native English speakers communicate in business simations, and furthermore,analyze their cultural roots.The purpose of this paper is to make people be more aware of the difllculdes or problems that may occur when using English in business activities,and therefore,improve the ability to reduce or avoid misunderstandings,embarrassment and even conflicts in cross-cultural communication.

  5. Selective Allosteric Antagonists for the G Protein-Coupled Receptor GPRC6A Based on the 2-Phenylindole Privileged Structure Scaffold

    DEFF Research Database (Denmark)

    Johansson, Henrik; Boesgaard, Michael Worch; Nørskov-Lauritsen, Lenea; Larsen, Inna; Kuhne, Sebastiaan; Gloriam, David E; Bräuner-Osborne, Hans; Sejer Pedersen, Daniel

    2015-01-01

    G protein-coupled receptors (GPCRs) represent a biological target class of fundamental importance in drug therapy. The GPRC6A receptor is a newly deorphanized class C GPCR that we recently reported for the first allosteric antagonists based on the 2-arylindole privileged structure scaffold (e.g., 1......, and 34b as antagonists at the GPRC6A receptor in the low micromolar range and show that 7 and 34b display >9-fold selectivity for the GPRC6A receptor over related GPCRs, making 7 and 34b the most potent and selective antagonists for the GPRC6A receptor reported to date....

  6. Allosteric-Site and Catalytic-Site Ligand Effects on PDE5 Functions are Associated with Distinct Changes in Physical Form of the Enzyme

    OpenAIRE

    Corbin, Jackie D.; Zoraghi, Roya; Francis, Sharron H.

    2009-01-01

    Native phosphodiesterase-5 (PDE5) homodimer contains distinct non-catalytic cGMP allosteric sites and catalytic sites for cGMP hydrolysis. Purified recombinant PDE5 was activated by pre-incubation with cGMP. Relatively low concentrations of cGMP produced a Native PAGE gel-shift of PDE5 from a single band position (lower band) to a band with decreased mobility (upper band); higher concentrations of cGMP produced a band of intermediate mobility (middle band) in addition to the upper band. Two p...

  7. Crystal structure of the HIV-1 integrase core domain in complex with sucrose reveals details of an allosteric inhibitory binding site

    Energy Technology Data Exchange (ETDEWEB)

    Wielens, Jerome; Headey, Stephen J.; Jeevarajah, Dharshini; Rhodes, David I.; Deadman, John; Chalmers, David K.; Scanlon, Martin J.; Parker, Michael W. (SVIMR-A); (Avea); (Monash IPS)

    2010-04-19

    HIV integrase (IN) is an essential enzyme in HIV replication and an important target for drug design. IN has been shown to interact with a number of cellular and viral proteins during the integration process. Disruption of these important interactions could provide a mechanism for allosteric inhibition of IN. We present the highest resolution crystal structure of the IN core domain to date. We also present a crystal structure of the IN core domain in complex with sucrose which is bound at the dimer interface in a region that has previously been reported to bind integrase inhibitors.

  8. Crystal structures of four indole derivatives as possible cannabinoid allosteric antagonists

    Directory of Open Access Journals (Sweden)

    Jamie R. Kerr

    2015-06-01

    Full Text Available The crystal structures of four indole derivatives with various substituents at the 2-, 3- and 5-positions of the ring system are described, namely, ethyl 3-(5-chloro-2-phenyl-1H-indol-3-yl-3-phenylpropanoate, C25H22ClNO2, (I, 2-bromo-3-(2-nitro-1-phenylethyl-1H-indole, C16H13BrN2O2, (II, 5-methoxy-3-(2-nitro-1-phenylethyl-2-phenyl-1H-indole, C23H20N2O3, (III, and 5-chloro-3-(2-nitro-1-phenylethyl-2-phenyl-1H-indole, C22H17ClN2O2, (IV. The dominant intermolecular interaction in each case is an N—H...O hydrogen bond, which generates either chains or inversion dimers. Weak C—H...O, C—H...π and π–π interactions occur in these structures but there is no consistent pattern amongst them. Two of these compounds act as modest enhancers of CB1 cannabanoid signalling and two are inactive.

  9. [The placebo effects of good communication].

    Science.gov (United States)

    van Vliet, L M; van Dulmen, S; Mistiaen, P; Bensing, J M

    2016-01-01

    - Good communication is important for patients and can elicit placebo effects: true psychobiological effects not attributable to the medical-technical intervention.- It is, however, often unclear which communication behaviours influence specific patient outcomes.- In this article we present insights into the potential effect of specific communication, via specific mechanisms, on specific patient outcomes, including patients' perception of pain.- A recent systematic review and additional literature demonstrate that (a) manipulating patients' expectations, (b) demonstrating empathy, and (c) providing procedural information, might influence patient outcomes.- These placebo effects probably occur via (a) neurobiological responses comparable to the effects of pain medication, (b) reduction of anxiety and stress, and PMID:27484421

  10. [Leadership and communication].

    Science.gov (United States)

    Henninger, Michael; Barth, Christina

    2009-01-01

    Medical leadership requires specific communication skills in order to meet professional demands. Communicative behaviour is usually highly automated and not necessarily conscious. Managerial communication competes against elaborated but not role-specific behaviour patterns, especially in critical situations. Accordingly, competent medical leadership requires the awareness of individual communication habits as well as the knowledge and ability to use conversation techniques suitable for a specific situational context. The training of leadership-related communication techniques requires the de-automation of existing skills and a problem-oriented construction and re-automation of new communication techniques. PMID:19545083

  11. Communication of influenza, influence of communication

    Directory of Open Access Journals (Sweden)

    Yurij Castelfranchi

    2009-06-01

    Full Text Available The recent events related to the spread of the influenza virus A (H1N1 have drawn again the attention of science communication experts to old issues, including a couple of issues we deem particularly important: risk communication and the role of scientific journalists in the society of knowledge.

  12. Advanced Communications Technology: Mobile Communications Requirements Report

    Science.gov (United States)

    1998-05-01

    The Coast Guard's mobile communications requirements will outstrip existing system capabilities, available capacity, and affordability by the late 1990s. This will require changes in the mix of mobile communications equipment and services used by operational units. New commercial mobile satellite services are available now, with many others arriving on the market between 1998 and 2003. These new services present unique opportunities to satisfy mission requirements, reduce investment in communications infrastructure, and realize more costeffective communications services. The Coast Guard Research and Development Center (R&DC) has undertaken an effort to identify and evaluate current and emerging satellite services that may be used to satisfy Coast Guard mobile communications requirements. As part of this effort, Anteon Corporation has been tasked by R&DC to collect the mobile communications functional requirements that have been identified by program managers. Anteon analysts have reviewed the Government Furnished Information (GFI) and researched other related documentation to identify and collect the requirements that may be used to describe the needed operating environment. Anteon analysts assessed the functional requirements to develop system requirements that describe the features that a communications system must provide to support the functional requirements. This report presents the current and projected Coast Guard mobile communications system requirements.

  13. Geo-communications : communicating earth science

    OpenAIRE

    Mitchell, Clive

    2013-01-01

    This presentation is that given as part of the MGeol course 'Communicating Earth Science' at Plymouth University by invitation of the course director (Professor Iain Stewart). It is a summary of the functions of the British Geological Survey (BGS) press office and the rationale used to communicate BGS science and technology.

  14. Communicators' perspective on snow avalanche risk communication

    Science.gov (United States)

    Charriere, M. K. M.; Bogaard, T.; Mostert, E.

    2014-12-01

    Among all the natural hazards, snow avalanches are the only ones for which a public danger scale is globally used. It consists of 5 levels of danger displayed with a given number and colour and for each of them, behavioural advices are provided. Even though this is standardized in most of the countries affected by this natural hazard, the tools (usually websites or smartphone applications) with which the information is disseminated to the general pubic differs, particularly in terms of target audience and level of details. This study aims at gathering the perspectives of several communicators that are responsible for these communication practices. The survey was created to assess how and why choices were made in the design process of the communication tools and to determine how their effectiveness is evaluated. Along with a review of existing avalanche risk communication tools, this study provides guidelines for communication and the evaluation of its effectiveness.

  15. 32 CFR 716.6 - Death occurring after active service.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 5 2010-07-01 2010-07-01 false Death occurring after active service. 716.6 Section 716.6 National Defense Department of Defense (Continued) DEPARTMENT OF THE NAVY PERSONNEL DEATH GRATUITY Provisions Applicable to the Navy and the Marine Corps § 716.6 Death occurring after...

  16. The insect repellent N,N-diethyl-m-toluamide (DEET) induces angiogenesis via allosteric modulation of the M3 muscarinic receptor in endothelial cells.

    Science.gov (United States)

    Legeay, Samuel; Clere, Nicolas; Hilairet, Grégory; Do, Quoc-Tuan; Bernard, Philippe; Quignard, Jean-François; Apaire-Marchais, Véronique; Lapied, Bruno; Faure, Sébastien

    2016-01-01

    The insect repellent N,N-diethyl-m-toluamide (DEET) has been reported to inhibit AChE (acetylcholinesterase) and to possess potential carcinogenic properties with excessive vascularization. In the present paper, we demonstrate that DEET specifically stimulates endothelial cells that promote angiogenesis which increases tumor growth. DEET activates cellular processes that lead to angiogenesis including proliferation, migration and adhesion. This is associated with an enhancement of NO production and VEGF expression in endothelial cells. M3 silencing or the use of a pharmacological M3 inhibitor abrogates all of these effects which reveals that DEET-induced angiogenesis is M3 sensitive. The experiments involving calcium signals in both endothelial and HEK cells overexpressing M3 receptors, as well as binding and docking studies demonstrate that DEET acts as an allosteric modulator of the M3 receptor. In addition, DEET inhibited AChE which increased acetylcholine bioavailability and binding to M3 receptors and also strengthened proangiogenic effects by an allosteric modulation. PMID:27345502

  17. Positive Allosteric Modulators of Type 5 Metabotropic Glutamate Receptors (mGluR5 and Their Therapeutic Potential for the Treatment of CNS Disorders

    Directory of Open Access Journals (Sweden)

    Richard M. Cleva

    2011-03-01

    Full Text Available Studies utilizing selective pharmacological antagonists or targeted gene deletion have demonstrated thattype 5 metabotropic glutamate receptors (mGluR5 are critical mediators and potential therapeutic targets for the treatment of numerous disorders of the central nervous system (CNS, including depression, anxiety, drug addiction, chronic pain, Fragile X syndrome, Parkinson’s disease, and gastroesophageal reflux disease. However, in recent years, the development of positive allosteric modulators (PAMs of the mGluR5 receptor have revealed that allosteric activation of this receptor may also be of potential therapeutic benefit for the treatment of other CNS disorders, including schizophrenia, cognitive deficits associated with chronic drug use, and deficits in extinction learning. Here we summarize the discovery and characterization of various mGluR5 PAMs, with an emphasis on those that are systemically active. We will also review animal studies showing that these molecules have potential efficacy as novel antipsychotic agents. Finally, we will summarize findings that suggest that mGluR5 PAMs have pro-cognitive effects such as the ability toenhance synaptic plasticity, improve performance in various learning and memory tasks, including extinction of drug-seeking behavior, and reverse cognitive deficits produced by chronic drug use.

  18. Molecular Motions as a Drug Target: Mechanistic Simulations of Anthrax Toxin Edema Factor Function Led to the Discovery of Novel Allosteric Inhibitors

    Directory of Open Access Journals (Sweden)

    Arnaud Blondel

    2012-07-01

    Full Text Available Edema Factor (EF is a component of Bacillus anthracis toxin essential for virulence. Its adenylyl cyclase activity is induced by complexation with the ubiquitous eukaryotic cellular protein, calmodulin (CaM. EF and its complexes with CaM, nucleotides and/or ions, have been extensively characterized by X-ray crystallography. Those structural data allowed molecular simulations analysis of various aspects of EF action mechanism, including the delineation of EF and CaM domains through their association energetics, the impact of calcium binding on CaM, and the role of catalytic site ions. Furthermore, a transition path connecting the free inactive form to the CaM-complexed active form of EF was built to model the activation mechanism in an attempt to define an inhibition strategy. The cavities at the surface of EF were determined for each path intermediate to identify potential sites where the binding of a ligand could block activation. A non-catalytic cavity (allosteric was found to shrink rapidly at early stages of the path and was chosen to perform virtual screening. Amongst 18 compounds selected in silico and tested in an enzymatic assay, 6 thiophen ureidoacid derivatives formed a new family of EF allosteric inhibitors with IC50 as low as 2 micromolars.

  19. Structural Bioinformatics and Protein Docking Analysis of the Molecular Chaperone-Kinase Interactions: Towards Allosteric Inhibition of Protein Kinases by Targeting the Hsp90-Cdc37 Chaperone Machinery

    Directory of Open Access Journals (Sweden)

    Gennady Verkhivker

    2013-11-01

    Full Text Available A fundamental role of the Hsp90-Cdc37 chaperone system in mediating maturation of protein kinase clients and supporting kinase functional activity is essential for the integrity and viability of signaling pathways involved in cell cycle control and organism development. Despite significant advances in understanding structure and function of molecular chaperones, the molecular mechanisms and guiding principles of kinase recruitment to the chaperone system are lacking quantitative characterization. Structural and thermodynamic characterization of Hsp90-Cdc37 binding with protein kinase clients by modern experimental techniques is highly challenging, owing to a transient nature of chaperone-mediated interactions. In this work, we used experimentally-guided protein docking to probe the allosteric nature of the Hsp90-Cdc37 binding with the cyclin-dependent kinase 4 (Cdk4 kinase clients. The results of docking simulations suggest that the kinase recognition and recruitment to the chaperone system may be primarily determined by Cdc37 targeting of the N-terminal kinase lobe. The interactions of Hsp90 with the C-terminal kinase lobe may provide additional “molecular brakes” that can lock (or unlock kinase from the system during client loading (release stages. The results of this study support a central role of the Cdc37 chaperone in recognition and recruitment of the kinase clients. Structural analysis may have useful implications in developing strategies for allosteric inhibition of protein kinases by targeting the Hsp90-Cdc37 chaperone machinery.

  20. Engineering naturally occurring trans-acting non-coding RNAs to sense molecular signals

    OpenAIRE

    Qi, Lei; Lucks, Julius B.; Liu, Chang C.; Mutalik, Vivek K.; Arkin, Adam P.

    2012-01-01

    Non-coding RNAs (ncRNAs) are versatile regulators in cellular networks. While most trans-acting ncRNAs possess well-defined mechanisms that can regulate transcription or translation, they generally lack the ability to directly sense cellular signals. In this work, we describe a set of design principles for fusing ncRNAs to RNA aptamers to engineer allosteric RNA fusion molecules that modulate the activity of ncRNAs in a ligand-inducible way in Escherichia coli. We apply these principles to nc...

  1. Communicating with Professionals

    Medline Plus

    Full Text Available ... rushed than you (or your professionals) want. Simple communication skills can help you get what you need – ... at the hospital or during office visits. Good communication skills help you get better results from the ...

  2. Communication System and Method

    Science.gov (United States)

    Sanders, Adam M. (Inventor); Strawser, Philip A. (Inventor)

    2014-01-01

    A communication system for communicating over high-latency, low bandwidth networks includes a communications processor configured to receive a collection of data from a local system, and a transceiver in communication with the communications processor. The transceiver is configured to transmit and receive data over a network according to a plurality of communication parameters. The communications processor is configured to divide the collection of data into a plurality of data streams; assign a priority level to each of the respective data streams, where the priority level reflects the criticality of the respective data stream; and modify a communication parameter of at least one of the plurality of data streams according to the priority of the at least one data stream.

  3. Communicating with Professionals

    Science.gov (United States)

    ... rushed than you (or your professionals) want. Simple communication skills can help you get what you need – over ... at the hospital or during office visits. Good communication skills help you get better results from the time ...

  4. Communicating with Professionals

    Medline Plus

    Full Text Available ... rushed than you (or your professionals) want. Simple communication skills can help you get what you need – over ... at the hospital or during office visits. Good communication skills help you get better results from the time ...

  5. Conflict Resolution Communications.

    Science.gov (United States)

    Lincoln, Melinda G.

    2002-01-01

    Suggests that, due to escalating violence in contemporary society, community colleges should offer certificate or degree programs in conflict resolution. Describes a conflict resolution communication program, which teaches communication skills, mediation processes, and coping strategies to prospective mediators. (NB)

  6. Changes in Communication Skills

    Science.gov (United States)

    Alzheimer ’s Caregiving Tips Changes in Communication Skills Communication is hard for people with Alzheimer’s disease because they have trouble remembering things. They may struggle to find words ...

  7. Communicating the seemingly unintelligible

    DEFF Research Database (Denmark)

    Chimirri, Niklas Alexander

    in an externalized objectification, in a communicative artifact. Individuals seem to particularly struggle with this non-intelligibility when living in a society which demands communicative openness, transparency, and expressive creativity. Whilst engaging in collaborative research with small...

  8. Communicating with Healthcare Professionals

    Science.gov (United States)

    ... People Change See More of Resources Communicating with Healthcare Professionals Updated:Nov 16,2015 Adapted from the National ... gained by improving communication between family caregivers and healthcare professionals. Positive outcomes include: Better care for the patient ...

  9. Communicating with Professionals

    Medline Plus

    Full Text Available ... than you (or your professionals) want. Simple communication skills can help you get what you need – over ... the hospital or during office visits. Good communication skills help you get better results from the time ...

  10. COMET communication plan

    OpenAIRE

    Real, A; Howard, B. J.; Robles, B.; Mora, J. C.; Beresford, N.A.; C. L. Barnett

    2013-01-01

    The Communication Plan for COMET is described. The goals of the Plan are to identify COMET’s various stakeholders and to develop a matrix of communication needs, delivery schedules and metrics of success.

  11. Communicating with Professionals

    Medline Plus

    Full Text Available ... Stroke More Communicating with Professionals Updated:Aug 2,2016 After a cardiac event or surgery, it is ... communication tips This content was last reviewed July 2016. Video: Recovering From Your Surgery Find helpful tips ...

  12. Communicating with Professionals

    Medline Plus

    Full Text Available ... healthcare professionals. Healthcare professionals talk about why good communication is important A patient describes how he prepares for office visits Health reporter John Hammarley summarizes communication tips This content was last reviewed July 2015. ...

  13. Diagnosis and treatment of arteriobiliary hemorrhage occurring after percutaneous biliary drainage

    International Nuclear Information System (INIS)

    Hemorrhage due to arteriobiliary communication occurred in 15 of 500 patients after percutaneous biliary drainage (PBD). Hemorrhage produced a distinct clinical syndrome and occurred sooner after PBD in patients with benign disease (eight patients, mean of 1.5 weeks) than in patients with neoplastic obstruction (seven patients, mean of 11.5 weeks). In eight patients the author identified the bleeding vessel by contrast agent injection into the transhepatic tract, and in four we were able to embolize this vessel via the transhepatic tract. Eleven patients underwent hepatic arteriography, which identified contrast agent extravasation or arterial abnormality. Angiographic embolization was possible in eight of the 11. Embolization via the transhepatic tube tract should be attempted first, with angiographic embolization as a backup

  14. Communication - Organizations’ Work Device

    OpenAIRE

    LAVINIA HULEA

    2010-01-01

    Communication represents a complex process of transmitting messages, owing to which the emitter encodes the information transmitted through a specific channel towards a receiver that will decode it. Owing to communication, organizations transmit to their customers the fact that they are capable of meeting one of their needs, of settling a problem or of offering a profit. Non-verbal and para-verbal communications usually accompany verbal communication. The importance of assimilating the forms ...

  15. Communication and Aging

    OpenAIRE

    Yorkston, Kathryn M.; Bourgeois, Michelle S.; Baylor, Carolyn R.

    2010-01-01

    Interpersonal communication has been described as a critical tool for life adjustment, linking people to their environment.1 When communication disorders are present these links can be easily broken. Communication disorders form a diverse group of conditions that vary in terms of type, severity, and co-occurrence with other symptoms that limit mobility, vision, endurance, or cognition. Although communication disorders affect people of all ages, the prevalence and complexity of these condition...

  16. Improving Communication in Design

    DEFF Research Database (Denmark)

    Maier, Anja; Doenmez, Denniz; Hepperle, Clemens;

    2011-01-01

    Communication permeates every aspect of an engineer’s work – from clarifying product specifications to shaping social ties. This paper offers an overview of recommendations from literature to improve communication within and among engineering teams. We assume communication problems are often...... of tasks. To improve these factors in order to enable effective communication, this paper collates more than hundred recommendations from journal articles and textbooks published in the fields of engineering design, management science, sociology, and psychology. Recommendations include, for example...

  17. Effective interpersonal communication

    OpenAIRE

    Darja Holátová

    2003-01-01

    Effective interpersonal communication is fundamental process. Accurate interpersonal communication between people takes place only if the idea, facts, opinions, attitudes or feelings that the sender intended to transmit are the same those understood and interpreted by the receiver. Personal feedback used by managers help personnel and managers to look at their behavior. An interpersonal communication network, the communication style aids managers to implement the objectives of the organizations.

  18. Controversy in marketing communication

    OpenAIRE

    Adámek, Petr

    2012-01-01

    Diploma thesis discusses the use of sexuality as a marketing tool in the music industry. In the first part of this work diploma thesis describes the communication theory and marketing as an essential components of marketing communication. It also analyzes marketing communication as a functional part of the marketing mix. In the second part, which is a research part, diploma thesis deals with sexuality as a controversial tool of marketing communication used in the music industry environm...

  19. Evaluation of Marketing Communication

    OpenAIRE

    Motloch, Jan

    2014-01-01

    This thesis is focused on evaluation of marketing communication. The first part of the thesis contains a theoretical base for the topics marketing and marketing communication, especially evaluation of marketing communication is described more in depth. Chosen methods of evaluation described in the theoretical part are used in the practical part of the thesis, which deals with the evaluation of marketing communication that was carried out during the introduction of an industrial automation pro...

  20. Energy and scientific communication

    OpenAIRE

    De Sanctis E.

    2013-01-01

    Energy communication is a paradigmatic case of scientific communication. It is particularly important today, when the world is confronted with a number of immediate, urgent problems. Science communication has become a real duty and a big challenge for scientists. It serves to create and foster a climate of reciprocal knowledge and trust between science and society, and to establish a good level of interest and enthusiasm for research. For an effective communication it is important to establis...

  1. Communication Strategy of Company

    OpenAIRE

    Broklová, Jaroslava

    2014-01-01

    The main subject of the thesis "Communication strategy of company" is analyzing the current state of the communication mix, based of the analysis result and marketing re-search to design a suitable communication mix. The thesis is divided into three main parts. The first part focuses on the theoretical interpretation and definition of important marketing concepts, communication mix, marketing environment and marketing re-search. The second part introduces basic information about reconditionin...

  2. Teacher's communication skills

    OpenAIRE

    ZIKLOVÁ, Hana

    2010-01-01

    This diploma thesis concerns the area of self-presentation of a teacher and effective use of his communication skills. The thesis is divided into two parts. The first part is theoretical and presents basic concepts of social communication and defines communication skills essential for effective teaching. The practical part is partly based on the output of a questionnaire survey where the author probes knowledge of communication skills of students of pedagogical faculty and how they evaluate t...

  3. Allosteric regulation of 6-phosphofructo-1-kinase activity of fat body and flight muscle from the bloodsucking bug Rhodnius prolixus

    Directory of Open Access Journals (Sweden)

    Gutemberg G. Alves

    2007-03-01

    Full Text Available 6-phosphofructo-1-kinase (phosphofructokinase; PFK activity from Rhodnius prolixus, a haematophagous insect which is usually a poor flyer, was measured and compared in two metabolically active tissues - flight muscle and fat body. The activity of this important regulatory glycolytic enzyme was much more pronounced in muscle (15.1 ± 1.4 U/mg than in fat body extracts (3.6±0.4 U/mg, although the latter presented higher levels of enzyme per protein content, as measured by western-blotting. Muscle extracts are more responsible than fat body to ATP and fructose 6-phosphate, both substrates of PFK. Allosteric regulation exerted by different effectors such as ADP, AMP and fructose 2,6-phosphate presented a singular pattern for each tissue. Optimal pH (8.0-8.5 and sensitivity to pH variation was very similar, and citrate was unable to inhibit PFK activity in both extracts. Our results suggest the existence of a particular PFK activity for each tissue, with regulatory patterns that are consistent with their physiological roles.A atividade da fosfofrutocinase (PFK de Rodnius prolixus, um inseto hematófago, o qual vôa somente pequenas distâncias, foi medida e comparada em dois tecidos metabolicamente ativos - músculo de asa e corpo gorduroso. A atividade desta importante enzima glicolítica regulatória foi muito mais pronunciada em músculo de asa (15,1 ±1,4 U/mg do que em extrato de corpo gorduroso (3,6 ±0,4 U/mg embora este último tenha apresentado níveis mais altos da enzima por quantidade de proteína, como medido por western-blotting. Extratos de músculo foram mais responsivos do que corpo gorduroso para ATP e frutose-6-fosfato, ambos substratos da PFK. A regulação alostérica exercida por diferentes efetores tais como ADP, AMP, frutose-2,6-bisfosfato apresentou um padrão singular para cada tecido. O pH ótimo (8,0-8,5 e a sensibilidade a variações de pH, foram muito similares e o citrato foi incapaz de inibir a atividade da PFK em

  4. When Does A Gait Transition Occur During Human Locomotion?

    OpenAIRE

    Alan Hreljac; Rodney T. Imamura; Escamilla, Rafael F.; Brent Edwards, W.

    2007-01-01

    When a treadmill accelerates continuously, the walk-run transition has generally been assumed to occur at the instant when a flight phase is first observed, while the run-walk transition has been assumed to occur at the instant of the first double support period. There is no theoretical or empirical evidence to suggest that gait transitions occur at the instant of these events, nor even whether transitions are abrupt events. The purpose of this study was to determine whether the gait transiti...

  5. Communication Policies in Yugoslavia.

    Science.gov (United States)

    Lekovic, Zdravko; Bjelica, Mihalo

    This report on communication policies in Yugoslavia is part of a larger project, sponsored by UNESCO and intended to analyze communication policies as they exist at public, institutional, and professional levels in selected countries. Included in this report are: (1) the premise of Yugoslavian communication policy; (2) historical development of…

  6. Communication Games in Print.

    Science.gov (United States)

    Schneiderman, Ellen

    1990-01-01

    This article presents a rationale and ways to use communication games in written form to entice deaf children to try new forms of language. It emphasizes the importance of using communicative teaching methods and considering students' communicative adequacy rather than form. Games include picture/object matching games and bingo/lotto games. (JDD)

  7. Developing Oral Communication Skills.

    Science.gov (United States)

    Washington Office of the State Superintendent of Public Instruction, Olympia.

    Intended for use by both elementary and secondary school teachers, the two papers in this report stress the importance of developing students' oral and written communication skills. The first paper, "Relationship of Oral Communication to Reading," by Phil Backlund and John Johnson, argues that ability in oral communication is a prerequisite to the…

  8. Communication and Your Newborn

    Science.gov (United States)

    ... Story" 5 Things to Know About Zika & Pregnancy Communication and Your Newborn KidsHealth > For Parents > Communication and Your Newborn Print A A A Text ... first smile — a welcome addition to your baby's communication skills! continue What Should I Do? As soon ...

  9. CSR communication: quo vadis?

    NARCIS (Netherlands)

    U. Golob; K. Podnar; W.J. Elving; A. Ellerup Nielsen; C. Thomsen; F. Schultz

    2013-01-01

    Purpose - This paper aims to introduce the special issue on CSR communication attached to the First International CSR Communication Conference held in Amsterdam in October 2011. The aim of the introduction is also to review CSR communication papers published in scholarly journals in order to make a

  10. Language, Perception, Culture & Communication

    Institute of Scientific and Technical Information of China (English)

    DU Man-li

    2015-01-01

    The paper explores the prospect of introducing language, perception, culture and communication. Starting with some definitions of language, perception, culture and communication, the paper argues for the internal connection among them. It pro⁃vides better understanding of these factors in foreign language learning and encourages learners to achieve the better learning re⁃sult to communicate effectively through language, culture etc.

  11. ORGANIZATIONAL RISK COMMUNICATION

    Science.gov (United States)

    Ris communication tools in organizations differs in several ways from many of tools and techniques developed for public meetings. The traditional view of risk communication seeks to manage the public outrage ssociated with site-based issues. Organizational risk communication seek...

  12. Modes of Communication

    Science.gov (United States)

    Dewatripont, Mathias; Tirole, Jean

    2005-01-01

    The paper develops a theory of costly communication in which the sender's and receiver's motivations and abilities endogenously determine the communication mode and the transfer of knowledge. Communication is modeled as a problem of moral hazard in teams, in which the sender and receiver select persuasion and message elaboration efforts. The model…

  13. Intercultural Communicative Case Study

    Institute of Scientific and Technical Information of China (English)

    吴冬梅

    2009-01-01

    The essay is mainly about the author's comprehension of cultural differences and intercultural communication after reading the book Communication Between Cultures.In addition,the author also analyses three cases with the theories and approaches mentioned in Communication Between Cultures.

  14. Comparative Toxicology of Libby Amphibole and Naturally Occurring Asbestos

    Science.gov (United States)

    Summary sentence: Comparative toxicology of Libby amphibole (LA) and site-specific naturally occurring asbestos (NOA) provides new insights on physical properties influencing health effects and mechanisms of asbestos-induced inflammation, fibrosis, and tumorigenesis.Introduction/...

  15. Unilateral eruptive vellus hair cysts occurring on the face.

    Science.gov (United States)

    Lew, B-L; Lee, M-H; Haw, C-R

    2006-11-01

    Eruptive vellus hair cysts (EVHC) are small, cystic papules that usually occur on the chest and extremities. Their aetiology is unknown. Fewer than 10 cases of a variant form of EVHC that occur exclusively on the face have been reported. We describe a case of EVHC limited to the right side of the face. To the best of our knowledge, no case of unilateral EVHC has been reported. PMID:17062051

  16. Internet Censorship in China: Where Does the Filtering Occur?

    Science.gov (United States)

    Xu, Xueyang; Mao, Z. Morley; Halderman, J. Alex

    China filters Internet traffic in and out of the country. In order to circumvent the firewall, it is helpful to know where the filtering occurs. In this work, we explore the AS-level topology of China's network, and probe the firewall to find the locations of filtering devices. We find that even though most filtering occurs in border ASes, choke points also exist in many provincial networks. The result suggests that two major ISPs in China have different approaches placing filtering devices.

  17. 3-(Imidazolyl methyl)-3-aza-bicyclo[3.1.0]hexan-6-yl)methyl ethers: a novel series of mGluR2 positive allosteric modulators.

    Science.gov (United States)

    Zhang, Lei; Rogers, Bruce N; Duplantier, Allen J; McHardy, Stanley F; Efremov, Ivan; Berke, Helen; Qian, Weimin; Zhang, Andy Q; Maklad, Noha; Candler, John; Doran, Angela C; Lazzaro, John T; Ganong, Alan H

    2008-10-15

    The synthesis and structure-activity relationship (SAR) of a novel series of 3-(imidazolyl methyl)-3-aza-bicyclo[3.1.0]hexan-6-yl)methyl ethers, derived from a high throughput screening (HTS), are described. Subsequent optimization led to identification of potent, metabolically stable and orally available mGluR2 positive allosteric modulators (PAMs). PMID:18812259

  18. COMMUNICATION - ORGANIZATIONS’ WORK DEVICE

    Directory of Open Access Journals (Sweden)

    LAVINIA HULEA

    2010-01-01

    Full Text Available Communication represents a complex process of transmitting messages, owing to which the emitter encodes the information transmitted through a specific channel towards a receiver that will decode it. Owing to communication, organizations transmit to their customers the fact that they are capable of meeting one of their needs, of settling a problem or of offering a profit. Non-verbal and para-verbal communications usually accompany verbal communication. The importance of assimilating the forms of communication is, at an organizational level, a complex device that determines the mastering of certain techniques, procedures, and algorithms of encoding and decoding intricate messages transmitted through various channels.

  19. Absolutely covert quantum communication

    CERN Document Server

    Bradler, Kamil; Siopsis, George; Weedbrook, Christian

    2016-01-01

    We present truly ultimate limits on covert quantum communication by exploiting quantum-mechanical properties of the Minkowski vacuum in the quantum field theory framework. Our main results are the following: We show how two parties equipped with Unruh-DeWitt detectors can covertly communicate at large distances without the need of hiding in a thermal background or relying on various technological tricks. We reinstate the information-theoretic security standards for reliability of asymptotic quantum communication and show that the rate of covert communication is strictly positive. Therefore, contrary to the previous conclusions, covert and reliable quantum communication is possible.

  20. Conceptual Model for Communication

    CERN Document Server

    Fedaghi, Sabah Al; Fadel, Zahraa

    2009-01-01

    A variety of idealized models of communication systems exist, and all may have something in common. Starting with Shannons communication model and ending with the OSI model, this paper presents progressively more advanced forms of modeling of communication systems by tying communication models together based on the notion of flow. The basic communication process is divided into different spheres (sources, channels, and destinations), each with its own five interior stages, receiving, processing, creating, releasing, and transferring of information. The flow of information is ontologically distinguished from the flow of physical signals, accordingly, Shannons model, network based OSI models, and TCP IP are redesigned.