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Sample records for dna polymerase pol

  1. Involvement of specialized DNA polymerases Pol II, Pol IV and DnaE2 in DNA replication in the absence of Pol I in Pseudomonas putida

    International Nuclear Information System (INIS)

    Sidorenko, Julia; Jatsenko, Tatjana; Saumaa, Signe; Teras, Riho; Tark-Dame, Mariliis; Horak, Rita; Kivisaar, Maia

    2011-01-01

    The majority of bacteria possess a different set of specialized DNA polymerases than those identified in the most common model organism Escherichia coli. Here, we have studied the ability of specialized DNA polymerases to substitute Pol I in DNA replication in Pseudomonas putida. Our results revealed that P. putida Pol I-deficient cells have severe growth defects in LB medium, which is accompanied by filamentous cell morphology. However, growth of Pol I-deficient bacteria on solid rich medium can be restored by reduction of reactive oxygen species in cells. Also, mutants with improved growth emerge rapidly. Similarly to the initial Pol I-deficient P. putida, its adapted derivatives express a moderate mutator phenotype, which indicates that DNA replication carried out in the absence of Pol I is erroneous both in the original Pol I-deficient bacteria and the adapted derivatives. Analysis of the spectra of spontaneous Rif r mutations in P. putida strains lacking different DNA polymerases revealed that the presence of specialized DNA polymerases Pol II and Pol IV influences the frequency of certain base substitutions in Pol I-proficient and Pol I-deficient backgrounds in opposite ways. Involvement of another specialized DNA polymerase DnaE2 in DNA replication in Pol I-deficient bacteria is stimulated by UV irradiation of bacteria, implying that DnaE2-provided translesion synthesis partially substitutes the absence of Pol I in cells containing heavily damaged DNA.

  2. Characterization of Mycobacterium smegmatis PolD2 and PolD1 as RNA/DNA polymerases homologous to the POL domain of bacterial DNA ligase D.

    Science.gov (United States)

    Zhu, Hui; Bhattarai, Hitesh; Yan, Han-Guang; Shuman, Stewart; Glickman, Michael S

    2012-12-21

    Mycobacteria exploit nonhomologous end-joining (NHEJ) to repair DNA double-strand breaks. The core NHEJ machinery comprises the homodimeric DNA end-binding protein Ku and DNA ligase D (LigD), a modular enzyme composed of a C-terminal ATP-dependent ligase domain (LIG), a central 3'-phosphoesterase domain (PE), and an N-terminal polymerase domain (POL). LigD POL is proficient at adding templated and nontemplated deoxynucleotides and ribonucleotides to DNA ends in vitro and is the catalyst in vivo of unfaithful NHEJ events involving nontemplated single-nucleotide additions to blunt DSB ends. Here, we identify two mycobacterial proteins, PolD1 and PolD2, as stand-alone homologues of the LigD POL domain. Biochemical characterization of PolD1 and PolD2 shows that they resemble LigD POL in their monomeric quaternary structures, their ability to add templated and nontemplated nucleotides to primer-templates and blunt ends, and their preference for rNTPs versus dNTPs. Deletion of polD1, polD2, or both from a Mycobacterium smegmatis strain carrying an inactivating mutation in LigD POL failed to reveal a role for PolD1 or PolD2 in templated nucleotide additions during NHEJ of 5'-overhang DSBs or in clastogen resistance. Whereas our results document the existence and characteristics of new stand-alone members of the LigD POL family of RNA/DNA polymerases, they imply that other polymerases can perform fill-in synthesis during mycobacterial NHEJ.

  3. Roles of Saccharomyces cerevisiae DNA polymerases Polη and Polζ in response to irradiation by simulated sunlight

    Science.gov (United States)

    Kozmin, Stanislav G.; Pavlov, Youri I.; Kunkel, Thomas A.; Sage, Evelyne

    2003-01-01

    Sunlight causes lesions in DNA that if unrepaired and inaccurately replicated by DNA polymerases yield mutations that result in skin cancer in humans. Two enzymes involved in translesion synthesis (TLS) of UV-induced photolesions are DNA polymerase η (Polη) and polymerase ζ (Polζ), encoded by the RAD30A and REV3 genes, respectively. Previous studies have investigated the TLS roles of these polymerases in human and yeast cells irradiated with monochromatic, short wavelength UVC radiation (254 nm). However, less is known about cellular responses to solar radiation, which is of higher and mixed wavelengths (310–1100 nm) and produces a different spectrum of DNA lesions, including Dewar photoproducts and oxidative lesions. Here we report on the comparative cytotoxic and mutagenic effects of simulated sunlight (SSL) and UVC radiation on yeast wild-type, rad30Δ, rev3Δ and rev3Δ rad30Δ strains. The results with SSL support several previous interpretations on the roles of these two polymerases in TLS of photodimers and (6–4) photoproducts derived from studies with UVC. They further suggest that Polη participates in the non-mutagenic bypass of SSL-dependent cytosine-containing Dewar photoproducts and 8-oxoguanine, while Polζ is mainly responsible for the mutagenic bypass of all types of Dewar photoproducts. They also suggest that in the absence of Polζ, Polη contributes to UVC- and SSL-induced mutagenesis, possibly by the bypass of photodimers containing deaminated cytosine. PMID:12888515

  4. Bacillus subtilis DNA polymerases, PolC and DnaE, are required for both leading and lagging strand synthesis in SPP1 origin-dependent DNA replication

    Science.gov (United States)

    Seco, Elena M.

    2017-01-01

    Abstract Firmicutes have two distinct replicative DNA polymerases, the PolC leading strand polymerase, and PolC and DnaE synthesizing the lagging strand. We have reconstituted in vitro Bacillus subtilis bacteriophage SPP1 θ-type DNA replication, which initiates unidirectionally at oriL. With this system we show that DnaE is not only restricted to lagging strand synthesis as previously suggested. DnaG primase and DnaE polymerase are required for initiation of DNA replication on both strands. DnaE and DnaG synthesize in concert a hybrid RNA/DNA ‘initiation primer’ on both leading and lagging strands at the SPP1 oriL region, as it does the eukaryotic Pol α complex. DnaE, as a RNA-primed DNA polymerase, extends this initial primer in a reaction modulated by DnaG and one single-strand binding protein (SSB, SsbA or G36P), and hands off the initiation primer to PolC, a DNA-primed DNA polymerase. Then, PolC, stimulated by DnaG and the SSBs, performs the bulk of DNA chain elongation at both leading and lagging strands. Overall, these modulations by the SSBs and DnaG may contribute to the mechanism of polymerase switch at Firmicutes replisomes. PMID:28575448

  5. Distinct co-evolution patterns of genes associated to DNA polymerase III DnaE and PolC

    Directory of Open Access Journals (Sweden)

    Engelen Stefan

    2012-02-01

    Full Text Available Abstract Background Bacterial genomes displaying a strong bias between the leading and the lagging strand of DNA replication encode two DNA polymerases III, DnaE and PolC, rather than a single one. Replication is a highly unsymmetrical process, and the presence of two polymerases is therefore not unexpected. Using comparative genomics, we explored whether other processes have evolved in parallel with each polymerase. Results Extending previous in silico heuristics for the analysis of gene co-evolution, we analyzed the function of genes clustering with dnaE and polC. Clusters were highly informative. DnaE co-evolves with the ribosome, the transcription machinery, the core of intermediary metabolism enzymes. It is also connected to the energy-saving enzyme necessary for RNA degradation, polynucleotide phosphorylase. Most of the proteins of this co-evolving set belong to the persistent set in bacterial proteomes, that is fairly ubiquitously distributed. In contrast, PolC co-evolves with RNA degradation enzymes that are present only in the A+T-rich Firmicutes clade, suggesting at least two origins for the degradosome. Conclusion DNA replication involves two machineries, DnaE and PolC. DnaE co-evolves with the core functions of bacterial life. In contrast PolC co-evolves with a set of RNA degradation enzymes that does not derive from the degradosome identified in gamma-Proteobacteria. This suggests that at least two independent RNA degradation pathways existed in the progenote community at the end of the RNA genome world.

  6. Dideoxynucleoside triphosphate-sensitive DNA polymerase from rice is involved in base excision repair and immunologically similar to mammalian DNA pol beta.

    Science.gov (United States)

    Sarkar, Sailendra Nath; Bakshi, Sankar; Mokkapati, Sanath K; Roy, Sujit; Sengupta, Dibyendu N

    2004-07-16

    A single polypeptide with ddNTP-sensitive DNA polymerase activity was purified to near homogeneity from the shoot tips of rice seedlings and analysis of the preparations by SDS-PAGE followed by silver staining showed a polypeptide of 67 kDa size. The DNA polymerase activity was found to be inhibitory by ddNTP in both in vitro DNA polymerase activity assay and activity gel analysis. Aphidicolin, an inhibitor of other types of DNA polymerases, had no effect on plant enzyme. The 67 kDa rice DNA polymerase was found to be recognized by the polyclonal antibody (purified IgG) made against rat DNA polymerase beta (pol beta) both in solution and also on Western blot. The recognition was found to be very specific as the activity of Klenow enzyme was unaffected by the antibody. The ability of rice nuclear extract to correct G:U mismatch of oligo-duplex was observed when oligo-duplex with 32P-labeled lower strand containing U (at 22nd position) was used as substrate. Differential appearance of bands at 21-mer, 22-mer, and 51-mer position in presence of dCTP was visible only with G:U mismatch oligo-duplex, but not with G:C oligo-duplex. While ddCTP or polyclonal antibody against rat-DNA pol beta inhibits base excision repair (BER), aphidicolin had no effect. These results for the first time clearly demonstrate the ability of rice nuclear extract to run BER and the involvement of ddNTP-sensitive pol beta type DNA polymerase. Immunological similarity of the ddNTP-sensitive DNA polymerase beta of rice and rat and its involvement in BER revealed the conservation of structure and function of ddNTP-sensitive DNA pol beta in plant and animal.

  7. DNA polymerase iota (Pol ι) promotes invasion and metastasis of esophageal squamous cell carcinoma.

    Science.gov (United States)

    Zou, Shitao; Shang, Zeng-Fu; Liu, Biao; Zhang, Shuyu; Wu, Jinchang; Huang, Min; Ding, Wei-Qun; Zhou, Jundong

    2016-05-31

    DNA polymerase iota (Pol ι) is an error-prone DNA polymerase involved in translesion DNA synthesis (TLS) that contributes to the accumulation of DNA mutations. We recently showed that Pol ι is overexpressed in human esophageal squamous cell cancer (ESCC) tissues which promotes ESCC' progression. The present study was aimed at investigating the molecular mechanisms by which Pol ι enhances the invasiveness and metastasis of ESCC cells. We found that the expression of Pol ι is significantly higher in ESCCs with lymph node metastasis compared to those without lymph node metastasis. Kaplan-Meier analysis revealed an inverse correlation between Pol ι expression and patient prognosis. The expression levels of matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9), two essential regulators of cells' invasiveness, were positively associated with Pol ι expression in ESCC tissues. Ectopic expression of Pol ι enhanced the motility and invasiveness of ESCC cells as evaluated by wound-healing and transwell assays, respectively. A xenograft nude mouse model showed that Pol ι promotes the colonization of ESCC cells in the liver, lung and kidney. Signaling pathway analysis identified the JNK-AP-1 cascade as a mediator of the Pol ι-induced increase in the expression of MMP-2/9 and enhancement of ESCC progression. These data demonstrate the underlying mechanism by which Pol ι promotes ESCC progression, suggesting that Pol ι is a potential novel prognostic biomarker and therapeutic target for ESCC.

  8. Structure and function of DNA polymerase μ

    International Nuclear Information System (INIS)

    Matsumoto, Takuro; Maezawa, So

    2013-01-01

    DNA polymerases are enzymes playing the central role in DNA metabolism, including DNA replication, DNA repair and recombination. DNA polymerase μ (pol μ DNA polymerase λ (pol λ) and terminal deoxynucleotidyltransferase (TdT) in X family DNA polymerases function in non-homologous end-joining (NHEJ), which is the predonmiant repair pathway for DNA double-strand breaks (DSBs). NHEJ involves enzymes that capture both ends of the broken DNA strand, bring them together in a synaptic DNA-protein complex, and repair the DSB. Pol μ and pol λ fill in the gaps at the junction to maintain the genomic integrity. TdT synthesizes N region at the junction during V(D)J recombination and promotes diversity of immunoglobulin or T-cell receptor gene. Among these three polymerases, the regulatory mechanisms of pol μ remain rather unclear. We have approached the mechanism of pol μ from both sides of structure and cellular dynamics. Here, we propose some new insights into pol μ and the probable NHEJ model including our findings. (author)

  9. DNA repair in DNA-polymerase-deficient mutants of Escherichia coli

    International Nuclear Information System (INIS)

    Smith, D.W.; Tait, R.C.; Harris, A.L.

    1975-01-01

    Escherichia coli mutants deficient in DNA polymerase I, in DNA polymerases I and II, or in DNA polymerase III can efficiently and completely execute excision-repair and postreplication repair of the uv-damaged DNA at 30 0 C and 43 0 C when assayed by alkaline sucrose gradients. Repair by Pol I - and Pol I - , Pol II - cells is inhibited by 1-β-D-arabinofuranosylcytosine (araC) at 43 0 C but not at 30 0 C, whereas that by Pol III - cells is insensitive to araC at any temperature. Thus, either Pol I or Pol III is required for complete and efficient repair, and in their absence Pol II mediates a limited, incomplete dark repair of uv-damaged DNA

  10. Structure of human DNA polymerase iota and the mechanism of DNA synthesis.

    Science.gov (United States)

    Makarova, A V; Kulbachinskiy, A V

    2012-06-01

    Cellular DNA polymerases belong to several families and carry out different functions. Highly accurate replicative DNA polymerases play the major role in cell genome replication. A number of new specialized DNA polymerases were discovered at the turn of XX-XXI centuries and have been intensively studied during the last decade. Due to the special structure of the active site, these enzymes efficiently perform synthesis on damaged DNA but are characterized by low fidelity. Human DNA polymerase iota (Pol ι) belongs to the Y-family of specialized DNA polymerases and is one of the most error-prone enzymes involved in DNA synthesis. In contrast to other DNA polymerases, Pol ι is able to use noncanonical Hoogsteen interactions for nucleotide base pairing. This allows it to incorporate nucleotides opposite various lesions in the DNA template that impair Watson-Crick interactions. Based on the data of X-ray structural analysis of Pol ι in complexes with various DNA templates and dNTP substrates, we consider the structural peculiarities of the Pol ι active site and discuss possible mechanisms that ensure the unique behavior of the enzyme on damaged and undamaged DNA.

  11. DNA polymerase beta participates in mitochondrial DNA repair

    DEFF Research Database (Denmark)

    Sykora, P; Kanno, S; Akbari, M

    2017-01-01

    We have detected DNA polymerase beta (Polβ), known as a key nuclear base excision repair (BER) protein, in mitochondrial protein extracts derived from mammalian tissue and cells. Manipulation of the N-terminal sequence affected the amount of Polβ in the mitochondria. Using Polβ fragments, mitocho......We have detected DNA polymerase beta (Polβ), known as a key nuclear base excision repair (BER) protein, in mitochondrial protein extracts derived from mammalian tissue and cells. Manipulation of the N-terminal sequence affected the amount of Polβ in the mitochondria. Using Polβ fragments......, mitochondrial-specific protein partners were identified, with the interactors mainly functioning in DNA maintenance and mitochondrial import. Of particular interest was the identification of the proteins TWINKLE, SSBP1 and TFAM, all of which are mitochondria specific DNA effectors and are known to function...... in the nucleoid. Polβ directly interacted with, and influenced the activity of, the mitochondrial helicase TWINKLE. Human kidney cells with Polβ knock-out (KO) had higher endogenous mtDNA damage. Mitochondrial extracts derived from heterozygous Polβ mouse tissue and KO cells had lower nucleotide incorporation...

  12. Translesion DNA polymerases Pol ζ, Pol η, Pol ι, Pol κ and Rev1 are ...

    Indian Academy of Sciences (India)

    MADU

    Specialized DNA polymerases called translesion polymerases are among the major determinants of spontaneous and DNA damage-induced mutation in both prokaryotes and eukaryotes. (Livneh 2001). The classical replicative DNA polymerases can synthesize DNA with remarkable efficiency and fidelity.

  13. Replicative DNA polymerase mutations in cancer☆

    Science.gov (United States)

    Heitzer, Ellen; Tomlinson, Ian

    2014-01-01

    Three DNA polymerasesPol α, Pol δ and Pol ɛ — are essential for DNA replication. After initiation of DNA synthesis by Pol α, Pol δ or Pol ɛ take over on the lagging and leading strand respectively. Pol δ and Pol ɛ perform the bulk of replication with very high fidelity, which is ensured by Watson–Crick base pairing and 3′exonuclease (proofreading) activity. Yeast models have shown that mutations in the exonuclease domain of Pol δ and Pol ɛ homologues can cause a mutator phenotype. Recently, we identified germline exonuclease domain mutations (EDMs) in human POLD1 and POLE that predispose to ‘polymerase proofreading associated polyposis’ (PPAP), a disease characterised by multiple colorectal adenomas and carcinoma, with high penetrance and dominant inheritance. Moreover, somatic EDMs in POLE have also been found in sporadic colorectal and endometrial cancers. Tumors with EDMs are microsatellite stable and show an ‘ultramutator’ phenotype, with a dramatic increase in base substitutions. PMID:24583393

  14. Mitochondrial DNA replication: a PrimPol perspective

    Science.gov (United States)

    Bailey, Laura J.

    2017-01-01

    PrimPol, (primase–polymerase), the most recently identified eukaryotic polymerase, has roles in both nuclear and mitochondrial DNA maintenance. PrimPol is capable of acting as a DNA polymerase, with the ability to extend primers and also bypass a variety of oxidative and photolesions. In addition, PrimPol also functions as a primase, catalysing the preferential formation of DNA primers in a zinc finger-dependent manner. Although PrimPol's catalytic activities have been uncovered in vitro, we still know little about how and why it is targeted to the mitochondrion and what its key roles are in the maintenance of this multicopy DNA molecule. Unlike nuclear DNA, the mammalian mitochondrial genome is circular and the organelle has many unique proteins essential for its maintenance, presenting a differing environment within which PrimPol must function. Here, we discuss what is currently known about the mechanisms of DNA replication in the mitochondrion, the proteins that carry out these processes and how PrimPol is likely to be involved in assisting this vital cellular process. PMID:28408491

  15. PCNA mono-ubiquitination and activation of translesion DNA polymerases by DNA polymerase {alpha}.

    Science.gov (United States)

    Suzuki, Motoshi; Niimi, Atsuko; Limsirichaikul, Siripan; Tomida, Shuta; Miao Huang, Qin; Izuta, Shunji; Usukura, Jiro; Itoh, Yasutomo; Hishida, Takashi; Akashi, Tomohiro; Nakagawa, Yoshiyuki; Kikuchi, Akihiko; Pavlov, Youri; Murate, Takashi; Takahashi, Takashi

    2009-07-01

    Translesion DNA synthesis (TLS) involves PCNA mono-ubiquitination and TLS DNA polymerases (pols). Recent evidence has shown that the mono-ubiquitination is induced not only by DNA damage but also by other factors that induce stalling of the DNA replication fork. We studied the effect of spontaneous DNA replication errors on PCNA mono-ubiquitination and TLS induction. In the pol1L868F strain, which expressed an error-prone pol alpha, PCNA was spontaneously mono-ubiquitinated. Pol alpha L868F had a rate-limiting step at the extension from mismatched primer termini. Electron microscopic observation showed the accumulation of a single-stranded region at the DNA replication fork in yeast cells. For pol alpha errors, pol zeta participated in a generation of +1 frameshifts. Furthermore, in the pol1L868F strain, UV-induced mutations were lower than in the wild-type and a pol delta mutant strain (pol3-5DV), and deletion of the RAD30 gene (pol eta) suppressed this defect. These data suggest that nucleotide misincorporation by pol alpha induces exposure of single-stranded DNA, PCNA mono-ubiquitination and activates TLS pols.

  16. Replicative DNA polymerase mutations in cancer.

    Science.gov (United States)

    Heitzer, Ellen; Tomlinson, Ian

    2014-02-01

    Three DNA polymerases - Pol α, Pol δ and Pol ɛ - are essential for DNA replication. After initiation of DNA synthesis by Pol α, Pol δ or Pol ɛ take over on the lagging and leading strand respectively. Pol δ and Pol ɛ perform the bulk of replication with very high fidelity, which is ensured by Watson-Crick base pairing and 3'exonuclease (proofreading) activity. Yeast models have shown that mutations in the exonuclease domain of Pol δ and Pol ɛ homologues can cause a mutator phenotype. Recently, we identified germline exonuclease domain mutations (EDMs) in human POLD1 and POLE that predispose to 'polymerase proofreading associated polyposis' (PPAP), a disease characterised by multiple colorectal adenomas and carcinoma, with high penetrance and dominant inheritance. Moreover, somatic EDMs in POLE have also been found in sporadic colorectal and endometrial cancers. Tumors with EDMs are microsatellite stable and show an 'ultramutator' phenotype, with a dramatic increase in base substitutions. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  17. Isolation and characterization of high affinity aptamers against DNA polymerase iota.

    Science.gov (United States)

    Lakhin, Andrei V; Kazakov, Andrei A; Makarova, Alena V; Pavlov, Yuri I; Efremova, Anna S; Shram, Stanislav I; Tarantul, Viacheslav Z; Gening, Leonid V

    2012-02-01

    Human DNA-polymerase iota (Pol ι) is an extremely error-prone enzyme and the fidelity depends on the sequence context of the template. Using the in vitro systematic evolution of ligands by exponential enrichment (SELEX) procedure, we obtained an oligoribonucleotide with a high affinity to human Pol ι, named aptamer IKL5. We determined its dissociation constant with homogenous preparation of Pol ι and predicted its putative secondary structure. The aptamer IKL5 specifically inhibits DNA-polymerase activity of the purified enzyme Pol ι, but did not inhibit the DNA-polymerase activities of human DNA polymerases beta and kappa. IKL5 suppressed the error-prone DNA-polymerase activity of Pol ι also in cellular extracts of the tumor cell line SKOV-3. The aptamer IKL5 is useful for studies of the biological role of Pol ι and as a potential drug to suppress the increase of the activity of this enzyme in malignant cells.

  18. Efficiency and Fidelity of Human DNA Polymerases λ and β during Gap-Filling DNA Synthesis

    Science.gov (United States)

    Brown, Jessica A.; Pack, Lindsey R.; Sanman, Laura E.; Suo, Zucai

    2010-01-01

    The base excision repair (BER) pathway coordinates the replacement of 1 to 10 nucleotides at sites of single-base lesions. This process generates DNA substrates with various gap sizes which can alter the catalytic efficiency and fidelity of a DNA polymerase during gap-filling DNA synthesis. Here, we quantitatively determined the substrate specificity and base substitution fidelity of human DNA polymerase λ (Pol λ), an enzyme proposed to support the known BER DNA polymerase β (Pol β), as it filled 1- to 10-nucleotide gaps at 1-nucleotide intervals. Pol λ incorporated a correct nucleotide with relatively high efficiency until the gap size exceeded 9 nucleotides. Unlike Pol λ, Pol β did not have an absolute threshold on gap size as the catalytic efficiency for a correct dNTP gradually decreased as the gap size increased from 2 to 10 nucleotides and then recovered for non-gapped DNA. Surprisingly, an increase in gap size resulted in lower polymerase fidelity for Pol λ, and this downregulation of fidelity was controlled by its non-enzymatic N-terminal domains. Overall, Pol λ was up to 160-fold more error-prone than Pol β, thereby suggesting Pol λ would be more mutagenic during long gap-filling DNA synthesis. In addition, dCTP was the preferred misincorporation for Pol λ and its N-terminal domain truncation mutants. This nucleotide preference was shown to be dependent upon the identity of the adjacent 5′-template base. Our results suggested that both Pol λ and Pol β would catalyze nucleotide incorporation with the highest combination of efficiency and accuracy when the DNA substrate contains a single-nucleotide gap. Thus, Pol λ, like Pol β, is better suited to catalyze gap-filling DNA synthesis during short-patch BER in vivo, although, Pol λ may play a role in long-patch BER. PMID:20961817

  19. Both DNA Polymerases δ and ε Contact Active and Stalled Replication Forks Differently

    Science.gov (United States)

    Yu, Chuanhe; Gan, Haiyun

    2017-01-01

    ABSTRACT Three DNA polymerases, polymerases α, δ, and ε (Pol α, Pol δ, and Pol ε), are responsible for eukaryotic genome duplication. When DNA replication stress is encountered, DNA synthesis stalls until the stress is ameliorated. However, it is not known whether there is a difference in the association of each polymerase with active and stalled replication forks. Here, we show that each DNA polymerase has a distinct pattern of association with active and stalled replication forks. Pol α is enriched at extending Okazaki fragments of active and stalled forks. In contrast, although Pol δ contacts the nascent lagging strands of active and stalled forks, it binds to only the matured (and not elongating) Okazaki fragments of stalled forks. Pol ε has greater contact with the nascent single-stranded DNA (ssDNA) of the leading strand on active forks than on stalled forks. We propose that the configuration of DNA polymerases at stalled forks facilitates the resumption of DNA synthesis after stress removal. PMID:28784720

  20. Interactions and Localization of Escherichia coli Error-Prone DNA Polymerase IV after DNA Damage.

    Science.gov (United States)

    Mallik, Sarita; Popodi, Ellen M; Hanson, Andrew J; Foster, Patricia L

    2015-09-01

    Escherichia coli's DNA polymerase IV (Pol IV/DinB), a member of the Y family of error-prone polymerases, is induced during the SOS response to DNA damage and is responsible for translesion bypass and adaptive (stress-induced) mutation. In this study, the localization of Pol IV after DNA damage was followed using fluorescent fusions. After exposure of E. coli to DNA-damaging agents, fluorescently tagged Pol IV localized to the nucleoid as foci. Stepwise photobleaching indicated ∼60% of the foci consisted of three Pol IV molecules, while ∼40% consisted of six Pol IV molecules. Fluorescently tagged Rep, a replication accessory DNA helicase, was recruited to the Pol IV foci after DNA damage, suggesting that the in vitro interaction between Rep and Pol IV reported previously also occurs in vivo. Fluorescently tagged RecA also formed foci after DNA damage, and Pol IV localized to them. To investigate if Pol IV localizes to double-strand breaks (DSBs), an I-SceI endonuclease-mediated DSB was introduced close to a fluorescently labeled LacO array on the chromosome. After DSB induction, Pol IV localized to the DSB site in ∼70% of SOS-induced cells. RecA also formed foci at the DSB sites, and Pol IV localized to the RecA foci. These results suggest that Pol IV interacts with RecA in vivo and is recruited to sites of DSBs to aid in the restoration of DNA replication. DNA polymerase IV (Pol IV/DinB) is an error-prone DNA polymerase capable of bypassing DNA lesions and aiding in the restart of stalled replication forks. In this work, we demonstrate in vivo localization of fluorescently tagged Pol IV to the nucleoid after DNA damage and to DNA double-strand breaks. We show colocalization of Pol IV with two proteins: Rep DNA helicase, which participates in replication, and RecA, which catalyzes recombinational repair of stalled replication forks. Time course experiments suggest that Pol IV recruits Rep and that RecA recruits Pol IV. These findings provide in vivo evidence

  1. Structure and mechanism of human DNA polymerase [eta

    Energy Technology Data Exchange (ETDEWEB)

    Biertümpfel, Christian; Zhao, Ye; Kondo, Yuji; Ramón-Maiques, Santiago; Gregory, Mark; Lee, Jae Young; Masutani, Chikahide; Lehmann, Alan R.; Hanaoka, Fumio; Yang, Wei (Sussex); (NIH); (Gakushuin); (Osaka)

    2010-11-03

    The variant form of the human syndrome xeroderma pigmentosum (XPV) is caused by a deficiency in DNA polymerase {eta} (Pol{eta}), a DNA polymerase that enables replication through ultraviolet-induced pyrimidine dimers. Here we report high-resolution crystal structures of human Pol{eta} at four consecutive steps during DNA synthesis through cis-syn cyclobutane thymine dimers. Pol{eta} acts like a 'molecular splint' to stabilize damaged DNA in a normal B-form conformation. An enlarged active site accommodates the thymine dimer with excellent stereochemistry for two-metal ion catalysis. Two residues conserved among Pol{eta} orthologues form specific hydrogen bonds with the lesion and the incoming nucleotide to assist translesion synthesis. On the basis of the structures, eight Pol{eta} missense mutations causing XPV can be rationalized as undermining the molecular splint or perturbing the active-site alignment. The structures also provide an insight into the role of Pol{eta} in replicating through D loop and DNA fragile sites.

  2. Conformational Dynamics of Thermus aquaticus DNA Polymerase I during Catalysis

    Science.gov (United States)

    Suo, Zucai

    2014-01-01

    Despite the fact that DNA polymerases have been investigated for many years and are commonly used as tools in a number of molecular biology assays, many details of the kinetic mechanism they use to catalyze DNA synthesis remain unclear. Structural and kinetic studies have characterized a rapid, pre-catalytic open-to-close conformational change of the Finger domain during nucleotide binding for many DNA polymerases including Thermus aquaticus DNA polymerase I (Taq Pol), a thermostable enzyme commonly used for DNA amplification in PCR. However, little has been done to characterize the motions of other structural domains of Taq Pol or any other DNA polymerase during catalysis. Here, we used stopped-flow Förster resonance energy transfer (FRET) to investigate the conformational dynamics of all five structural domains of the full-length Taq Pol relative to the DNA substrate during nucleotide binding and incorporation. Our study provides evidence for a rapid conformational change step induced by dNTP binding and a subsequent global conformational transition involving all domains of Taq Pol during catalysis. Additionally, our study shows that the rate of the global transition was greatly increased with the truncated form of Taq Pol lacking the N-terminal domain. Finally, we utilized a mutant of Taq Pol containing a de novo disulfide bond to demonstrate that limiting protein conformational flexibility greatly reduced the polymerization activity of Taq Pol. PMID:24931550

  3. Sulfolobus Replication Factor C stimulates the activity of DNA Polymerase B1

    DEFF Research Database (Denmark)

    Xing, Xuanxuan; Zhang, Likui; Guo, Li

    2014-01-01

    the hyperthermophilic archaea of the genus Sulfolobus physically interacts with DNA polymerase B1 (PolB1) and enhances both the polymerase and 3'-5' exonuclease activities of PolB1 in an ATP-independent manner. Stimulation of the PolB1 activity by RFC is independent of the ability of RFC to bind DNA but is consistent...... with the ability of RFC to facilitate DNA binding by PolB1 through protein-protein interaction. These results suggest that Sulfolobus RFC may play a role in recruiting DNA polymerase for efficient primer extension, in addition to clamp loading, during DNA replication....

  4. PCR fidelity of pfu DNA polymerase and other thermostable DNA polymerases.

    Science.gov (United States)

    Cline, J; Braman, J C; Hogrefe, H H

    1996-09-15

    The replication fidelities of Pfu, Taq, Vent, Deep Vent and UlTma DNA polymerases were compared using a PCR-based forward mutation assay. Average error rates (mutation frequency/bp/duplication) increased as follows: Pfu (1.3 x 10(-6)) Pfu and UlTma (approximately 5 x 10(-5)). Buffer optimization experiments indicated that Pfu fidelity was highest in the presence of 2-3 mM MgSO4 and 100-300 microM each dNTP and at pH 8.5-9.1. Under these conditions, the error rate of exo- Pfu was approximately 40-fold higher (5 x 10(-5)) than the error rate of Pfu. As the reaction pH was raised from pH 8 to 9, the error rate of Pfu decreased approximately 2-fold, while the error rate of exo- Pfu increased approximately 9-fold. An increase in error rate with pH has also been noted for the exonuclease-deficient DNA polymerases Taq and exo- Klenow, suggesting that the parameters which influence replication error rates may be similar in pol l- and alpha-like polymerases. Finally, the fidelity of 'long PCR' DNA polymerase mixtures was examined. The error rates of a Taq/Pfu DNA polymerase mixture and a Klentaq/Pfu DNA polymerase mixture were found to be less than the error rate of Taq DNA polymerase, but approximately 3-4-fold higher than the error rate of Pfu DNA polymerase.

  5. The yeast Saccharomyces cerevisiae DNA polymerase IV: possible involvement in double strand break DNA repair.

    Science.gov (United States)

    Leem, S H; Ropp, P A; Sugino, A

    1994-08-11

    We identified and purified a new DNA polymerase (DNA polymerase IV), which is similar to mammalian DNA polymerase beta, from Saccharomyces cerevisiae and suggested that it is encoded by YCR14C (POLX) on chromosome III. Here, we provided a direct evidence that the purified DNA polymerase IV is indeed encoded by POLX. Strains harboring a pol4 deletion mutation exhibit neither mitotic growth defect nor a meiosis defect, suggesting that DNA polymerase IV participates in nonessential functions in DNA metabolism. The deletion strains did not exhibit UV-sensitivity. However, they did show weak sensitivity to MMS-treatment and exhibited a hyper-recombination phenotype when intragenic recombination was measured during meiosis. Furthermore, MAT alpha pol4 delta segregants had a higher frequency of illegitimate mating with a MAT alpha tester strain than that of wild-type cells. These results suggest that DNA polymerase IV participates in a double-strand break repair pathway. A 3.2kb of the POL4 transcript was weakly expressed in mitotically growing cells. During meiosis, a 2.2 kb POL4 transcript was greatly induced, while the 3.2 kb transcript stayed at constant levels. This induction was delayed in a swi4 delta strain during meiosis, while no effect was observed in a swi6 delta strain.

  6. Involvement of the yeast DNA polymerase delta in DNA repair in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Giot, L. [State University of New York at Stony Brook, Stony Brook, NY. (United States); Chanet, R.; Simon, M.; Facca, C.; Faye, G.

    1997-08-15

    The POL3 encoded catalytic subunit of DNA polymerase delta possesses a highly conserved C-terminal cysteine-rich domain in Saccharomyces cerevisiae. Mutations in some of its cysteine codons display a lethal phenotype, which demonstrates an essential function of this domain. The thermosensitive mutant pol3-13, in which a serine replaces a cysteine of this domain, exhibits a range of defects in DNA repair, such as hypersensitivity to different DNA-damaging agents and deficiency for induced mutagenesis and for recombination. These phenotypes are observed at 24 degrees, a temperature at which DNA replication is almost normal; this differentiates the functions of POL3 in DNA repair and DNA replication. Since spontaneous mutagenesis and spontaneous recombination are efficient in pol3-13, we propose that POL3 plays an important role in DNA repair after irradiation, particularly in the error-prone and recombinational pathways. Extragenic suppressors of pol3-13 are allelic to sdp5-1, previously identified as an extragenic suppressor of pol3-11. SDP5, which is identical to HYS2, encodes a protein homologous to the p50 subunit of bovine and human DNA polymerase delta. SDP5 is most probably the p55 subunit of Pol delta of S. cerevisiae and seems to be associated with the catalytic subunit for both DNA replication and DNA repair. (author)

  7. The role of DNA polymerase {iota} in UV mutational spectra

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jun-Hyuk [Division of Biology, Beckman Research Institute, City of Hope, Duarte, CA 91010 (United States); Besaratinia, Ahmad [Division of Biology, Beckman Research Institute, City of Hope, Duarte, CA 91010 (United States); Lee, Dong-Hyun [Division of Biology, Beckman Research Institute, City of Hope, Duarte, CA 91010 (United States); Lee, Chong-Soon [Department of Biochemistry, College of Natural Sciences, Yeungnam University, Gyongsan 712-749 (Korea, Republic of); Pfeifer, Gerd P. [Division of Biology, Beckman Research Institute, City of Hope, Duarte, CA 91010 (United States)]. E-mail: gpfeifer@coh.org

    2006-07-25

    UVB (280-320 nm) and UVC (200-280 nm) irradiation generate predominantly cyclobutane pyrimidine dimers (CPDs) and (6-4) photoproducts in DNA. CPDs are thought to be responsible for most of the UV-induced mutations. Thymine-thymine CPDs, and probably also CPDs containing cytosine, are replicated in vivo in a largely accurate manner by a DNA polymerase {eta} (Pol {eta}) dependent process. Pol {eta} is a DNA damage-tolerant and error-prone DNA polymerase encoded by the POLH (XPV) gene in humans. Another member of the Y family of error-prone DNA polymerases is POLI encoding DNA polymerase iota (Pol {iota}). In order to clarify the specific role of Pol {iota} in UV mutagenesis, we have used an siRNA knockdown approach in combination with a supF shuttle vector which replicates in mammalian cells, similar as we have previously done for Pol {eta}. Synthetic RNA duplexes were used to efficiently inhibit Pol {iota} expression in 293T cells. The supF shuttle vector was irradiated with 254 nm UVC and replicated in 293T cells in presence of anti-Pol {iota} siRNA. Surprisingly, there was a consistent reduction of recovered plasmid from cells with Pol {iota} knockdown and this was independent of UV irradiation of the plasmid. The supF mutant frequency was unchanged in the siRNA knockdown cells relative to control cells confirming that Pol {iota} does not play an important role in UV mutagenesis. UV-induced supF mutants were sequenced from siRNA-treated cells and controls. Neither the type of mutations nor their distribution along the supF gene were significantly different between controls and siRNA knockdown cells and were predominantly C to T and CC to TT transitions at dipyrimidine sites. These results show that Pol {iota} has no significant role in UV lesion bypass and mutagenesis in vivo and provides some initial data suggesting that this polymerase may be involved in replication of extrachromosomal DNA.

  8. PCR performance of a thermostable heterodimeric archaeal DNA polymerase

    Science.gov (United States)

    Killelea, Tom; Ralec, Céline; Bossé, Audrey; Henneke, Ghislaine

    2014-01-01

    DNA polymerases are versatile tools used in numerous important molecular biological core technologies like the ubiquitous polymerase chain reaction (PCR), cDNA cloning, genome sequencing, and nucleic acid based diagnostics. Taking into account the multiple DNA amplification techniques in use, different DNA polymerases must be optimized for each type of application. One of the current tendencies is to reengineer or to discover new DNA polymerases with increased performance and broadened substrate spectra. At present, there is a great demand for such enzymes in applications, e.g., forensics or paleogenomics. Current major limitations hinge on the inability of conventional PCR enzymes, such as Taq, to amplify degraded or low amounts of template DNA. Besides, a wide range of PCR inhibitors can also impede reactions of nucleic acid amplification. Here we looked at the PCR performances of the proof-reading D-type DNA polymerase from P. abyssi, Pab-polD. Fragments, 3 kilobases in length, were specifically PCR-amplified in its optimized reaction buffer. Pab-polD showed not only a greater resistance to high denaturation temperatures than Taq during cycling, but also a superior tolerance to the presence of potential inhibitors. Proficient proof-reading Pab-polD enzyme could also extend a primer containing up to two mismatches at the 3' primer termini. Overall, we found valuable biochemical properties in Pab-polD compared to the conventional Taq, which makes the enzyme ideally suited for cutting-edge PCR-applications. PMID:24847315

  9. PCR performance of a thermostable heterodimeric archaeal DNA polymerase

    Directory of Open Access Journals (Sweden)

    Tom eKillelea

    2014-05-01

    Full Text Available DNA polymerases are versatile tools used in numerous important molecular biological core technologies like the ubiquitous polymerase chain reaction (PCR, cDNA cloning, genome sequencing and nucleic acid based diagnostics. Taking into account the multiple DNA amplification techniques in use, different DNA polymerases must be optimized for each type of application. One of the current tendencies is to reengineer or to discover new DNA polymerases with increased performance and broadened substrate spectra. At present, there is a great demand for such enzymes in applications, e.g., forensics or paleogenomics. Current major limitations hinge on the inability of conventional PCR enzymes, such as Taq, to amplify degraded or low amounts of template DNA. Besides, a wide range of PCR inhibitors can also impede reactions of nucleic acid amplification. Here we looked at the PCR performances of the proof-reading D-type DNA polymerase from P. abyssi, Pab-polD. Fragments, 3 kilobases in length, were specifically PCR-amplified in its optimized reaction buffer. Pab-polD showed not only a greater resistance to high denaturation temperatures than Taq during cycling, but also a superior tolerance to the presence of potential inhibitors. Proficient proof-reading Pab-polD enzyme could also extend a primer containing up to two mismatches at the 3’ primer termini. Overall, we found valuable biochemical properties in Pab-polD compared to the conventional Taq, which makes the enzyme ideally suited for cutting-edge PCR-applications.

  10. DNA polymerases beta and lambda mediate overlapping and independent roles in base excision repair in mouse embryonic fibroblasts.

    Directory of Open Access Journals (Sweden)

    Elena K Braithwaite

    2010-08-01

    Full Text Available Base excision repair (BER is a DNA repair pathway designed to correct small base lesions in genomic DNA. While DNA polymerase beta (pol beta is known to be the main polymerase in the BER pathway, various studies have implicated other DNA polymerases in back-up roles. One such polymerase, DNA polymerase lambda (pol lambda, was shown to be important in BER of oxidative DNA damage. To further explore roles of the X-family DNA polymerases lambda and beta in BER, we prepared a mouse embryonic fibroblast cell line with deletions in the genes for both pol beta and pol lambda. Neutral red viability assays demonstrated that pol lambda and pol beta double null cells were hypersensitive to alkylating and oxidizing DNA damaging agents. In vitro BER assays revealed a modest contribution of pol lambda to single-nucleotide BER of base lesions. Additionally, using co-immunoprecipitation experiments with purified enzymes and whole cell extracts, we found that both pol lambda and pol beta interact with the upstream DNA glycosylases for repair of alkylated and oxidized DNA bases. Such interactions could be important in coordinating roles of these polymerases during BER.

  11. Kinetic Analysis of the Bypass of a Bulky DNA Lesion Catalyzed by Human Y-family DNA Polymerases

    Science.gov (United States)

    Sherrer, Shanen M.; Sanman, Laura E.; Xia, Cynthia X.; Bolin, Eric R.; Malik, Chanchal K.; Efthimiopoulos, Georgia; Basu, Ashis K.; Suo, Zucai

    2012-01-01

    1-Nitropyrene (1-NP), a mutagen and potential carcinogen, is the most abundant nitro polyaromatic hydrocarbon in diesel exhaust, which reacts with DNA to form predominantly N-(deoxyguanosin-8-yl)-1-aminopyrene (dGAP). If not repaired, this DNA lesion is presumably bypassed in vivo by any of human Y-family DNA polymerases kappa (hPolκ), iota (hPolτ), eta (hPolη), and Rev1 (hRev1). Our running start assays demonstrated that each of these enzymes was indeed capable of traversing a site-specifically placed dGAP on a synthetic DNA template but hRev1 was stopped after lesion bypass. The time required to bypass 50% of the dGAP sites (t50bypass ) encountered by hPolη, hPolκ and hPolτ was determined to be 2.5 s, 4.1 s, and 106.5 s, respectively. The efficiency order of catalyzing translesion synthesis of dGAP (hPolη > hPolκ > hPolτ >> hRev1) is the same as the order for these human Y-family enzymes to elongate undamaged DNA. Although hPolη bypassed dGAP efficiently, replication by both hPolκ and hPolτ was strongly stalled at the lesion site and at a site immediately downstream from dGAP. By employing pre-steady state kinetic methods, a kinetic basis was established for polymerase pausing at these DNA template sites. Besides efficiency of bypass, the fidelity of those low-fidelity polymerases at these pause sites was also significantly decreased. Thus, if the translesion DNA synthesis of dGAP in vivo is catalyzed by a human Y-family DNA polymerase, e.g. hPolη, the process is certainly mutagenic. PMID:22324639

  12. Transient expression and activity of human DNA polymerase iota in loach embryos.

    Science.gov (United States)

    Makarova, Irina V; Kazakov, Andrey A; Makarova, Alena V; Khaidarova, Nella V; Kozikova, Larisa V; Nenasheva, Valentina V; Gening, Leonid V; Tarantul, Vyacheslav Z; Andreeva, Ludmila E

    2012-02-01

    Human DNA polymerase iota (Pol ι) is a Y-family DNA polymerase with unusual biochemical properties and not fully understood functions. Pol ι preferentially incorporates dGTP opposite template thymine. This property can be used to monitor Pol ι activity in the presence of other DNA polymerases, e.g. in cell extracts of tissues and tumors. We have now confirmed the specificity and sensitivity of the method of Pol ι activity detection in cell extracts using an animal model of loach Misgurnus fossilis embryos transiently expressing human Pol ι. The overexpression of Pol ι was shown to be accompanied by an increase in abnormalities in development and the frequency of pycnotic nuclei in fish embryos. Further analysis of fish embryos with constitutive or regulated Pol ι expression may provide insights into Pol ι functions in vertebrate animals.

  13. Primer-Independent DNA Synthesis by a Family B DNA Polymerase from Self-Replicating Mobile Genetic Elements

    Directory of Open Access Journals (Sweden)

    Modesto Redrejo-Rodríguez

    2017-11-01

    Full Text Available Family B DNA polymerases (PolBs play a central role during replication of viral and cellular chromosomes. Here, we report the discovery of a third major group of PolBs, which we denote primer-independent PolB (piPolB, that might be a link between the previously known protein-primed and RNA/DNA-primed PolBs. PiPolBs are encoded by highly diverse mobile genetic elements, pipolins, integrated in the genomes of diverse bacteria and also present as circular plasmids in mitochondria. Biochemical characterization showed that piPolB displays efficient DNA polymerization activity that can use undamaged and damaged templates and is endowed with proofreading and strand displacement capacities. Remarkably, the protein is also capable of template-dependent de novo DNA synthesis, i.e., DNA-priming activity, thereby breaking the long-standing dogma that replicative DNA polymerases require a pre-existing primer for DNA synthesis. We suggest that piPolBs are involved in self-replication of pipolins and may also contribute to bacterial DNA damage tolerance.

  14. Sequence and transcription analysis of the human cytomegalovirus DNA polymerase gene

    International Nuclear Information System (INIS)

    Kouzarides, T.; Bankier, A.T.; Satchwell, S.C.; Weston, K.; Tomlinson, P.; Barrell, B.G.

    1987-01-01

    DNA sequence analysis has revealed that the gene coding for the human cytomegalovirus (HCMV) DNA polymerase is present within the long unique region of the virus genome. Identification is based on extensive amino acid homology between the predicted HCMV open reading frame HFLF2 and the DNA polymerase of herpes simplex virus type 1. The authors present here a 5280 base-pair DNA sequence containing the HCMV pol gene, along with the analysis of transcripts encoded within this region. Since HCMV pol also shows homology to the predicted Epstein-Barr virus pol, they were able to analyze the extent of homology between the DNA polymerases of three distantly related herpes viruses, HCMV, Epstein-Barr virus, and herpes simplex virus. The comparison shows that these DNA polymerases exhibit considerable amino acid homology and highlights a number of highly conserved regions; two such regions show homology to sequences within the adenovirus type 2 DNA polymerase. The HCMV pol gene is flanked by open reading frames with homology to those of other herpes viruses; upstream, there is a reading frame homologous to the glycoprotein B gene of herpes simplex virus type I and Epstein-Barr virus, and downstream there is a reading frame homologous to BFLF2 of Epstein-Barr virus

  15. Nuclear DNA polymerase beta from Leishmania infantum. Cloning, molecular analysis and developmental regulation

    Science.gov (United States)

    Taladriz, Soraya; Hanke, Tobias; Ramiro, María J.; García-Díaz, Miguel; Lacoba, Mario García de; Blanco, Luis; Larraga, Vicente

    2001-01-01

    We have identified a novel polymerase beta (Pol β)-like enzyme from Leishmania infantum, a parasite protozoon causing disease in humans. This protein, named Li Pol β, shows a nuclear localization that contrasts with the mitochondrial localization of Pol β from Crithidia fasciculata, a closely related parasite, the only polymerase β described so far in Trypanosomatidae. Li Pol β, that belongs to the DNA polymerase X family, displays an evolutionarily conserved Pol β-type DNA polymerase core, in which most of the key residues involved in DNA binding, nucleotide binding, dRPase and polymerization catalysis are conserved. In agreement with this, Li Pol β, overproduced in Escherichia coli, displayed intrinsic DNA polymerase activity. Cell synchronization experiments showed a correlation between both Li Pol β mRNA and protein levels along the parasite cell cycle. Analysis of these parameters at the different growth phases of the parasite, from the proliferative (non-infective) logarithmic phase to the non-dividing (highly infectious) stationary phase, showed high levels of Li Pol β at the infective phase of the parasite. The data suggest a role of Li Pol β in base excision repair in L.infantum, a parasite usually affected by oxygen stress environments into the macrophage host cells. PMID:11557814

  16. Quantitative Analysis of the Mutagenic Potential of 1-Aminopyrene-DNA Adduct Bypass Catalyzed by Y-Family DNA Polymerases

    Science.gov (United States)

    Sherrer, Shanen M.; Taggart, David J.; Pack, Lindsey R.; Malik, Chanchal K.; Basu, Ashis K.; Suo, Zucai

    2012-01-01

    N- (deoxyguanosin-8-yl)-1-aminopyrene (dGAP) is the predominant nitro polyaromatic hydrocarbon product generated from the air pollutant 1-nitropyrene reacting with DNA. Previous studies have shown that dGAP induces genetic mutations in bacterial and mammalian cells. One potential source of these mutations is the error-prone bypass of dGAP lesions catalyzed by the low-fidelity Y-family DNA polymerases. To provide a comparative analysis of the mutagenic potential of the translesion DNA synthesis (TLS) of dGAP, we employed short oligonucleotide sequencing assays (SOSAs) with the model Y-family DNA polymerase from Sulfolobus solfataricus, DNA Polymerase IV (Dpo4), and the human Y-family DNA polymerases eta (hPolη), kappa (hPolκ), and iota (hPolι). Relative to undamaged DNA, all four enzymes generated far more mutations (base deletions, insertions, and substitutions) with a DNA template containing a site-specifically placed dGAP. Opposite dGAP and at an immediate downstream template position, the most frequent mutations made by the three human enzymes were base deletions and the most frequent base substitutions were dAs for all enzymes. Based on the SOSA data, Dpo4 was the least error-prone Y-family DNA polymerase among the four enzymes during the TLS of dGAP. Among the three human Y-family enzymes, hPolκ made the fewest mutations at all template positions except opposite the lesion site. hPolκ was significantly less error-prone than hPolι and hPolη during the extension of dGAP bypass products. Interestingly, the most frequent mutations created by hPolι at all template positions were base deletions. Although hRev1, the fourth human Y-family enzyme, could not extend dGAP bypass products in our standing start assays, it preferentially incorporated dCTP opposite the bulky lesion. Collectively, these mutagenic profiles suggest that hPolkk and hRev1 are the most suitable human Y-family DNA polymerases to perform TLS of dGAP in humans. PMID:22917544

  17. The yeast Saccharomyces cerevisiae DNA polymerase IV: possible involvement in double strand break DNA repair.

    OpenAIRE

    Leem, S H; Ropp, P A; Sugino, A

    1994-01-01

    We identified and purified a new DNA polymerase (DNA polymerase IV), which is similar to mammalian DNA polymerase beta, from Saccharomyces cerevisiae and suggested that it is encoded by YCR14C (POLX) on chromosome III. Here, we provided a direct evidence that the purified DNA polymerase IV is indeed encoded by POLX. Strains harboring a pol4 deletion mutation exhibit neither mitotic growth defect nor a meiosis defect, suggesting that DNA polymerase IV participates in nonessential functions in ...

  18. How a low-fidelity DNA polymerase chooses non-Watson-Crick from Watson-Crick incorporation.

    Science.gov (United States)

    Wu, Wen-Jin; Su, Mei-I; Wu, Jian-Li; Kumar, Sandeep; Lim, Liang-Hin; Wang, Chun-Wei Eric; Nelissen, Frank H T; Chen, Ming-Chuan Chad; Doreleijers, Jurgen F; Wijmenga, Sybren S; Tsai, Ming-Daw

    2014-04-02

    A dogma for DNA polymerase catalysis is that the enzyme binds DNA first, followed by MgdNTP. This mechanism contributes to the selection of correct dNTP by Watson-Crick base pairing, but it cannot explain how low-fidelity DNA polymerases overcome Watson-Crick base pairing to catalyze non-Watson-Crick dNTP incorporation. DNA polymerase X from the deadly African swine fever virus (Pol X) is a half-sized repair polymerase that catalyzes efficient dG:dGTP incorporation in addition to correct repair. Here we report the use of solution structures of Pol X in the free, binary (Pol X:MgdGTP), and ternary (Pol X:DNA:MgdGTP with dG:dGTP non-Watson-Crick pairing) forms, along with functional analyses, to show that Pol X uses multiple unprecedented strategies to achieve the mutagenic dG:dGTP incorporation. Unlike high fidelity polymerases, Pol X can prebind purine MgdNTP tightly and undergo a specific conformational change in the absence of DNA. The prebound MgdGTP assumes an unusual syn conformation stabilized by partial ring stacking with His115. Upon binding of a gapped DNA, also with a unique mechanism involving primarily helix αE, the prebound syn-dGTP forms a Hoogsteen base pair with the template anti-dG. Interestingly, while Pol X prebinds MgdCTP weakly, the correct dG:dCTP ternary complex is readily formed in the presence of DNA. H115A mutation disrupted MgdGTP binding and dG:dGTP ternary complex formation but not dG:dCTP ternary complex formation. The results demonstrate the first solution structural view of DNA polymerase catalysis, a unique DNA binding mode, and a novel mechanism for non-Watson-Crick incorporation by a low-fidelity DNA polymerase.

  19. Evidence that DNA polymerase δ contributes to initiating leading strand DNA replication in Saccharomyces cerevisiae.

    Science.gov (United States)

    Garbacz, Marta A; Lujan, Scott A; Burkholder, Adam B; Cox, Phillip B; Wu, Qiuqin; Zhou, Zhi-Xiong; Haber, James E; Kunkel, Thomas A

    2018-02-27

    To investigate nuclear DNA replication enzymology in vivo, we have studied Saccharomyces cerevisiae strains containing a pol2-16 mutation that inactivates the catalytic activities of DNA polymerase ε (Pol ε). Although pol2-16 mutants survive, they present very tiny spore colonies, increased doubling time, larger than normal cells, aberrant nuclei, and rapid acquisition of suppressor mutations. These phenotypes reveal a severe growth defect that is distinct from that of strains that lack only Pol ε proofreading (pol2-4), consistent with the idea that Pol ε is the major leading-strand polymerase used for unstressed DNA replication. Ribonucleotides are incorporated into the pol2-16 genome in patterns consistent with leading-strand replication by Pol δ when Pol ε is absent. More importantly, ribonucleotide distributions at replication origins suggest that in strains encoding all three replicases, Pol δ contributes to initiation of leading-strand replication. We describe two possible models.

  20. Nucleotide-mimetic synthetic ligands for DNA-recognizing enzymes One-step purification of Pfu DNA polymerase.

    Science.gov (United States)

    Melissis, S; Labrou, N E; Clonis, Y D

    2006-07-28

    The commercial availability of DNA polymerases has revolutionized molecular biotechnology and certain sectors of the bio-industry. Therefore, the development of affinity adsorbents for purification of DNA polymerases is of academic interest and practical importance. In the present study we describe the design, synthesis and evaluation of a combinatorial library of novel affinity ligands for the purification of DNA polymerases (Pols). Pyrococcus furiosus DNA polymerase (Pfu Pol) was employed as a proof-of-principle example. Affinity ligand design was based on mimicking the natural interactions between deoxynucleoside-triphosphates (dNTPs) and the B-motif, a conserved structural moiety found in Pol-I and Pol-II family of enzymes. Solid-phase 'structure-guided' combinatorial chemistry was used to construct a library of 26 variants of the B-motif-binding 'lead' ligand X-Trz-Y (X is a purine derivative and Y is an aliphatic/aromatic sulphonate or phosphonate derivative) using 1,3,5-triazine (Trz) as the scaffold for assembly. The 'lead' ligand showed complementarity against a Lys and a Tyr residue of the polymerase B-motif. The ligand library was screened for its ability to bind and purify Pfu Pol from Escherichia coli extract. One immobilized ligand (oABSAd), bearing 9-aminoethyladenine (AEAd) and sulfanilic acid (oABS) linked on the triazine scaffold, displayed the highest purifying ability and binding capacity (0,55 mg Pfu Pol/g wet gel). Adsorption equilibrium studies with this affinity ligand and Pfu Pol determined a dissociation constant (K(D)) of 83 nM for the respective complex. The oABSAd affinity adsorbent was exploited in the development of a facile Pfu Pol purification protocol, affording homogeneous enzyme (>99% purity) in a single chromatography step. Quality control tests showed that Pfu Pol purified on the B-motif-complementing ligand is free of nucleic acids and contaminating nuclease activities, therefore, suitable for experimental use.

  1. Archaeal DNA Polymerase-B as a DNA Template Guardian: Links between Polymerases and Base/Alternative Excision Repair Enzymes in Handling the Deaminated Bases Uracil and Hypoxanthine

    Directory of Open Access Journals (Sweden)

    Javier Abellón-Ruiz

    2016-01-01

    Full Text Available In Archaea repair of uracil and hypoxanthine, which arise by deamination of cytosine and adenine, respectively, is initiated by three enzymes: Uracil-DNA-glycosylase (UDG, which recognises uracil; Endonuclease V (EndoV, which recognises hypoxanthine; and Endonuclease Q (EndoQ, (which recognises both uracil and hypoxanthine. Two archaeal DNA polymerases, Pol-B and Pol-D, are inhibited by deaminated bases in template strands, a feature unique to this domain. Thus the three repair enzymes and the two polymerases show overlapping specificity for uracil and hypoxanthine. Here it is demonstrated that binding of Pol-D to primer-templates containing deaminated bases inhibits the activity of UDG, EndoV, and EndoQ. Similarly Pol-B almost completely turns off EndoQ, extending earlier work that demonstrated that Pol-B reduces catalysis by UDG and EndoV. Pol-B was observed to be a more potent inhibitor of the enzymes compared to Pol-D. Although Pol-D is directly inhibited by template strand uracil, the presence of Pol-B further suppresses any residual activity of Pol-D, to near-zero levels. The results are compatible with Pol-D acting as the replicative polymerase and Pol-B functioning primarily as a guardian preventing deaminated base-induced DNA mutations.

  2. The SOS and RpoS Regulons Contribute to Bacterial Cell Robustness to Genotoxic Stress by Synergistically Regulating DNA Polymerase Pol II.

    Science.gov (United States)

    Dapa, Tanja; Fleurier, Sébastien; Bredeche, Marie-Florence; Matic, Ivan

    2017-07-01

    Mitomycin C (MMC) is a genotoxic agent that induces DNA cross-links, DNA alkylation, and the production of reactive oxygen species (ROS). MMC induces the SOS response and RpoS regulons in Escherichia coli SOS-encoded functions are required for DNA repair, whereas the RpoS regulon is typically induced by metabolic stresses that slow growth. Thus, induction of the RpoS regulon by MMC may be coincidental, because DNA damage slows growth; alternatively, the RpoS regulon may be an adaptive response contributing to cell survival. In this study, we show that the RpoS regulon is primarily induced by MMC-induced ROS production. We also show that RpoS regulon induction is required for the survival of MMC-treated growing cells. The major contributor to RpoS-dependent resistance to MMC treatment is DNA polymerase Pol II, which is encoded by the polB gene belonging to the SOS regulon. The observation that polB gene expression is controlled by the two major stress response regulons that are required to maximize survival and fitness further emphasizes the key role of this DNA polymerase as an important factor in genome stability. Copyright © 2017 by the Genetics Society of America.

  3. Shared active site architecture between archaeal PolD and multi-subunit RNA polymerases revealed by X-ray crystallography

    OpenAIRE

    Sauguet , Ludovic; Raia , Pierre; Henneke , Ghislaine; Delarue , Marc

    2016-01-01

    International audience; Archaeal replicative DNA polymerase D (PolD) constitute an atypical class of DNA polymerases made of a proofreading exonuclease subunit (DP1) and a larger polymerase catalytic subunit (DP2), both with unknown structures. We have determined the crystal structures of Pyrococcus abyssi DP1 and DP2 at 2.5 and 2.2 Å resolution, respectively, revealing a catalytic core strikingly different from all other known DNA polymerases (DNAPs). Rather, the PolD DP2 catalytic core has ...

  4. DnaB gene product-independence of DNA polymerase III-directed repair synthesis in Escherichia coli K-12

    International Nuclear Information System (INIS)

    Billen, D.; Hellermann, G.R.

    1977-01-01

    An investigation has been carried out into the role of dnaB gene product in X-ray-induced repair synthesis carried out by DNA polymerase III in toluene-treated Escherichia coli K-12. A polAl polBlOO dnaB mutant deficient in both DNA polymerase I and II activities was used, and it was shown that the level of X-ray-induced, ATP-dependent, non-conservative DNA synthesis was, unlike semi-conservative DNA synthesis, unaffected by a temperature shift from 30 0 to 42 0 C. The dnaB gene product was not therefore necessary for DNA polymerase III-directed repair synthesis, which occurred in the absence of replicative synthesis. (U.K.)

  5. Pre-Steady-State Kinetic Analysis of Truncated and Full-Length Saccharomyces cerevisiae DNA Polymerase Eta

    Science.gov (United States)

    Brown, Jessica A.; Zhang, Likui; Sherrer, Shanen M.; Taylor, John-Stephen; Burgers, Peter M. J.; Suo, Zucai

    2010-01-01

    Understanding polymerase fidelity is an important objective towards ascertaining the overall stability of an organism's genome. Saccharomyces cerevisiae DNA polymerase η (yPolη), a Y-family DNA polymerase, is known to efficiently bypass DNA lesions (e.g., pyrimidine dimers) in vivo. Using pre-steady-state kinetic methods, we examined both full-length and a truncated version of yPolη which contains only the polymerase domain. In the absence of yPolη's C-terminal residues 514–632, the DNA binding affinity was weakened by 2-fold and the base substitution fidelity dropped by 3-fold. Thus, the C-terminus of yPolη may interact with DNA and slightly alter the conformation of the polymerase domain during catalysis. In general, yPolη discriminated between a correct and incorrect nucleotide more during the incorporation step (50-fold on average) than the ground-state binding step (18-fold on average). Blunt-end additions of dATP or pyrene nucleotide 5′-triphosphate revealed the importance of base stacking during the binding of incorrect incoming nucleotides. PMID:20798853

  6. Pre-Steady-State Kinetic Analysis of Truncated and Full-Length Saccharomyces cerevisiae DNA Polymerase Eta

    Directory of Open Access Journals (Sweden)

    Jessica A. Brown

    2010-01-01

    Full Text Available Understanding polymerase fidelity is an important objective towards ascertaining the overall stability of an organism's genome. Saccharomyces cerevisiae DNA polymerase η (yPolη, a Y-family DNA polymerase, is known to efficiently bypass DNA lesions (e.g., pyrimidine dimers in vivo. Using pre-steady-state kinetic methods, we examined both full-length and a truncated version of yPolη which contains only the polymerase domain. In the absence of yPolη's C-terminal residues 514–632, the DNA binding affinity was weakened by 2-fold and the base substitution fidelity dropped by 3-fold. Thus, the C-terminus of yPolη may interact with DNA and slightly alter the conformation of the polymerase domain during catalysis. In general, yPolη discriminated between a correct and incorrect nucleotide more during the incorporation step (50-fold on average than the ground-state binding step (18-fold on average. Blunt-end additions of dATP or pyrene nucleotide 5′-triphosphate revealed the importance of base stacking during the binding of incorrect incoming nucleotides.

  7. Production of DNA polymerase by recombinant pET-17b/Pfu-Pol ...

    African Journals Online (AJOL)

    Although this enzyme has been produced worldwide, there is no reported cloning or production of polymerases in Egypt. In the current work, plasmid coding Pfu polymerase enzyme (pET-17b/Pfu-Pol) was transformed into E. coli Top10. The plasmid coding Pfu- polymerase was confirmed by restriction analysis using HindIII ...

  8. Two Family B DNA Polymerases From Aeropyrum pernix, Based on Revised Translational Frames

    Directory of Open Access Journals (Sweden)

    Katsuya Daimon

    2018-04-01

    Full Text Available Living organisms are divided into three domains, Bacteria, Eukarya, and Archaea. Comparative studies in the three domains have provided useful information to understand the evolution of the DNA replication machinery. DNA polymerase is the central enzyme of DNA replication. The presence of multiple family B DNA polymerases is unique in Crenarchaeota, as compared with other archaeal phyla, which have a single enzyme each for family B (PolB and family D (PolD. We analyzed PolB1 and PolB3 in the hyperthermophilic crenarchaeon, Aeropyrum pernix, and found that they are larger proteins than those predicted from the coding regions in our previous study and from public database annotations. The recombinant larger PolBs exhibited the same DNA polymerase activities as previously reported. However, the larger PolB3 showed remarkably higher thermostability, which made this enzyme applicable to PCR. In addition, the high tolerance to salt and heparin suggests that PolB3 will be useful for amplification from the samples with contaminants, and therefore it has a great potential for diagnostic use in the medical and environmental field.

  9. Prediction of Active Site and Distal Residues in E. coli DNA Polymerase III alpha Polymerase Activity.

    Science.gov (United States)

    Parasuram, Ramya; Coulther, Timothy A; Hollander, Judith M; Keston-Smith, Elise; Ondrechen, Mary Jo; Beuning, Penny J

    2018-02-20

    The process of DNA replication is carried out with high efficiency and accuracy by DNA polymerases. The replicative polymerase in E. coli is DNA Pol III, which is a complex of 10 different subunits that coordinates simultaneous replication on the leading and lagging strands. The 1160-residue Pol III alpha subunit is responsible for the polymerase activity and copies DNA accurately, making one error per 10 5 nucleotide incorporations. The goal of this research is to determine the residues that contribute to the activity of the polymerase subunit. Homology modeling and the computational methods of THEMATICS and POOL were used to predict functionally important amino acid residues through their computed chemical properties. Site-directed mutagenesis and biochemical assays were used to validate these predictions. Primer extension, steady-state single-nucleotide incorporation kinetics, and thermal denaturation assays were performed to understand the contribution of these residues to the function of the polymerase. This work shows that the top 15 residues predicted by POOL, a set that includes the three previously known catalytic aspartate residues, seven remote residues, plus five previously unexplored first-layer residues, are important for function. Six previously unidentified residues, R362, D405, K553, Y686, E688, and H760, are each essential to Pol III activity; three additional residues, Y340, R390, and K758, play important roles in activity.

  10. Engineering of DNA polymerase I from Thermus thermophilus using compartmentalized self-replication.

    Science.gov (United States)

    Aye, Seaim Lwin; Fujiwara, Kei; Ueki, Asuka; Doi, Nobuhide

    2018-05-05

    Although compartmentalized self-replication (CSR) and compartmentalized partnered replication (CPR) are powerful tools for directed evolution of proteins and gene circuits, limitations remain in the emulsion PCR process with the wild-type Taq DNA polymerase used so far, including long run times, low amounts of product, and false negative results due to inhibitors. In this study, we developed a high-efficiency mutant of DNA polymerase I from Thermus thermophilus HB27 (Tth pol) suited for CSR and CPR. We modified the wild-type Tth pol by (i) deletion of the N-terminal 5' to 3' exonuclease domain, (ii) fusion with the DNA-binding protein Sso7d, (iii) introduction of four known effective point mutations from other DNA polymerase mutants, and (iv) codon optimization to reduce the GC content. Consequently, we obtained a mutant that provides higher product yields than the conventional Taq pol without decreased fidelity. Next, we performed four rounds of CSR selection with a randomly mutated library of this modified Tth pol and obtained mutants that provide higher product yields in fewer cycles of emulsion PCR than the parent Tth pol as well as the conventional Taq pol. Copyright © 2018 Elsevier Inc. All rights reserved.

  11. Replication slippage of the thermophilic DNA polymerases B and D from the Euryarchaeota Pyrococcus abyssi

    Directory of Open Access Journals (Sweden)

    Melissa G. eCastillo-Lizardo

    2014-08-01

    Full Text Available Replication slippage or slipped-strand mispairing involves the misalignment of DNA strands during the replication of repeated DNA sequences, and can lead to genetic rearrangements such as microsatellite instability. Here, we show that PolB and PolD replicative DNA polymerases from the archaeal model Pyrococcus abyssi (Pab slip in vitro during replication of a single-stranded DNA template carrying a hairpin structure and short direct repeats. We find that this occurs in both their wild-type (exo+ and exonuclease deficient (exo- forms. The slippage behavior of PabPolB and PabPolD, probably due to limited strand displacement activity, resembles that observed for the high fidelity Pyrococcus furiosus (Pfu DNA polymerase. The presence of PabPCNA inhibited PabPolB and PabPolD slippage. We propose a model whereby PabPCNA stimulates strand displacement activity and polymerase progression through the hairpin, thus permitting the error-free replication of repetitive sequences.

  12. Conformational Dynamics of Thermus aquaticus DNA Polymerase I during Catalysis

    OpenAIRE

    Xu, Cuiling; Maxwell, Brian A.; Suo, Zucai

    2014-01-01

    Despite the fact that DNA polymerases have been investigated for many years and are commonly used as tools in a number of molecular biology assays, many details of the kinetic mechanism they use to catalyze DNA synthesis remain unclear. Structural and kinetic studies have characterized a rapid, pre-catalytic open-to-close conformational change of the Finger domain during nucleotide binding for many DNA polymerases including Thermus aquaticus DNA polymerase I (Taq Pol), a thermostable enzyme c...

  13. Structure of a preternary complex involving a prokaryotic NHEJ DNA polymerase.

    Science.gov (United States)

    Brissett, Nigel C; Martin, Maria J; Pitcher, Robert S; Bianchi, Julie; Juarez, Raquel; Green, Andrew J; Fox, Gavin C; Blanco, Luis; Doherty, Aidan J

    2011-01-21

    In many prokaryotes, a specific DNA primase/polymerase (PolDom) is required for nonhomologous end joining (NHEJ) repair of DNA double-strand breaks (DSBs). Here, we report the crystal structure of a catalytically active conformation of Mycobacterium tuberculosis PolDom, consisting of a polymerase bound to a DNA end with a 3' overhang, two metal ions, and an incoming nucleotide but, significantly, lacking a primer strand. This structure represents a polymerase:DNA complex in a preternary intermediate state. This polymerase complex occurs in solution, stabilizing the enzyme on DNA ends and promoting nucleotide extension of short incoming termini. We also demonstrate that the invariant Arg(220), contained in a conserved loop (loop 2), plays an essential role in catalysis by regulating binding of a second metal ion in the active site. We propose that this NHEJ intermediate facilitates extension reactions involving critically short or noncomplementary DNA ends, thus promoting break repair and minimizing sequence loss during DSB repair. Copyright © 2011 Elsevier Inc. All rights reserved.

  14. Atomistic Molecular Dynamics Simulations of Mitochondrial DNA Polymerase γ

    DEFF Research Database (Denmark)

    Euro, Liliya; Haapanen, Outi; Róg, Tomasz

    2017-01-01

    of replisomal interactions, and functional effects of patient mutations that do not affect direct catalysis have remained elusive. Here we report the first atomistic classical molecular dynamics simulations of the human Pol γ replicative complex. Our simulation data show that DNA binding triggers remarkable......DNA polymerase γ (Pol γ) is a key component of the mitochondrial DNA replisome and an important cause of neurological diseases. Despite the availability of its crystal structures, the molecular mechanism of DNA replication, the switch between polymerase and exonuclease activities, the site...... changes in the enzyme structure, including (1) completion of the DNA-binding channel via a dynamic subdomain, which in the apo form blocks the catalytic site, (2) stabilization of the structure through the distal accessory β-subunit, and (3) formation of a putative transient replisome-binding platform...

  15. Shared active site architecture between archaeal PolD and multi-subunit RNA polymerases revealed by X-ray crystallography.

    Science.gov (United States)

    Sauguet, Ludovic; Raia, Pierre; Henneke, Ghislaine; Delarue, Marc

    2016-08-22

    Archaeal replicative DNA polymerase D (PolD) constitute an atypical class of DNA polymerases made of a proofreading exonuclease subunit (DP1) and a larger polymerase catalytic subunit (DP2), both with unknown structures. We have determined the crystal structures of Pyrococcus abyssi DP1 and DP2 at 2.5 and 2.2 Å resolution, respectively, revealing a catalytic core strikingly different from all other known DNA polymerases (DNAPs). Rather, the PolD DP2 catalytic core has the same 'double-psi β-barrel' architecture seen in the RNA polymerase (RNAP) superfamily, which includes multi-subunit transcriptases of all domains of life, homodimeric RNA-silencing pathway RNAPs and atypical viral RNAPs. This finding bridges together, in non-viral world, DNA transcription and DNA replication within the same protein superfamily. This study documents further the complex evolutionary history of the DNA replication apparatus in different domains of life and proposes a classification of all extant DNAPs.

  16. Exonuclease of human DNA polymerase gamma disengages its strand displacement function.

    Science.gov (United States)

    He, Quan; Shumate, Christie K; White, Mark A; Molineux, Ian J; Yin, Y Whitney

    2013-11-01

    Pol γ, the only DNA polymerase found in human mitochondria, functions in both mtDNA repair and replication. During mtDNA base-excision repair, gaps are created after damaged base excision. Here we show that Pol γ efficiently gap-fills except when the gap is only a single nucleotide. Although wild-type Pol γ has very limited ability for strand displacement DNA synthesis, exo(-) (3'-5' exonuclease-deficient) Pol γ has significantly high activity and rapidly unwinds downstream DNA, synthesizing DNA at a rate comparable to that of the wild-type enzyme on a primer-template. The catalytic subunit Pol γA alone, even when exo(-), is unable to synthesize by strand displacement, making this the only known reaction of Pol γ holoenzyme that has an absolute requirement for the accessory subunit Pol γB. © 2013. Published by Elsevier B.V.

  17. DNA polymerase hybrids derived from the family-B enzymes of Pyrococcus furiosus and Thermococcus kodakarensis: improving performance in the polymerase chain reaction.

    Science.gov (United States)

    Elshawadfy, Ashraf M; Keith, Brian J; Ee Ooi, H'Ng; Kinsman, Thomas; Heslop, Pauline; Connolly, Bernard A

    2014-01-01

    The polymerase chain reaction (PCR) is widely applied across the biosciences, with archaeal Family-B DNA polymerases being preferred, due to their high thermostability and fidelity. The enzyme from Pyrococcus furiosus (Pfu-Pol) is more frequently used than the similar protein from Thermococcus kodakarensis (Tkod-Pol), despite the latter having better PCR performance. Here the two polymerases have been comprehensively compared, confirming that Tkod-Pol: (1) extends primer-templates more rapidly; (2) has higher processivity; (3) demonstrates superior performance in normal and real time PCR. However, Tkod-Pol is less thermostable than Pfu-Pol and both enzymes have equal fidelities. To understand the favorable properties of Tkod-Pol, hybrid proteins have been prepared. Single, double and triple mutations were used to site arginines, present at the "forked-point" (the junction of the exonuclease and polymerase channels) of Tkod-Pol, at the corresponding locations in Pfu-Pol, slightly improving PCR performance. The Pfu-Pol thumb domain, responsible for double-stranded DNA binding, has been entirely replaced with that from Tkod-Pol, again giving better PCR properties. Combining the "forked-point" and thumb swap mutations resulted in a marked increase in PCR capability, maintenance of high fidelity and retention of the superior thermostability associated with Pfu-Pol. However, even the arginine/thumb swap mutant falls short of Tkod-Pol in PCR, suggesting further improvement within the Pfu-Pol framework is attainable. The significance of this work is the observation that improvements in PCR performance are easily attainable by blending elements from closely related archaeal polymerases, an approach that may, in future, be extended by using more polymerases from these organisms.

  18. Probing Conformational Changes of Human DNA Polymerase λ Using Mass Spectrometry-Based Protein Footprinting

    Science.gov (United States)

    Fowler, Jason D.; Brown, Jessica A.; Kvaratskhelia, Mamuka; Suo, Zucai

    2009-01-01

    SUMMARY Crystallographic studies of the C-terminal, DNA polymerase β-like domain of human DNA polymerase lambda (fPolλ) suggested that the catalytic cycle might not involve a large protein domain rearrangement as observed with several replicative DNA polymerases and DNA polymerase β. To examine solution-phase protein conformation changes in fPolλ, which also contains a breast cancer susceptibility gene 1 C-terminal domain and a Proline-rich domain at its N-terminus, we used a mass spectrometry - based protein footprinting approach. In parallel experiments, surface accessibility maps for Arg residues were compared for the free fPolλ versus the binary complex of enzyme•gapped DNA and the ternary complex of enzyme•gapped DNA•dNTP. These experiments suggested that fPolλ does not undergo major conformational changes during the catalysis in the solution phase. Furthermore, the mass spectrometry-based protein footprinting experiments revealed that active site residue R386 was shielded from the surface only in the presence of both a gapped DNA substrate and an incoming nucleotide dNTP. Site-directed mutagenesis and pre-steady state kinetic studies confirmed the importance of R386 for the enzyme activity, and indicated the key role for its guanidino group in stabilizing the negative charges of an incoming nucleotide and the leaving pyrophosphate product. We suggest that such interactions could be shared by and important for catalytic functions of other DNA polymerases. PMID:19467241

  19. DNA polymerase η modulates replication fork progression and DNA damage responses in platinum-treated human cells

    Science.gov (United States)

    Sokol, Anna M.; Cruet-Hennequart, Séverine; Pasero, Philippe; Carty, Michael P.

    2013-11-01

    Human cells lacking DNA polymerase η (polη) are sensitive to platinum-based cancer chemotherapeutic agents. Using DNA combing to directly investigate the role of polη in bypass of platinum-induced DNA lesions in vivo, we demonstrate that nascent DNA strands are up to 39% shorter in human cells lacking polη than in cells expressing polη. This provides the first direct evidence that polη modulates replication fork progression in vivo following cisplatin and carboplatin treatment. Severe replication inhibition in individual platinum-treated polη-deficient cells correlates with enhanced phosphorylation of the RPA2 subunit of replication protein A on serines 4 and 8, as determined using EdU labelling and immunofluorescence, consistent with formation of DNA strand breaks at arrested forks in the absence of polη. Polη-mediated bypass of platinum-induced DNA lesions may therefore represent one mechanism by which cancer cells can tolerate platinum-based chemotherapy.

  20. Lesion Orientation of O4-Alkylthymidine Influences Replication by Human DNA Polymerase η.

    Science.gov (United States)

    O'Flaherty, D K; Patra, A; Su, Y; Guengerich, F P; Egli, M; Wilds, C J

    2016-08-01

    DNA lesions that elude repair may undergo translesion synthesis catalyzed by Y-family DNA polymerases. O 4 -Alkylthymidines, persistent adducts that can result from carcinogenic agents, may be encountered by DNA polymerases. The influence of lesion orientation around the C4- O 4 bond on processing by human DNA polymerase η (hPol η ) was studied for oligonucleotides containing O 4 -methylthymidine, O 4 -ethylthymidine, and analogs restricting the O 4 -methylene group in an anti -orientation. Primer extension assays revealed that the O 4 -alkyl orientation influences hPol η bypass. Crystal structures of hPol η •DNA•dNTP ternary complexes with O 4 -methyl- or O 4 -ethylthymidine in the template strand showed the nucleobase of the former lodged near the ceiling of the active site, with the syn - O 4 -methyl group engaged in extensive hydrophobic interactions. This unique arrangement for O 4 -methylthymidine with hPol η , inaccessible for the other analogs due to steric/conformational restriction, is consistent with differences observed for nucleotide incorporation and supports the concept that lesion conformation influences extension across DNA damage. Together, these results provide mechanistic insights on the mutagenicity of O 4 MedT and O 4 EtdT when acted upon by hPol η .

  1. DNA polymerase η mutational signatures are found in a variety of different types of cancer.

    Science.gov (United States)

    Rogozin, Igor B; Goncearenco, Alexander; Lada, Artem G; De, Subhajyoti; Yurchenko, Vyacheslav; Nudelman, German; Panchenko, Anna R; Cooper, David N; Pavlov, Youri I

    2018-01-01

    DNA polymerase (pol) η is a specialized error-prone polymerase with at least two quite different and contrasting cellular roles: to mitigate the genetic consequences of solar UV irradiation, and promote somatic hypermutation in the variable regions of immunoglobulin genes. Misregulation and mistargeting of pol η can compromise genome integrity. We explored whether the mutational signature of pol η could be found in datasets of human somatic mutations derived from normal and cancer cells. A substantial excess of single and tandem somatic mutations within known pol η mutable motifs was noted in skin cancer as well as in many other types of human cancer, suggesting that somatic mutations in A:T bases generated by DNA polymerase η are a common feature of tumorigenesis. Another peculiarity of pol ηmutational signatures, mutations in YCG motifs, led us to speculate that error-prone DNA synthesis opposite methylated CpG dinucleotides by misregulated pol η in tumors might constitute an additional mechanism of cytosine demethylation in this hypermutable dinucleotide.

  2. Structural basis for the suppression of skin cancers by DNA polymerase [eta

    Energy Technology Data Exchange (ETDEWEB)

    Silverstein, Timothy D.; Johnson, Robert E.; Jain, Rinku; Prakash, Louise; Prakash, Satya; Aggarwal, Aneel K. (Texas-MED); (Mount Sinai Hospital)

    2010-09-13

    DNA polymerase {eta} (Pol{eta}) is unique among eukaryotic polymerases in its proficient ability for error-free replication through ultraviolet-induced cyclobutane pyrimidine dimers, and inactivation of Pol{eta} (also known as POLH) in humans causes the variant form of xeroderma pigmentosum (XPV). We present the crystal structures of Saccharomyces cerevisiae Pol{eta} (also known as RAD30) in ternary complex with a cis-syn thymine-thymine (T-T) dimer and with undamaged DNA. The structures reveal that the ability of Pol{eta} to replicate efficiently through the ultraviolet-induced lesion derives from a simple and yet elegant mechanism, wherein the two Ts of the T-T dimer are accommodated in an active site cleft that is much more open than in other polymerases. We also show by structural, biochemical and genetic analysis that the two Ts are maintained in a stable configuration in the active site via interactions with Gln55, Arg73 and Met74. Together, these features define the basis for Pol{eta}'s action on ultraviolet-damaged DNA that is crucial in suppressing the mutagenic and carcinogenic consequences of sun exposure, thereby reducing the incidence of skin cancers in humans.

  3. Comparison of the kinetic parameters of the truncated catalytic subunit and holoenzyme of human DNA polymerase ε

    Science.gov (United States)

    Zahurancik, Walter J.; Baranovskiy, Andrey G.; Tahirov, Tahir H.; Suo, Zucai

    2015-01-01

    Numerous genetic studies have provided compelling evidence to establish DNA polymerase ε (Polε) as the primary DNA polymerase responsible for leading strand synthesis during eukaryotic nuclear genome replication. Polε is a heterotetramer consisting of a large catalytic subunit that contains the conserved polymerase core domain as well as a 3′ → 5′ exonuclease domain common to many replicative polymerases. In addition, Polε possesses three small subunits that lack a known catalytic activity but associate with components involved in a variety of DNA replication and maintenance processes. Previous enzymatic characterization of the Polε heterotetramer from budding yeast suggested that the small subunits slightly enhance DNA synthesis by Polε in vitro. However, similar studies of the human Polε heterote-tramer (hPolε) have been limited by the difficulty of obtaining hPolε in quantities suitable for thorough investigation of its catalytic activity. Utilization of a baculovirus expression system for overexpression and purification of hPolε from insect host cells has allowed for isolation of greater amounts of active hPolε, thus enabling a more detailed kinetic comparison between hPolε and an active N-terminal fragment of the hPolε catalytic subunit (p261N), which is readily overexpressed in Escherichia coli. Here, we report the first pre-steady-state studies of fully-assembled hPolε. We observe that the small subunits increase DNA binding by hPolε relative to p261N, but do not increase processivity during DNA synthesis on a single-stranded M13 template. Interestingly, the 3′ → 5′ exonuclease activity of hPolε is reduced relative to p261N on matched and mismatched DNA substrates, indicating that the presence of the small subunits may regulate the proofreading activity of hPolε and sway hPolε toward DNA synthesis rather than proofreading. PMID:25684708

  4. Repriming by PrimPol is critical for DNA replication restart downstream of lesions and chain-terminating nucleosides.

    Science.gov (United States)

    Kobayashi, Kaori; Guilliam, Thomas A; Tsuda, Masataka; Yamamoto, Junpei; Bailey, Laura J; Iwai, Shigenori; Takeda, Shunichi; Doherty, Aidan J; Hirota, Kouji

    2016-08-02

    PrimPol is a DNA damage tolerance enzyme possessing both translesion synthesis (TLS) and primase activities. To uncover its potential role in TLS-mediated IgVλ hypermutation and define its interplay with other TLS polymerases, PrimPol(-/-) and PrimPol(-/-)/Polη(-/-)/Polζ (-/-) gene knockouts were generated in avian cells. Loss of PrimPol had no significant impact on the rate of hypermutation or the mutation spectrum of IgVλ. However, PrimPol(-/-) cells were sensitive to methylmethane sulfonate, suggesting that it may bypass abasic sites at the IgVλ segment by repriming DNA synthesis downstream of these sites. PrimPol(-/-) cells were also sensitive to cisplatin and hydroxyurea, indicating that it assists in maintaining / restarting replication at a variety of lesions. To accurately measure the relative contribution of the TLS and primase activities, we examined DNA damage sensitivity in PrimPol(-/-) cells complemented with polymerase or primase-deficient PrimPol. Polymerase-defective, but not primase-deficient, PrimPol suppresses the hypersensitivity of PrimPol(-/-) cells. This indicates that its primase, rather than TLS activity, is pivotal for DNA damage tolerance. Loss of TLS polymerases, Polη and Polζ has an additive effect on the sensitivity of PrimPol(-/-) cells. Moreover, we found that PrimPol and Polη-Polζ redundantly prevented cell death and facilitated unperturbed cell cycle progression. PrimPol(-/-) cells also exhibited increased sensitivity to a wide variety of chain-terminating nucleoside analogs (CTNAs). PrimPol could perform close-coupled repriming downstream of CTNAs and oxidative damage in vitro. Together, these results indicate that PrimPol's repriming activity plays a central role in reinitiating replication downstream from CTNAs and other specific DNA lesions.

  5. Excision-repair in mutants of Escherichia coli deficient in DNA polymerase I and/or its associated 5'. -->. 3' exonuclease

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, P [Stanford Univ., Calif. (USA). Dept. of Biological Sciences

    1977-01-01

    The UV sensitivity of E.coli mutants deficient in the 5'..-->..3' exonuclease activity of DNA polymerase I is intermediate between that of pol/sup +/ strains and mutants which are deficient in the polymerizing activity of pol I (polA1). Like polA1 mutants, the 5'-econuclease deficient mutants exhibit increased UV-induced DNA degradation and increased repair synthesis compared to a pol/sup +/ strain, although the increase is not as great as in polA1 or in the conditionally lethal mutant BT4113ts deficient in both polymerase I activities. When dimer excision was measured at UV doses low enough to avoid interference from extensive DNA degradation, all three classes of polymerase I deficient mutants were found to remove dimers efficiently from their DNA. We conclude that enzymes alternative to polymerase I can operate in both the excision and resynthesis steps of excision repair and that substitution for either of the polymerase I functions results in longer patches of repair. A model is proposed detailing the possible events in the alternative pathways.

  6. Mechanism of Error-Free DNA Replication Past Lucidin-Derived DNA Damage by Human DNA Polymerase κ.

    Science.gov (United States)

    Yockey, Oliver P; Jha, Vikash; Ghodke, Pratibha P; Xu, Tianzuo; Xu, Wenyan; Ling, Hong; Pradeepkumar, P I; Zhao, Linlin

    2017-11-20

    DNA damage impinges on genetic information flow and has significant implications in human disease and aging. Lucidin-3-O-primeveroside (LuP) is an anthraquinone derivative present in madder root, which has been used as a coloring agent and food additive. LuP can be metabolically converted to genotoxic compound lucidin, which subsequently forms lucidin-specific N 2 -2'-deoxyguanosine (N 2 -dG) and N 6 -2'-deoxyadenosine (N 6 -dA) DNA adducts. Lucidin is mutagenic and carcinogenic in rodents but has low carcinogenic risks in humans. To understand the molecular mechanism of low carcinogenicity of lucidin in humans, we performed DNA replication assays using site-specifically modified oligodeoxynucleotides containing a structural analogue (LdG) of lucidin-N 2 -dG DNA adduct and determined the crystal structures of DNA polymerase (pol) κ in complex with LdG-bearing DNA and an incoming nucleotide. We examined four human pols (pol η, pol ι, pol κ, and Rev1) in their efficiency and accuracy during DNA replication with LdG; these pols are key players in translesion DNA synthesis. Our results demonstrate that pol κ efficiently and accurately replicates past the LdG adduct, whereas DNA replication by pol η, pol ι is compromised to different extents. Rev1 retains its ability to incorporate dCTP opposite the lesion albeit with decreased efficiency. Two ternary crystal structures of pol κ illustrate that the LdG adduct is accommodated by pol κ at the enzyme active site during insertion and postlesion-extension steps. The unique open active site of pol κ allows the adducted DNA to adopt a standard B-form for accurate DNA replication. Collectively, these biochemical and structural data provide mechanistic insights into the low carcinogenic risk of lucidin in humans.

  7. Competitive fitness during feast and famine: how SOS DNA polymerases influence physiology and evolution in Escherichia coli.

    Science.gov (United States)

    Corzett, Christopher H; Goodman, Myron F; Finkel, Steven E

    2013-06-01

    Escherichia coli DNA polymerases (Pol) II, IV, and V serve dual roles by facilitating efficient translesion DNA synthesis while simultaneously introducing genetic variation that can promote adaptive evolution. Here we show that these alternative polymerases are induced as cells transition from exponential to long-term stationary-phase growth in the absence of induction of the SOS regulon by external agents that damage DNA. By monitoring the relative fitness of isogenic mutant strains expressing only one alternative polymerase over time, spanning hours to weeks, we establish distinct growth phase-dependent hierarchies of polymerase mutant strain competitiveness. Pol II confers a significant physiological advantage by facilitating efficient replication and creating genetic diversity during periods of rapid growth. Pol IV and Pol V make the largest contributions to evolutionary fitness during long-term stationary phase. Consistent with their roles providing both a physiological and an adaptive advantage during stationary phase, the expression patterns of all three SOS polymerases change during the transition from log phase to long-term stationary phase. Compared to the alternative polymerases, Pol III transcription dominates during mid-exponential phase; however, its abundance decreases to SOS induction by exogenous agents and indicate that cell populations require appropriate expression of all three alternative DNA polymerases during exponential, stationary, and long-term stationary phases to attain optimal fitness and undergo adaptive evolution.

  8. Identification of Critical Residues for the Tight Binding of Both Correct and Incorrect Nucleotides to Human DNA Polymerase λ

    Science.gov (United States)

    Brown, Jessica A.; Pack, Lindsey R.; Sherrer, Shanen M.; Kshetry, Ajay K.; Newmister, Sean A.; Fowler, Jason D.; Taylor, John-Stephen; Suo, Zucai

    2010-01-01

    DNA polymerase λ (Pol λ) is a novel X-family DNA polymerase that shares 34% sequence identity with DNA polymerase β (Pol β). Pre-steady state kinetic studies have shown that the Pol λ•DNA complex binds both correct and incorrect nucleotides 130-fold tighter on average than the Pol β•DNA complex, although, the base substitution fidelity of both polymerases is 10−4 to 10−5. To better understand Pol λ’s tight nucleotide binding affinity, we created single- and double-substitution mutants of Pol λ to disrupt interactions between active site residues and an incoming nucleotide or a template base. Single-turnover kinetic assays showed that Pol λ binds to an incoming nucleotide via cooperative interactions with active site residues (R386, R420, K422, Y505, F506, A510, and R514). Disrupting protein interactions with an incoming correct or incorrect nucleotide impacted binding with each of the common structural moieties in the following order: triphosphate ≫ base > ribose. In addition, the loss of Watson-Crick hydrogen bonding between the nucleotide and template base led to a moderate increase in the Kd. The fidelity of Pol λ was maintained predominantly by a single residue, R517, which has minor groove interactions with the DNA template. PMID:20851705

  9. Lesion Orientation of O4-Alkylthymidine Influences Replication by Human DNA Polymerase η

    OpenAIRE

    O’Flaherty, D. K.; Patra, A.; Su, Y.; Guengerich, F. P.; Egli, M.; Wilds, C. J.

    2016-01-01

    DNA lesions that elude repair may undergo translesion synthesis catalyzed by Y-family DNA polymerases. O4-Alkylthymidines, persistent adducts that can result from carcinogenic agents, may be encountered by DNA polymerases. The influence of lesion orientation around the C4-O4 bond on processing by human DNA polymerase η (hPol η) was studied for oligonucleotides containing O4-methylthymidine, O4-ethylthymidine, and analogs restricting the O4-methylene group in an anti-orientation. Primer extens...

  10. Human Pol ζ purified with accessory subunits is active in translesion DNA synthesis and complements Pol η in cisplatin bypass.

    Science.gov (United States)

    Lee, Young-Sam; Gregory, Mark T; Yang, Wei

    2014-02-25

    DNA polymerase ζ (Pol ζ) is a eukaryotic B-family DNA polymerase that specializes in translesion synthesis and is essential for normal embryogenesis. At a minimum, Pol ζ consists of a catalytic subunit Rev3 and an accessory subunit Rev7. Mammalian Rev3 contains >3,000 residues and is twice as large as the yeast homolog. To date, no vertebrate Pol ζ has been purified for biochemical characterization. Here we report purification of a series of human Rev3 deletion constructs expressed in HEK293 cells and identification of a minimally catalytically active human Pol ζ variant. With a tagged form of an active Pol ζ variant, we isolated two additional accessory subunits of human Pol ζ, PolD2 and PolD3. The purified four-subunit Pol ζ4 (Rev3-Rev7-PolD2-PolD3) is much more efficient and more processive at bypassing a 1,2-intrastrand d(GpG)-cisplatin cross-link than the two-subunit Pol ζ2 (Rev3-Rev7). We show that complete bypass of cisplatin lesions requires Pol η to insert dCTP opposite the 3' guanine and Pol ζ4 to extend the primers.

  11. Characterization of a Y-Family DNA Polymerase eta from the Eukaryotic Thermophile Alvinella pompejana

    Science.gov (United States)

    Kashiwagi, Sayo; Kuraoka, Isao; Fujiwara, Yoshie; Hitomi, Kenichi; Cheng, Quen J.; Fuss, Jill O.; Shin, David S.; Masutani, Chikahide; Tainer, John A.; Hanaoka, Fumio; Iwai, Shigenori

    2010-01-01

    Human DNA polymerase η (HsPolη) plays an important role in translesion synthesis (TLS), which allows for replication past DNA damage such as UV-induced cis-syn cyclobutane pyrimidine dimers (CPDs). Here, we characterized ApPolη from the thermophilic worm Alvinella pompejana, which inhabits deep-sea hydrothermal vent chimneys. ApPolη shares sequence homology with HsPolη and contains domains for binding ubiquitin and proliferating cell nuclear antigen. Sun-induced UV does not penetrate Alvinella's environment; however, this novel DNA polymerase catalyzed efficient and accurate TLS past CPD, as well as 7,8-dihydro-8-oxoguanine and isomers of thymine glycol induced by reactive oxygen species. In addition, we found that ApPolη is more thermostable than HsPolη, as expected from its habitat temperature. Moreover, the activity of this enzyme was retained in the presence of a higher concentration of organic solvents. Therefore, ApPolη provides a robust, human-like Polη that is more active after exposure to high temperatures and organic solvents. PMID:20936172

  12. Two DNA polymerase sliding clamps from the thermophilic archaeon Sulfolobus solfataricus.

    Science.gov (United States)

    De Felice, M; Sensen, C W; Charlebois, R L; Rossi, M; Pisani, F M

    1999-08-06

    Herein, we report the identification and characterization of two DNA polymerase processivity factors from the thermoacidophilic archaeon Sulfolobus solfataricus. They, referred to as 039p (244 amino acid residues, 27 kDa) and 048p (249 amino acid residues, 27 kDa), present significant primary structure similarity to eukaryotic proliferating cell nuclear antigen (PCNA). We demonstrate that both 039p and 048p form oligomers in solution and are able to substantially activate the synthetic activity of the single-subunit family B DNA polymerase from S. solfataricus (Sso DNA pol B1) on poly(dA)-oligo(dT) as a primer-template. This stimulatory effect is the result of enhanced DNA polymerase processivity, as indicated by the analysis of the elongation products on polyacrylamide gels. Activation of Sso DNA pol B1 synthetic activity was also observed on linear primed single-stranded M13 mp18 DNA as a template. By immunoblot analysis using specific rabbit antisera, 039p and 048p were both detected in the logarithmic and stationary phases of S. solfataricus growth curve. This is the first report of the identification and biochemical characterization of two distinct DNA polymerase processivity factors from the same organism. The significance of these findings for the understanding of the DNA replication process in Archaea is discussed. Copyright 1999 Academic Press.

  13. Functional Analysis of Cancer-Associated DNA Polymerase ε Variants in Saccharomyces cerevisiae

    Directory of Open Access Journals (Sweden)

    Stephanie R. Barbari

    2018-03-01

    Full Text Available DNA replication fidelity relies on base selectivity of the replicative DNA polymerases, exonucleolytic proofreading, and postreplicative DNA mismatch repair (MMR. Ultramutated human cancers without MMR defects carry alterations in the exonuclease domain of DNA polymerase ε (Polε. They have been hypothesized to result from defective proofreading. However, modeling of the most common variant, Polε-P286R, in yeast produced an unexpectedly strong mutator effect that exceeded the effect of proofreading deficiency by two orders of magnitude and indicated the involvement of other infidelity factors. The in vivo consequences of many additional Polε mutations reported in cancers remain poorly understood. Here, we genetically characterized 13 cancer-associated Polε variants in the yeast system. Only variants directly altering the DNA binding cleft in the exonuclease domain elevated the mutation rate. Among these, frequently recurring variants were stronger mutators than rare variants, in agreement with the idea that mutator phenotype has a causative role in tumorigenesis. In nearly all cases, the mutator effects exceeded those of an exonuclease-null allele, suggesting that mechanisms distinct from loss of proofreading may drive the genome instability in most ultramutated tumors. All mutator alleles were semidominant, supporting the view that heterozygosity for the polymerase mutations is sufficient for tumor development. In contrast to the DNA binding cleft alterations, peripherally located variants, including a highly recurrent V411L, did not significantly elevate mutagenesis. Finally, the analysis of Polε variants found in MMR-deficient tumors suggested that the majority cause no mutator phenotype alone but some can synergize with MMR deficiency to increase the mutation rate.

  14. Sub-nuclear irradiation, in-vivo microscopy and single-molecule imaging to study a DNA Polymerase

    Energy Technology Data Exchange (ETDEWEB)

    Soria, G; Mansilla, S; Belluscio, L; Speroni, J; D' Alessio, C; Gottifredi, V [Fundacion Leloir, Buenos Aires (Argentina); Essers, J; Kanaar, R [Erasmus Medical Center, Rotterdam (Netherlands)

    2009-07-01

    When the DNA is damaged in cells progressing through S phase, replication blockage can be avoided by TLS (Translesion DNA synthesis). This is an auxiliary replication mechanism that relies on the function of specialized polymerases that accomplish DNA damage bypass. An example of a classical TLS polymerase is Pol {eta} ({eta}). The current model implies that Pol {eta} activity is circumscribed to S-phase. Here we perform a systematic characterization of Pol {eta} behaviour after DNA-damage. We show that Pol {eta} is recruited to UV-induced DNA lesions in cells outside S phase including cells permanently arrested in G1. This observation was confirmed by different sub-nuclear damage strategies including global UV irradiation, local UV irradiation and local multi-photon laser irradiation of single nuclei in living cells. By local UV irradiation and alpha particle irradiation we evaluated the potential connection between Pol h recruitment to DNA lesions outside S phase and Homologous recombination repair (HRR) or Nucleotide excision repair (NER). Finally, we employ a single-molecule imaging approach (known as DNA fiber-assay) to determine how Pol h influences the progression of the replication fork. Our data reveals that the re-localization of Pol {eta} to DNA lesions might be temporally and mechanistically uncoupled from replicative DNA synthesis and from DNA damage processing. (authors)

  15. Sub-nuclear irradiation, in-vivo microscopy and single-molecule imaging to study a DNA Polymerase

    International Nuclear Information System (INIS)

    Soria, G.; Mansilla, S.; Belluscio, L.; Speroni, J.; D'Alessio, C.; Gottifredi, V.; Essers, J.; Kanaar, R.

    2009-01-01

    When the DNA is damaged in cells progressing through S phase, replication blockage can be avoided by TLS (Translesion DNA synthesis). This is an auxiliary replication mechanism that relies on the function of specialized polymerases that accomplish DNA damage bypass. An example of a classical TLS polymerase is Pol η (eta). The current model implies that Pol η activity is circumscribed to S-phase. Here we perform a systematic characterization of Pol η behaviour after DNA-damage. We show that Pol η is recruited to UV-induced DNA lesions in cells outside S phase including cells permanently arrested in G1. This observation was confirmed by different sub-nuclear damage strategies including global UV irradiation, local UV irradiation and local multi-photon laser irradiation of single nuclei in living cells. By local UV irradiation and alpha particle irradiation we evaluated the potential connection between Pol h recruitment to DNA lesions outside S phase and Homologous recombination repair (HRR) or Nucleotide excision repair (NER). Finally, we employ a single-molecule imaging approach (known as DNA fiber-assay) to determine how Pol h influences the progression of the replication fork. Our data reveals that the re-localization of Pol η to DNA lesions might be temporally and mechanistically uncoupled from replicative DNA synthesis and from DNA damage processing. (authors)

  16. Escherichia coli DNA polymerase I can disrupt G-quadruplex structures during DNA replication.

    Science.gov (United States)

    Teng, Fang-Yuan; Hou, Xi-Miao; Fan, San-Hong; Rety, Stephane; Dou, Shuo-Xing; Xi, Xu-Guang

    2017-12-01

    Non-canonical four-stranded G-quadruplex (G4) DNA structures can form in G-rich sequences that are widely distributed throughout the genome. The presence of G4 structures can impair DNA replication by hindering the progress of replicative polymerases (Pols), and failure to resolve these structures can lead to genetic instability. In the present study, we combined different approaches to address the question of whether and how Escherichia coli Pol I resolves G4 obstacles during DNA replication and/or repair. We found that E. coli Pol I-catalyzed DNA synthesis could be arrested by G4 structures at low protein concentrations and the degree of inhibition was strongly dependent on the stability of the G4 structures. Interestingly, at high protein concentrations, E. coli Pol I was able to overcome some kinds of G4 obstacles without the involvement of other molecules and could achieve complete replication of G4 DNA. Mechanistic studies suggested that multiple Pol I proteins might be implicated in G4 unfolding, and the disruption of G4 structures requires energy derived from dNTP hydrolysis. The present work not only reveals an unrealized function of E. coli Pol I, but also presents a possible mechanism by which G4 structures can be resolved during DNA replication and/or repair in E. coli. © 2017 Federation of European Biochemical Societies.

  17. Effect of human cell malignancy on activity of DNA polymerase iota.

    Science.gov (United States)

    Kazakov, A A; Grishina, E E; Tarantul, V Z; Gening, L V

    2010-07-01

    An increased level of mutagenesis, partially caused by imbalanced activities of error prone DNA polymerases, is a key symptom of cell malignancy. To clarify the possible role of incorrect DNA polymerase iota (Pol iota) function in increased frequency of mutations in mammalian cells, the activity of this enzyme in extracts of cells of different mouse organs and human eye (melanoma) and eyelid (basal-cell skin carcinoma) tumor cells was studied. Both Mg2+, considered as the main activator of the enzyme reaction of in vivo DNA replication, and Mn2+, that activates homogeneous Pol iota preparations in experiments in vitro more efficiently compared to all other bivalent cations, were used as cofactors of the DNA polymerase reaction in these experiments. In the presence of Mg2+, the enzyme was active only in cell extracts of mouse testicles and brain, whereas in the presence of Mn2+ the activity of Pol iota was found in all studied normal mouse organs. It was found that in cell extracts of both types of malignant tumors (basal-cell carcinoma and melanoma) Pol iota activity was observed in the presence of either Mn2+ or Mg2+. Manganese ions activated Pol iota in both cases, though to a different extent. In the presence of Mn2+ the Pol iota activity in the basal-cell carcinoma exceeded 2.5-fold that in control cells (benign tumors from the same eyelid region). In extracts of melanoma cells in the presence of either cation, the level of the enzyme activity was approximately equal to that in extracts of cells of surrounding tumor-free tissues as well as in eyes removed after traumas. The distinctive feature of tissue malignancy (in basal-cell carcinoma and in melanoma) was the change in DNA synthesis revealed as Mn2+-activated continuation of DNA synthesis after incorrect incorporation of dG opposite dT in the template by Pol iota. Among cell extracts of different normal mouse organs, only those of testicles exhibited a similar feature. This similarity can be explained by

  18. The role of DNA polymerase ζ in translesion synthesis across bulky DNA adducts and cross-links in human cells

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Tetsuya, E-mail: suzukite@hiroshima-u.ac.jp [Division of Genetics and Mutagenesis, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501 (Japan); Grúz, Petr; Honma, Masamitsu [Division of Genetics and Mutagenesis, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501 (Japan); Adachi, Noritaka [Graduate School of Nanobioscience, Yokohama City University, 22-2 Seto, Kanazawa-ku, Yokohama 236-0027 (Japan); Nohmi, Takehiko [Division of Genetics and Mutagenesis, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501 (Japan)

    2016-09-15

    Highlights: • Human cells knockout (KO) and expressing catalytically dead (CD) variant of DNA polymerase ζ (Pol ζ) have been established by gene targeting techniques with Nalm-6 cells. • Both Pol ζ KO and CD cells displayed prolonged cell cycle and higher incidence of micronucleus formation than the wild-type cells in the absence of exogenous genotoxic treatments. • Pol ζ protects human cells from genotoxic stresses that induce bulky DNA lesions and cross-links. • Pol ζ plays quite limited roles in protection against strand-breaks in DNA. - Abstract: Translesion DNA synthesis (TLS) is a cellular defense mechanism against genotoxins. Defects or mutations in specialized DNA polymerases (Pols) involved in TLS are believed to result in hypersensitivity to various genotoxic stresses. Here, DNA polymerase ζ (Pol ζ)-deficient (KO: knockout) and Pol ζ catalytically dead (CD) human cells were established and their sensitivity towards cytotoxic activities of various genotoxins was examined. The CD cells were engineered by altering the DNA sequence encoding two amino acids essential for the catalytic activity of Pol ζ, i.e., D2781 and D2783, to alanines. Both Pol ζ KO and CD cells displayed a prolonged cell cycle and higher incidence of micronuclei formation than the wild-type (WT) cells in the absence of exogenous genotoxic treatments, and the order of abnormality was CD > KO > WT cells. Both KO and CD cells exhibited higher sensitivity towards the killing effects of benzo[a]pyrene diol epoxide, mitomycin C, potassium bromate, N-methyl-N′-nitro-N-nitrosoguanidine, and ultraviolet C irradiation than WT cells, and there were no differences between the sensitivities of KO and CD cells. Interestingly, neither KO nor CD cells were sensitive to the cytotoxic effects of hydrogen peroxide. Since KO and CD cells displayed similar sensitivities to the genotoxins, we employed only KO cells to further examine their sensitivity to other genotoxic agents. KO cells were

  19. The role of DNA polymerase ζ in translesion synthesis across bulky DNA adducts and cross-links in human cells

    International Nuclear Information System (INIS)

    Suzuki, Tetsuya; Grúz, Petr; Honma, Masamitsu; Adachi, Noritaka; Nohmi, Takehiko

    2016-01-01

    Highlights: • Human cells knockout (KO) and expressing catalytically dead (CD) variant of DNA polymerase ζ (Pol ζ) have been established by gene targeting techniques with Nalm-6 cells. • Both Pol ζ KO and CD cells displayed prolonged cell cycle and higher incidence of micronucleus formation than the wild-type cells in the absence of exogenous genotoxic treatments. • Pol ζ protects human cells from genotoxic stresses that induce bulky DNA lesions and cross-links. • Pol ζ plays quite limited roles in protection against strand-breaks in DNA. - Abstract: Translesion DNA synthesis (TLS) is a cellular defense mechanism against genotoxins. Defects or mutations in specialized DNA polymerases (Pols) involved in TLS are believed to result in hypersensitivity to various genotoxic stresses. Here, DNA polymerase ζ (Pol ζ)-deficient (KO: knockout) and Pol ζ catalytically dead (CD) human cells were established and their sensitivity towards cytotoxic activities of various genotoxins was examined. The CD cells were engineered by altering the DNA sequence encoding two amino acids essential for the catalytic activity of Pol ζ, i.e., D2781 and D2783, to alanines. Both Pol ζ KO and CD cells displayed a prolonged cell cycle and higher incidence of micronuclei formation than the wild-type (WT) cells in the absence of exogenous genotoxic treatments, and the order of abnormality was CD > KO > WT cells. Both KO and CD cells exhibited higher sensitivity towards the killing effects of benzo[a]pyrene diol epoxide, mitomycin C, potassium bromate, N-methyl-N′-nitro-N-nitrosoguanidine, and ultraviolet C irradiation than WT cells, and there were no differences between the sensitivities of KO and CD cells. Interestingly, neither KO nor CD cells were sensitive to the cytotoxic effects of hydrogen peroxide. Since KO and CD cells displayed similar sensitivities to the genotoxins, we employed only KO cells to further examine their sensitivity to other genotoxic agents. KO cells were

  20. Human DNA polymerase delta double-mutant D316A;E318A interferes with DNA mismatch repair in vitro

    DEFF Research Database (Denmark)

    Liu, Dekang; Frederiksen, Jane H.; Liberti, Sascha Emilie

    2017-01-01

    DNA mismatch repair (MMR) is a highly-conserved DNA repair mechanism, whose primary role is to remove DNA replication errors preventing them from manifesting as mutations, thereby increasing the overall genome stability. Defects in MMR are associated with increased cancer risk in humans and other...... organisms. Here, we characterize the interaction between MMR and a proofreading-deficient allele of the human replicative DNA polymerase delta, PolδD316A;E318A, which has a higher capacity for strand displacement DNA synthesis than wild type Polδ. Human cell lines overexpressing PolδD316A;E318A display...

  1. Alternative splicing at exon 2 results in the loss of the catalytic activity of mouse DNA polymerase iota in vitro.

    Science.gov (United States)

    Kazachenko, Konstantin Y; Miropolskaya, Nataliya A; Gening, Leonid V; Tarantul, Vyacheslav Z; Makarova, Alena V

    2017-02-01

    Y-family DNA polymerase iota (Pol ι) possesses both DNA polymerase and dRP lyase activities and was suggested to be involved in DNA translesion synthesis and base excision repair in mammals. The 129 strain of mice and its derivatives have a natural nonsense codon mutation in the second exon of the Pol ι gene resulting in truncation of the Pol ι protein. These mice were widely used as a Pol ι-null model for in vivo studies of the Pol ι function. However whether 129-derived strains of mice are fully deficient in the Pol ι functions was a subject of discussion since Pol ι mRNA undergoes alternative splicing at exon 2. Here we report purification of mouse Pol ι lacking the region encoded by exon 2, which includes several conserved residues involved in catalysis. We show that the deletion abrogates both the DNA polymerase and dRP lyase activities of Pol ι in the presence of either Mg 2+ or Mn 2+ ions. Thus, 129-derived strains of mice express catalytically inactive alternatively spliced Pol ι variant, whose cellular functions, if any exist, remain to be established. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. A Major Role of DNA Polymerase δ in Replication of Both the Leading and Lagging DNA Strands.

    Science.gov (United States)

    Johnson, Robert E; Klassen, Roland; Prakash, Louise; Prakash, Satya

    2015-07-16

    Genetic studies with S. cerevisiae Polδ (pol3-L612M) and Polε (pol2-M644G) mutant alleles, each of which display a higher rate for the generation of a specific mismatch, have led to the conclusion that Polε is the primary leading strand replicase and that Polδ is restricted to replicating the lagging strand template. Contrary to this widely accepted view, here we show that Polδ plays a major role in the replication of both DNA strands, and that the paucity of pol3-L612M-generated errors on the leading strand results from their more proficient removal. Thus, the apparent lack of Polδ contribution to leading strand replication is due to differential mismatch removal rather than differential mismatch generation. Altogether, our genetic studies with Pol3 and Pol2 mutator alleles support the conclusion that Polδ, and not Polε, is the major DNA polymerase for carrying out both leading and lagging DNA synthesis. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Characterization of DNA polymerase X from Thermus thermophilus HB8 reveals the POLXc and PHP domains are both required for 3'-5' exonuclease activity.

    Science.gov (United States)

    Nakane, Shuhei; Nakagawa, Noriko; Kuramitsu, Seiki; Masui, Ryoji

    2009-04-01

    The X-family DNA polymerases (PolXs) comprise a highly conserved DNA polymerase family found in all kingdoms. Mammalian PolXs are known to be involved in several DNA-processing pathways including repair, but the cellular functions of bacterial PolXs are less known. Many bacterial PolXs have a polymerase and histidinol phosphatase (PHP) domain at their C-termini in addition to a PolX core (POLXc) domain, and possess 3'-5' exonuclease activity. Although both domains are highly conserved in bacteria, their molecular functions, especially for a PHP domain, are unknown. We found Thermus thermophilus HB8 PolX (ttPolX) has Mg(2+)/Mn(2+)-dependent DNA/RNA polymerase, Mn(2+)-dependent 3'-5' exonuclease and DNA-binding activities. We identified the domains of ttPolX by limited proteolysis and characterized their biochemical activities. The POLXc domain was responsible for the polymerase and DNA-binding activities but exonuclease activity was not detected for either domain. However, the POLXc and PHP domains interacted with each other and a mixture of the two domains had Mn(2+)-dependent 3'-5' exonuclease activity. Moreover, site-directed mutagenesis revealed catalytically important residues in the PHP domain for the 3'-5' exonuclease activity. Our findings provide a molecular insight into the functional domain organization of bacterial PolXs, especially the requirement of the PHP domain for 3'-5' exonuclease activity.

  4. DNA polymerase ι: The long and the short of it!

    Science.gov (United States)

    Frank, Ekaterina G; McLenigan, Mary P; McDonald, John P; Huston, Donald; Mead, Samantha; Woodgate, Roger

    2017-10-01

    The cDNA encoding human DNA polymerase ι (POLI) was cloned in 1999. At that time, it was believed that the POLI gene encoded a protein of 715 amino acids. Advances in DNA sequencing technologies led to the realization that there is an upstream, in-frame initiation codon that would encode a DNA polymerase ι (polι) protein of 740 amino acids. The extra 25 amino acid region is rich in acidic residues (11/25) and is reasonably conserved in eukaryotes ranging from fish to humans. As a consequence, the curated Reference Sequence (RefSeq) database identified polι as a 740 amino acid protein. However, the existence of the 740 amino acid polι has never been shown experimentally. Using highly specific antibodies to the 25 N-terminal amino acids of polι, we were unable to detect the longer 740 amino acid (ι-long) isoform in western blots. However, trace amounts of the ι-long isoform were detected after enrichment by immunoprecipitation. One might argue that the longer isoform may have a distinct biological function, if it exhibits significant differences in its enzymatic properties from the shorter, well-characterized 715 amino acid polι. We therefore purified and characterized recombinant full-length (740 amino acid) polι-long and compared it to full-length (715 amino acid) polι-short in vitro. The metal ion requirements for optimal catalytic activity differ slightly between ι-long and ι-short, but under optimal conditions, both isoforms exhibit indistinguishable enzymatic properties in vitro. We also report that like ι-short, the ι-long isoform can be monoubiquitinated and polyubiuquitinated in vivo, as well as form damage induced foci in vivo. We conclude that the predominant isoform of DNA polι in human cells is the shorter 715 amino acid protein and that if, or when, expressed, the longer 740 amino acid isoform has identical properties to the considerably more abundant shorter isoform. Published by Elsevier B.V.

  5. N-terminal domains of human DNA polymerase lambda promote primer realignment during translesion DNA synthesis

    Science.gov (United States)

    Taggart, David J.; Dayeh, Daniel M.; Fredrickson, Saul W.; Suo, Zucai

    2014-01-01

    The X-family DNA polymerases λ (Polλ) and β (Polβ) possess similar 5′-2-deoxyribose-5-phosphatelyase (dRPase) and polymerase domains. Besides these domains, Polλ also possesses a BRCA1 C-terminal (BRCT) domain and a proline-rich domain at its N terminus. However, it is unclear how these non-enzymatic domains contribute to the unique biological functions of Polλ. Here, we used primer extension assays and a newly developed high-throughput short oligonucleotide sequencing assay (HT-SOSA) to compare the efficiency of lesion bypass and fidelity of human Polβ, Polλ and two N-terminal deletion constructs of Polλ during the bypass of either an abasic site or a 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG) lesion. We demonstrate that the BRCT domain of Polλ enhances the efficiency of abasic site bypass by approximately 1.6-fold. In contrast, deletion of the N-terminal domains of Polλ did not affect the efficiency of 8-oxodG bypass relative to nucleotide incorporations opposite undamaged dG. HT-SOSA analysis demonstrated that Polλ and Polβ preferentially generated −1 or −2 frameshift mutations when bypassing an abasic site and the single or double base deletion frequency was highly sequence dependent. Interestingly, the BRCT and proline-rich domains of Polλ cooperatively promoted the generation of −2 frameshift mutations when the abasic site was situated within a sequence context that was susceptible to homology-driven primer realignment. Furthermore, both N-terminal domains of Polλ increased the generation of −1 frameshift mutations during 8-oxodG bypass and influenced the frequency of substitution mutations produced by Polλ opposite the 8-oxodG lesion. Overall, our data support a model wherein the BRCT and proline-rich domains of Polλ act cooperatively to promote primer/template realignment between DNA strands of limited sequence homology. This function of the N-terminal domains may facilitate the role of Polλ as a gap-filling polymerase

  6. Role of damage-specific DNA polymerases in M13 phage mutagenesis induced by a major lipid peroxidation product trans-4-hydroxy-2-nonenal

    Energy Technology Data Exchange (ETDEWEB)

    Janowska, Beata [Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5a, 02-106 Warsaw (Poland); Kurpios-Piec, Dagmara [Department of Biochemistry, Medical University of Warsaw, Banacha 1, 02-097 Warsaw (Poland); Prorok, Paulina [Institute of Genetics and Biotechnology, Warsaw University, Pawinskiego 5a, 02-106 Warsaw (Poland); Szparecki, Grzegorz [Medical University of Warsaw, Zwirki i Wigury 61, 02-097 Warsaw (Poland); Komisarski, Marek [Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5a, 02-106 Warsaw (Poland); Kowalczyk, Pawel [Interdisciplinary Centre for Mathematical and Computational Modelling, Warsaw University, Pawinskiego 5a, 02-106 Warsaw (Poland); Janion, Celina [Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5a, 02-106 Warsaw (Poland); Tudek, Barbara, E-mail: tudek@ibb.waw.pl [Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5a, 02-106 Warsaw (Poland); Institute of Genetics and Biotechnology, Warsaw University, Pawinskiego 5a, 02-106 Warsaw (Poland)

    2012-01-03

    One of the major lipid peroxidation products trans-4-hydroxy-2-nonenal (HNE), forms cyclic propano- or ethenoadducts bearing six- or seven-carbon atom side chains to G > C Much-Greater-Than A > T. To specify the role of SOS DNA polymerases in HNE-induced mutations, we tested survival and mutation spectra in the lacZ{alpha} gene of M13mp18 phage, whose DNA was treated in vitro with HNE, and which was grown in uvrA{sup -}Escherichia coli strains, carrying one, two or all three SOS DNA polymerases. When Pol IV was the only DNA SOS polymerase in the bacterial host, survival of HNE-treated M13 DNA was similar to, but mutation frequency was lower than in the strain containing all SOS DNA polymerases. When only Pol II or Pol V were present in host bacteria, phage survival decreased dramatically. Simultaneously, mutation frequency was substantially increased, but exclusively in the strain carrying only Pol V, suggesting that induction of mutations by HNE is mainly dependent on Pol V. To determine the role of Pol II and Pol IV in HNE induced mutagenesis, Pol II or Pol IV were expressed together with Pol V. This resulted in decrease of mutation frequency, suggesting that both enzymes can compete with Pol V, and bypass HNE-DNA adducts in an error-free manner. However, HNE-DNA adducts were easily bypassed by Pol IV and only infrequently by Pol II. Mutation spectrum established for strains expressing only Pol V, showed that in uvrA{sup -} bacteria the frequency of base substitutions and recombination increased in relation to NER proficient strains, particularly mutations at adenine sites. Among base substitutions A:T {yields} C:G, A:T {yields} G:C, G:C {yields} A:T and G:C {yields} T:A prevailed. The results suggest that Pol V can infrequently bypass HNE-DNA adducts inducing mutations at G, C and A sites, while bypass by Pol IV and Pol II is error-free, but for Pol II infrequent.

  7. RNA polymerase II transcriptional fidelity control and its functional interplay with DNA modifications

    Science.gov (United States)

    Xu, Liang; Wang, Wei; Chong, Jenny; Shin, Ji Hyun; Xu, Jun; Wang, Dong

    2016-01-01

    Accurate genetic information transfer is essential for life. As a key enzyme involved in the first step of gene expression, RNA polymerase II (Pol II) must maintain high transcriptional fidelity while it reads along DNA template and synthesizes RNA transcript in a stepwise manner during transcription elongation. DNA lesions or modifications may lead to significant changes in transcriptional fidelity or transcription elongation dynamics. In this review, we will summarize recent progress towards understanding the molecular basis of RNA Pol II transcriptional fidelity control and impacts of DNA lesions and modifications on Pol II transcription elongation. PMID:26392149

  8. Defect of Fe-S cluster binding by DNA polymerase δ in yeast suppresses UV-induced mutagenesis, but enhances DNA polymerase ζ - dependent spontaneous mutagenesis.

    Science.gov (United States)

    Stepchenkova, E I; Tarakhovskaya, E R; Siebler, H M; Pavlov, Y I

    2017-01-01

    Eukaryotic genomes are duplicated by a complex machinery, utilizing high fidelity replicative B-family DNA polymerases (pols) α, δ and ε. Specialized error-prone pol ζ, the fourth B-family member, is recruited when DNA synthesis by the accurate trio is impeded by replication stress or DNA damage. The damage tolerance mechanism dependent on pol ζ prevents DNA/genome instability and cell death at the expense of increased mutation rates. The pol switches occurring during this specialized replication are not fully understood. The loss of pol ζ results in the absence of induced mutagenesis and suppression of spontaneous mutagenesis. Disruption of the Fe-S cluster motif that abolish the interaction of the C-terminal domain (CTD) of the catalytic subunit of pol ζ with its accessory subunits, which are shared with pol δ, leads to a similar defect in induced mutagenesis. Intriguingly, the pol3-13 mutation that affects the Fe-S cluster in the CTD of the catalytic subunit of pol δ also leads to defective induced mutagenesis, suggesting the possibility that Fe-S clusters are essential for the pol switches during replication of damaged DNA. We confirmed that yeast strains with the pol3-13 mutation are UV-sensitive and defective in UV-induced mutagenesis. However, they have increased spontaneous mutation rates. We found that this increase is dependent on functional pol ζ. In the pol3-13 mutant strain with defective pol δ, there is a sharp increase in transversions and complex mutations, which require functional pol ζ, and an increase in the occurrence of large deletions, whose size is controlled by pol ζ. Therefore, the pol3-13 mutation abrogates pol ζ-dependent induced mutagenesis, but allows for pol ζ recruitment for the generation of spontaneous mutations and prevention of larger deletions. These results reveal differential control of the two major types of pol ζ-dependent mutagenesis by the Fe-S cluster present in replicative pol δ. Copyright © 2016

  9. Significant contribution of the 3′→5′ exonuclease activity to the high fidelity of nucleotide incorporation catalyzed by human DNA polymerase ϵ

    Science.gov (United States)

    Zahurancik, Walter J.; Klein, Seth J.; Suo, Zucai

    2014-01-01

    Most eukaryotic DNA replication is performed by A- and B-family DNA polymerases which possess a faithful polymerase activity that preferentially incorporates correct over incorrect nucleotides. Additionally, many replicative polymerases have an efficient 3′→5′ exonuclease activity that excises misincorporated nucleotides. Together, these activities contribute to overall low polymerase error frequency (one error per 106–108 incorporations) and support faithful eukaryotic genome replication. Eukaryotic DNA polymerase ϵ (Polϵ) is one of three main replicative DNA polymerases for nuclear genomic replication and is responsible for leading strand synthesis. Here, we employed pre-steady-state kinetic methods and determined the overall fidelity of human Polϵ (hPolϵ) by measuring the individual contributions of its polymerase and 3′→5′ exonuclease activities. The polymerase activity of hPolϵ has a high base substitution fidelity (10−4–10−7) resulting from large decreases in both nucleotide incorporation rate constants and ground-state binding affinities for incorrect relative to correct nucleotides. The 3′→5′ exonuclease activity of hPolϵ further enhances polymerization fidelity by an unprecedented 3.5 × 102 to 1.2 × 104-fold. The resulting overall fidelity of hPolϵ (10−6–10−11) justifies hPolϵ to be a primary enzyme to replicate human nuclear genome (0.1–1.0 error per round). Consistently, somatic mutations in hPolϵ, which decrease its exonuclease activity, are connected with mutator phenotypes and cancer formation. PMID:25414327

  10. Modulation of trinucleotide repeat instability by DNA polymerase β polymorphic variant R137Q.

    Directory of Open Access Journals (Sweden)

    Yaou Ren

    Full Text Available Trinucleotide repeat (TNR instability is associated with human neurodegenerative diseases and cancer. Recent studies have pointed out that DNA base excision repair (BER mediated by DNA polymerase β (pol β plays a crucial role in governing somatic TNR instability in a damage-location dependent manner. It has been shown that the activities and function of BER enzymes and cofactors can be modulated by their polymorphic variations. This could alter the function of BER in regulating TNR instability. However, the roles of BER polymorphism in modulating TNR instability remain to be elucidated. A previous study has shown that a pol β polymorphic variant, polβR137Q is associated with cancer due to its impaired polymerase activity and its deficiency in interacting with a BER cofactor, proliferating cell nuclear antigen (PCNA. In this study, we have studied the effect of the pol βR137Q variant on TNR instability. We showed that pol βR137Q exhibited weak DNA synthesis activity to cause TNR deletion during BER. We demonstrated that similar to wild-type pol β, the weak DNA synthesis activity of pol βR137Q allowed it to skip over a small loop formed on the template strand, thereby facilitating TNR deletion during BER. Our results further suggest that carriers with pol βR137Q polymorphic variant may not exhibit an elevated risk of developing human diseases that are associated with TNR instability.

  11. Altered Hematopoiesis in Mice Lacking DNA Polymerase μ Is Due to Inefficient Double-Strand Break Repair

    Science.gov (United States)

    Lucas, Daniel; Escudero, Beatriz; Ligos, José Manuel; Segovia, Jose Carlos; Estrada, Juan Camilo; Terrados, Gloria; Blanco, Luis; Samper, Enrique; Bernad, Antonio

    2009-01-01

    Polymerase mu (Polμ) is an error-prone, DNA-directed DNA polymerase that participates in non-homologous end-joining (NHEJ) repair. In vivo, Polμ deficiency results in impaired Vκ-Jκ recombination and altered somatic hypermutation and centroblast development. In Polμ−/− mice, hematopoietic development was defective in several peripheral and bone marrow (BM) cell populations, with about a 40% decrease in BM cell number that affected several hematopoietic lineages. Hematopoietic progenitors were reduced both in number and in expansion potential. The observed phenotype correlates with a reduced efficiency in DNA double-strand break (DSB) repair in hematopoietic tissue. Whole-body γ-irradiation revealed that Polμ also plays a role in DSB repair in non-hematopoietic tissues. Our results show that Polμ function is required for physiological hematopoietic development with an important role in maintaining early progenitor cell homeostasis and genetic stability in hematopoietic and non-hematopoietic tissues. PMID:19229323

  12. Strand displacement by DNA polymerase III occurs through a tau-psi-chi link to single-stranded DNA-binding protein coating the lagging strand template.

    Science.gov (United States)

    Yuan, Quan; McHenry, Charles S

    2009-11-13

    In addition to the well characterized processive replication reaction catalyzed by the DNA polymerase III holoenzyme on single-stranded DNA templates, the enzyme possesses an intrinsic strand displacement activity on flapped templates. The strand displacement activity is distinguished from the single-stranded DNA-templated reaction by a high dependence upon single-stranded DNA binding protein and an inability of gamma-complex to support the reaction in the absence of tau. However, if gamma-complex is present to load beta(2), a truncated tau protein containing only domains III-V will suffice. This truncated protein is sufficient to bind both the alpha subunit of DNA polymerase (Pol) III and chipsi. This is reminiscent of the minimal requirements for Pol III to replicate short single-stranded DNA-binding protein (SSB)-coated templates where tau is only required to serve as a scaffold to hold Pol III and chi in the same complex (Glover, B., and McHenry, C. (1998) J. Biol. Chem. 273, 23476-23484). We propose a model in which strand displacement by DNA polymerase III holoenzyme depends upon a Pol III-tau-psi-chi-SSB binding network, where SSB is bound to the displaced strand, stabilizing the Pol III-template interaction. The same interaction network is probably important for stabilizing the leading strand polymerase interactions with authentic replication forks. The specificity constant (k(cat)/K(m)) for the strand displacement reaction is approximately 300-fold less favorable than reactions on single-stranded templates and proceeds with a slower rate (150 nucleotides/s) and only moderate processivity (approximately 300 nucleotides). PriA, the initiator of replication restart on collapsed or misassembled replication forks, blocks the strand displacement reaction, even if added to an ongoing reaction.

  13. CMG helicase and DNA polymerase ε form a functional 15-subunit holoenzyme for eukaryotic leading-strand DNA replication.

    Science.gov (United States)

    Langston, Lance D; Zhang, Dan; Yurieva, Olga; Georgescu, Roxana E; Finkelstein, Jeff; Yao, Nina Y; Indiani, Chiara; O'Donnell, Mike E

    2014-10-28

    DNA replication in eukaryotes is asymmetric, with separate DNA polymerases (Pol) dedicated to bulk synthesis of the leading and lagging strands. Pol α/primase initiates primers on both strands that are extended by Pol ε on the leading strand and by Pol δ on the lagging strand. The CMG (Cdc45-MCM-GINS) helicase surrounds the leading strand and is proposed to recruit Pol ε for leading-strand synthesis, but to date a direct interaction between CMG and Pol ε has not been demonstrated. While purifying CMG helicase overexpressed in yeast, we detected a functional complex between CMG and native Pol ε. Using pure CMG and Pol ε, we reconstituted a stable 15-subunit CMG-Pol ε complex and showed that it is a functional polymerase-helicase on a model replication fork in vitro. On its own, the Pol2 catalytic subunit of Pol ε is inefficient in CMG-dependent replication, but addition of the Dpb2 protein subunit of Pol ε, known to bind the Psf1 protein subunit of CMG, allows stable synthesis with CMG. Dpb2 does not affect Pol δ function with CMG, and thus we propose that the connection between Dpb2 and CMG helps to stabilize Pol ε on the leading strand as part of a 15-subunit leading-strand holoenzyme we refer to as CMGE. Direct binding between Pol ε and CMG provides an explanation for specific targeting of Pol ε to the leading strand and provides clear mechanistic evidence for how strand asymmetry is maintained in eukaryotes.

  14. A structural role for the PHP domain in E. coli DNA polymerase III.

    Science.gov (United States)

    Barros, Tiago; Guenther, Joel; Kelch, Brian; Anaya, Jordan; Prabhakar, Arjun; O'Donnell, Mike; Kuriyan, John; Lamers, Meindert H

    2013-05-14

    In addition to the core catalytic machinery, bacterial replicative DNA polymerases contain a Polymerase and Histidinol Phosphatase (PHP) domain whose function is not entirely understood. The PHP domains of some bacterial replicases are active metal-dependent nucleases that may play a role in proofreading. In E. coli DNA polymerase III, however, the PHP domain has lost several metal-coordinating residues and is likely to be catalytically inactive. Genomic searches show that the loss of metal-coordinating residues in polymerase PHP domains is likely to have coevolved with the presence of a separate proofreading exonuclease that works with the polymerase. Although the E. coli Pol III PHP domain has lost metal-coordinating residues, the structure of the domain has been conserved to a remarkable degree when compared to that of metal-binding PHP domains. This is demonstrated by our ability to restore metal binding with only three point mutations, as confirmed by the metal-bound crystal structure of this mutant determined at 2.9 Å resolution. We also show that Pol III, a large multi-domain protein, unfolds cooperatively and that mutations in the degenerate metal-binding site of the PHP domain decrease the overall stability of Pol III and reduce its activity. While the presence of a PHP domain in replicative bacterial polymerases is strictly conserved, its ability to coordinate metals and to perform proofreading exonuclease activity is not, suggesting additional non-enzymatic roles for the domain. Our results show that the PHP domain is a major structural element in Pol III and its integrity modulates both the stability and activity of the polymerase.

  15. DNA-binding determinants promoting NHEJ by human Polμ.

    Science.gov (United States)

    Martin, Maria Jose; Juarez, Raquel; Blanco, Luis

    2012-12-01

    Non-homologous end-joining (NHEJ), the preferred pathway to repair double-strand breaks (DSBs) in higher eukaryotes, relies on a collection of molecular tools to process the broken ends, including specific DNA polymerases. Among them, Polµ is unique as it can catalyze DNA synthesis upon connection of two non-complementary ends. Here, we demonstrate that this capacity is intrinsic to Polµ, not conferred by other NHEJ factors. To understand the molecular determinants of its specific function in NHEJ, the interaction of human Polµ with DNA has been directly visualized by electromobility shift assay and footprinting assays. Stable interaction with a DNA gap requires the presence of a recessive 5'-P, thus orienting the catalytic domain for primer and nucleotide binding. Accordingly, recognition of the 5'-P is crucial to align the two DNA substrates of the NHEJ reaction. Site-directed mutagenesis demonstrates the relevance of three specific residues (Lys(249), Arg(253) and Arg(416)) in stabilizing the primer strand during end synapsis, allowing a range of microhomology-induced distortions beneficial for NHEJ. Moreover, our results suggest that the Polµ BRCT domain, thought to be exclusively involved in interaction with NHEJ core factors, has a direct role in binding the DNA region neighbor to the 5'-P, thus boosting Polµ-mediated NHEJ reactions.

  16. Bypass of a 5',8-cyclopurine-2'-deoxynucleoside by DNA polymerase β during DNA replication and base excision repair leads to nucleotide misinsertions and DNA strand breaks.

    Science.gov (United States)

    Jiang, Zhongliang; Xu, Meng; Lai, Yanhao; Laverde, Eduardo E; Terzidis, Michael A; Masi, Annalisa; Chatgilialoglu, Chryssostomos; Liu, Yuan

    2015-09-01

    5',8-Cyclopurine-2'-deoxynucleosides including 5',8-cyclo-dA (cdA) and 5',8-cyclo-dG (cdG) are induced by hydroxyl radicals resulting from oxidative stress such as ionizing radiation. 5',8-cyclopurine-2'-deoxynucleoside lesions are repaired by nucleotide excision repair with low efficiency, thereby leading to their accumulation in the human genome and lesion bypass by DNA polymerases during DNA replication and base excision repair (BER). In this study, for the first time, we discovered that DNA polymerase β (pol β) efficiently bypassed a 5'R-cdA, but inefficiently bypassed a 5'S-cdA during DNA replication and BER. We found that cell extracts from pol β wild-type mouse embryonic fibroblasts exhibited significant DNA synthesis activity in bypassing a cdA lesion located in replication and BER intermediates. However, pol β knock-out cell extracts exhibited little DNA synthesis to bypass the lesion. This indicates that pol β plays an important role in bypassing a cdA lesion during DNA replication and BER. Furthermore, we demonstrated that pol β inserted both a correct and incorrect nucleotide to bypass a cdA at a low concentration. Nucleotide misinsertion was significantly stimulated by a high concentration of pol β, indicating a mutagenic effect induced by pol β lesion bypass synthesis of a 5',8-cyclopurine-2'-deoxynucleoside. Moreover, we found that bypass of a 5'S-cdA by pol β generated an intermediate that failed to be extended by pol β, resulting in accumulation of single-strand DNA breaks. Our study provides the first evidence that pol β plays an important role in bypassing a 5',8-cyclo-dA during DNA replication and repair, as well as new insight into mutagenic effects and genome instability resulting from pol β bypassing of a cdA lesion. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Mechanism of error-free DNA synthesis across N1-methyl-deoxyadenosine by human DNA polymerase

    Energy Technology Data Exchange (ETDEWEB)

    Jain, Rinku; Choudhury, Jayati Roy; Buku, Angeliki; Johnson, Robert E.; Prakash, Louise; Prakash, Satya; Aggarwal, Aneel K.

    2017-03-08

    N1-methyl-deoxyadenosine (1-MeA) is formed by methylation of deoxyadenosine at the N1 atom. 1-MeA presents a block to replicative DNA polymerases due to its inability to participate in Watson-Crick (W-C) base pairing. Here we determine how human DNA polymerase-ι (Polι) promotes error-free replication across 1-MeA. Steady state kinetic analyses indicate that Polι is ~100 fold more efficient in incorporating the correct nucleotide T versus the incorrect nucleotide C opposite 1-MeA. To understand the basis of this selectivity, we determined ternary structures of Polι bound to template 1-MeA and incoming dTTP or dCTP. In both structures, template 1-MeA rotates to the syn conformation but pairs differently with dTTP versus dCTP. Thus, whereas dTTP partakes in stable Hoogsteen base pairing with 1-MeA, dCTP fails to gain a “foothold” and is largely disordered. Together, our kinetic and structural studies show how Polι maintains discrimination between correct and incorrect incoming nucleotide opposite 1-MeA in preserving genome integrity.

  18. Assessing the contribution of the herpes simplex virus DNA polymerase to spontaneous mutations

    Directory of Open Access Journals (Sweden)

    Leary Jeffry J

    2002-05-01

    Full Text Available Abstract Background The thymidine kinase (tk mutagenesis assay is often utilized to determine the frequency of herpes simplex virus (HSV replication-mediated mutations. Using this assay, clinical and laboratory HSV-2 isolates were shown to have a 10- to 80-fold higher frequency of spontaneous mutations compared to HSV-1. Methods A panel of HSV-1 and HSV-2, along with polymerase-recombinant viruses expressing type 2 polymerase (Pol within a type 1 genome, were evaluated using the tk and non-HSV DNA mutagenesis assays to measure HSV replication-dependent errors and determine whether the higher mutation frequency of HSV-2 is a distinct property of type 2 polymerases. Results Although HSV-2 have mutation frequencies higher than HSV-1 in the tk assay, these errors are assay-specific. In fact, wild type HSV-1 and the antimutator HSV-1 PAAr5 exhibited a 2–4 fold higher frequency than HSV-2 in the non-HSV DNA mutatagenesis assay. Furthermore, regardless of assay, HSV-1 recombinants expressing HSV-2 Pol had error rates similar to HSV-1, whereas the high mutator virus, HSV-2 6757, consistently showed signficant errors. Additionally, plasmid DNA containing the HSV-2 tk gene, but not type 1 tk or LacZ DNA, was shown to form an anisomorphic DNA stucture. Conclusions This study suggests that the Pol is not solely responsible for the virus-type specific differences in mutation frequency. Accordingly, it is possible that (a mutations may be modulated by other viral polypeptides cooperating with Pol, and (b the localized secondary structure of the viral genome may partially account for the apparently enhanced error frequency of HSV-2.

  19. Atomic Structure and Nonhomologous End-Joining Function of the Polymerase Component of Bacterial DNA Ligase D

    Energy Technology Data Exchange (ETDEWEB)

    Zhu,H.; Nandakumar, J.; Aniukwu, J.; Wang, L.; Glickman, M.; Lima, C.; Shuman, S.

    2006-01-01

    DNA ligase D (LigD) is a large polyfunctional protein that participates in a recently discovered pathway of nonhomologous end-joining in bacteria. LigD consists of an ATP-dependent ligase domain fused to a polymerase domain (Pol) and a phosphoesterase module. The Pol activity is remarkable for its dependence on manganese, its ability to perform templated and nontemplated primer extension reactions, and its preference for adding ribonucleotides to blunt DNA ends. Here we report the 1.5- Angstroms crystal structure of the Pol domain of Pseudomonas LigD and its complexes with manganese and ATP-dATP substrates, which reveal a minimized polymerase with a two-metal mechanism and a fold similar to that of archaeal DNA primase. Mutational analysis highlights the functionally relevant atomic contacts in the active site. Although distinct nucleoside conformations and contacts for ATP versus dATP are observed in the cocrystals, the functional analysis suggests that the ATP-binding mode is the productive conformation for dNMP and rNMP incorporation. We find that a mutation of Mycobacterium LigD that uniquely ablates the polymerase activity results in increased fidelity of blunt-end double-strand break repair in vivo by virtue of eliminating nucleotide insertions at the recombination junctions. Thus, LigD Pol is a direct catalyst of mutagenic nonhomologous end-joining in vivo. Our studies underscore a previously uncharacterized role for the primase-like polymerase family in DNA repair.

  20. Replicative DNA polymerase δ but not ε proofreads errors in Cis and in Trans.

    Directory of Open Access Journals (Sweden)

    Carrie L Flood

    2015-03-01

    Full Text Available It is now well established that in yeast, and likely most eukaryotic organisms, initial DNA replication of the leading strand is by DNA polymerase ε and of the lagging strand by DNA polymerase δ. However, the role of Pol δ in replication of the leading strand is uncertain. In this work, we use a reporter system in Saccharomyces cerevisiae to measure mutation rates at specific base pairs in order to determine the effect of heterozygous or homozygous proofreading-defective mutants of either Pol ε or Pol δ in diploid strains. We find that wild-type Pol ε molecules cannot proofread errors created by proofreading-defective Pol ε molecules, whereas Pol δ can not only proofread errors created by proofreading-defective Pol δ molecules, but can also proofread errors created by Pol ε-defective molecules. These results suggest that any interruption in DNA synthesis on the leading strand is likely to result in completion by Pol δ and also explain the higher mutation rates observed in Pol δ-proofreading mutants compared to Pol ε-proofreading defective mutants. For strains reverting via AT→GC, TA→GC, CG→AT, and GC→AT mutations, we find in addition a strong effect of gene orientation on mutation rate in proofreading-defective strains and demonstrate that much of this orientation dependence is due to differential efficiencies of mispair elongation. We also find that a 3'-terminal 8 oxoG, unlike a 3'-terminal G, is efficiently extended opposite an A and is not subject to proofreading. Proofreading mutations have been shown to result in tumor formation in both mice and humans; the results presented here can help explain the properties exhibited by those proofreading mutants.

  1. Role of DNA polymerase I in liquid holding recovery of uv-irradiated Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Tang, M S; Patrick, M H [Texas Univ., Dallas (USA)

    1977-09-01

    Excision of cyclobutyl dipyrimidines from, and accumulation of strand interruptions in DNA of different strains of E.coli K12 were determined during liquid holding recovery after uv irradiation. The extent of Pyr <> Pyr excision was the same (20 to 25%) for both a polA mutant (E.coli P3478) and its parental wild type strain (E.coli W3110); however, single strand interruptions accumulated during liquid holding of polA cells, but not in the parental strain. In contrast, excision was greatly reduced in a mutant (KMBL 1789) which is defective in the 5' ..-->.. 3' exonucleolytic function of DNA polymerase I. These data suggest that excision and resynthesis during liquid holding are carried out primarily, if not entirely, by DNA polymerase I. It is further concluded that excision alone is both a necessary and sufficient condition to elicit liquid holding recovery, and that this excision requires a functional polymerase I 5' ..-->.. 3' exonuclease.

  2. Proliferating cell nuclear antigen binds DNA polymerase-β and mediates 1-methyl-4-phenylpyridinium-induced neuronal death.

    Directory of Open Access Journals (Sweden)

    Zhentao Zhang

    Full Text Available The mechanisms leading to dopaminergic neuronal loss in the substantia nigra of patients with Parkinson disease (PD remain poorly understood. We recently reported that aberrant DNA replication mediated by DNA polymerase-β (DNA pol-β plays a causal role in the death of postmitotic neurons in an in vitro model of PD. In the present study, we show that both proliferating cell nuclear antigen (PCNA and DNA pol-β are required for MPP(+-induced neuronal death. PCNA binds to the catalytic domain of DNA pol-β in MPP(+-treated neurons and in post-mortem brain tissues of PD patients. The PCNA-DNA pol-β complex is loaded into DNA replication forks and mediates DNA replication in postmitotic neurons. The aberrant DNA replication mediated by the PCNA-DNA pol-β complex induces p53-dependent neuronal cell death. Our results indicate that the interaction of PCNA and DNA pol-β contributes to neuronal death in PD.

  3. Translesion synthesis DNA polymerases promote error-free replication through the minor-groove DNA adduct 3-deaza-3-methyladenine.

    Science.gov (United States)

    Yoon, Jung-Hoon; Roy Choudhury, Jayati; Park, Jeseong; Prakash, Satya; Prakash, Louise

    2017-11-10

    N3-Methyladenine (3-MeA) is formed in DNA by reaction with S -adenosylmethionine, the reactive methyl donor, and by reaction with alkylating agents. 3-MeA protrudes into the DNA minor groove and strongly blocks synthesis by replicative DNA polymerases (Pols). However, the mechanisms for replicating through this lesion in human cells remain unidentified. Here we analyzed the roles of translesion synthesis (TLS) Pols in the replication of 3-MeA-damaged DNA in human cells. Because 3-MeA has a short half-life in vitro , we used the stable 3-deaza analog, 3-deaza-3-methyladenine (3-dMeA), which blocks the DNA minor groove similarly to 3-MeA. We found that replication through the 3-dMeA adduct is mediated via three different pathways, dependent upon Polι/Polκ, Polθ, and Polζ. As inferred from biochemical studies, in the Polι/Polκ pathway, Polι inserts a nucleotide (nt) opposite 3-dMeA and Polκ extends synthesis from the inserted nt. In the Polθ pathway, Polθ carries out both the insertion and extension steps of TLS opposite 3-dMeA, and in the Polζ pathway, Polζ extends synthesis following nt insertion by an as yet unidentified Pol. Steady-state kinetic analyses indicated that Polι and Polθ insert the correct nt T opposite 3-dMeA with a much reduced catalytic efficiency and that both Pols exhibit a high propensity for inserting a wrong nt opposite this adduct. However, despite their low fidelity of synthesis opposite 3-dMeA, TLS opposite this lesion replicates DNA in a highly error-free manner in human cells. We discuss the implications of these observations for TLS mechanisms in human cells. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  4. Interaction between DNA Polymerase β and BRCA1.

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    Aya Masaoka

    Full Text Available The breast cancer 1 (BRCA1 protein is a tumor suppressor playing roles in DNA repair and cell cycle regulation. Studies of DNA repair functions of BRCA1 have focused on double-strand break (DSB repair pathways and have recently included base excision repair (BER. However, the function of BRCA1 in BER is not well defined. Here, we examined a BRCA1 role in BER, first in relation to alkylating agent (MMS treatment of cells and the BER enzyme DNA polymerase β (pol β. MMS treatment of BRCA1 negative human ovarian and chicken DT40 cells revealed hypersensitivity, and the combined gene deletion of BRCA1 and pol β in DT40 cells was consistent with these factors acting in the same repair pathway, possibly BER. Using cell extracts and purified proteins, BRCA1 and pol β were found to interact in immunoprecipitation assays, yet in vivo and in vitro assays for a BER role of BRCA1 were negative. An alternate approach with the human cells of immunofluorescence imaging and laser-induced DNA damage revealed negligible BRCA1 recruitment during the first 60 s after irradiation, the period typical of recruitment of pol β and other BER factors. Instead, 15 min after irradiation, BRCA1 recruitment was strong and there was γ-H2AX co-localization, consistent with DSBs and repair. The rapid recruitment of pol β was similar in BRCA1 positive and negative cells. However, a fraction of pol β initially recruited remained associated with damage sites much longer in BRCA1 positive than negative cells. Interestingly, pol β expression was required for BRCA1 recruitment, suggesting a partnership between these repair factors in DSB repair.

  5. Study of the activity of DNA polymerases β and λ using 5-formyluridine containing DNA substrates

    Directory of Open Access Journals (Sweden)

    Lavrik O. I.

    2012-06-01

    Full Text Available Aim. To investigate the TLS-activity of human DNA polymerases β and λ (pols β and λ using 5-formyluridine (5-foU containing DNA duplexes which are imitating the intermediates during replication of the leading DNA strand, and to study the influence of replication factors hRPA and hPCNA on this activity. Methods. The EMSA and the methods of enzyme’s kinetics were used. Results. The capability of pols β and λ to catalyze DNA synthesis across 5-foU was investigated and the kinetic characteristics of this process in the presence and in the absence of protein factors hRPA and hPCNA were evaluated. Conclusions. It was shown that: (i both proteins are able to catalyze TLS on used DNA substrates regardless of the reaction conditions, however, pol λ was more accurate enzyme; (ii hRPA can stimulate the efficacy of the nonmutagenic TLS catalyzed by pol at the nucleotide incorporation directly opposite of 5-foU, at the same time it doesn’t influence the incorporation efficacy if the damage displaced into the duplex; (iii hPCNA doesn’t influence the efficacy of TLS catalyzed by both enzymes.

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    Full Text Available Pol.Myo.10.RNA_polymerase_III.AllCell hg19 RNA polymerase RNA polymerase III Muscle... http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Myo.10.RNA_polymerase_III.AllCell.bed ...

  7. File list: Pol.Brs.20.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Brs.20.RNA_polymerase_III.AllCell hg19 RNA polymerase RNA polymerase III Breast... http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Brs.20.RNA_polymerase_III.AllCell.bed ...

  8. File list: Pol.Brs.05.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Brs.05.RNA_polymerase_III.AllCell hg19 RNA polymerase RNA polymerase III Breast... http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Brs.05.RNA_polymerase_III.AllCell.bed ...

  9. File list: Pol.Plc.05.RNA_polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Plc.05.RNA_polymerase_II.AllCell hg19 RNA polymerase RNA polymerase II Placenta... http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Plc.05.RNA_polymerase_II.AllCell.bed ...

  10. File list: Pol.Unc.20.RNA_polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  11. File list: Pol.Oth.50.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Oth.50.RNA_polymerase_III.AllCell hg19 RNA polymerase RNA polymerase III Others... http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Oth.50.RNA_polymerase_III.AllCell.bed ...

  12. File list: Pol.Brs.10.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Brs.10.RNA_polymerase_III.AllCell hg19 RNA polymerase RNA polymerase III Breast... http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Brs.10.RNA_polymerase_III.AllCell.bed ...

  13. File list: Pol.Liv.05.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Liv.05.RNA_polymerase_III.AllCell hg19 RNA polymerase RNA polymerase III Liver ...http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Liv.05.RNA_polymerase_III.AllCell.bed ...

  14. File list: Pol.Myo.05.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Myo.05.RNA_polymerase_III.AllCell hg19 RNA polymerase RNA polymerase III Muscle... http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Myo.05.RNA_polymerase_III.AllCell.bed ...

  15. File list: Pol.Oth.20.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Oth.20.RNA_polymerase_III.AllCell hg19 RNA polymerase RNA polymerase III Others... http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Oth.20.RNA_polymerase_III.AllCell.bed ...

  16. File list: Pol.Lar.10.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Lar.10.RNA_polymerase_III.AllCell ce10 RNA polymerase RNA polymerase III Larvae... http://dbarchive.biosciencedbc.jp/kyushu-u/ce10/assembled/Pol.Lar.10.RNA_polymerase_III.AllCell.bed ...

  17. File list: Pol.Liv.50.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Liv.50.RNA_polymerase_III.AllCell hg19 RNA polymerase RNA polymerase III Liver ...http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Liv.50.RNA_polymerase_III.AllCell.bed ...

  18. File list: Pol.Gon.10.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Gon.10.RNA_polymerase_III.AllCell hg19 RNA polymerase RNA polymerase III Gonad ...http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Gon.10.RNA_polymerase_III.AllCell.bed ...

  19. File list: Pol.Emb.50.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Emb.50.RNA_polymerase_III.AllCell ce10 RNA polymerase RNA polymerase III Embryo... http://dbarchive.biosciencedbc.jp/kyushu-u/ce10/assembled/Pol.Emb.50.RNA_polymerase_III.AllCell.bed ...

  20. File list: Pol.Oth.05.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Oth.05.RNA_polymerase_III.AllCell hg19 RNA polymerase RNA polymerase III Others... http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Oth.05.RNA_polymerase_III.AllCell.bed ...

  1. File list: Pol.Gon.20.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Gon.20.RNA_polymerase_III.AllCell hg19 RNA polymerase RNA polymerase III Gonad ...http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Gon.20.RNA_polymerase_III.AllCell.bed ...

  2. File list: Pol.Emb.05.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Emb.05.RNA_polymerase_III.AllCell ce10 RNA polymerase RNA polymerase III Embryo... http://dbarchive.biosciencedbc.jp/kyushu-u/ce10/assembled/Pol.Emb.05.RNA_polymerase_III.AllCell.bed ...

  3. File list: Pol.Myo.50.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Myo.50.RNA_polymerase_III.AllCell hg19 RNA polymerase RNA polymerase III Muscle... http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Myo.50.RNA_polymerase_III.AllCell.bed ...

  4. File list: Pol.Plc.20.RNA_polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Plc.20.RNA_polymerase_II.AllCell hg19 RNA polymerase RNA polymerase II Placenta... http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Plc.20.RNA_polymerase_II.AllCell.bed ...

  5. File list: Pol.Lar.05.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Lar.05.RNA_polymerase_III.AllCell ce10 RNA polymerase RNA polymerase III Larvae... http://dbarchive.biosciencedbc.jp/kyushu-u/ce10/assembled/Pol.Lar.05.RNA_polymerase_III.AllCell.bed ...

  6. File list: Pol.Oth.10.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Oth.10.RNA_polymerase_III.AllCell hg19 RNA polymerase RNA polymerase III Others... http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Oth.10.RNA_polymerase_III.AllCell.bed ...

  7. File list: Pol.Unc.10.RNA_polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Unc.10.RNA_polymerase_II.AllCell ce10 RNA polymerase RNA polymerase II Unclassi...p://dbarchive.biosciencedbc.jp/kyushu-u/ce10/assembled/Pol.Unc.10.RNA_polymerase_II.AllCell.bed ...

  8. File list: Pol.Unc.05.RNA_polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Unc.05.RNA_polymerase_II.AllCell ce10 RNA polymerase RNA polymerase II Unclassi...p://dbarchive.biosciencedbc.jp/kyushu-u/ce10/assembled/Pol.Unc.05.RNA_polymerase_II.AllCell.bed ...

  9. File list: Pol.Emb.20.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Emb.20.RNA_polymerase_III.AllCell ce10 RNA polymerase RNA polymerase III Embryo... http://dbarchive.biosciencedbc.jp/kyushu-u/ce10/assembled/Pol.Emb.20.RNA_polymerase_III.AllCell.bed ...

  10. File list: Pol.Neu.05.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Neu.05.RNA_polymerase_III.AllCell hg19 RNA polymerase RNA polymerase III Neural... http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Neu.05.RNA_polymerase_III.AllCell.bed ...

  11. File list: Pol.Myo.20.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Myo.20.RNA_polymerase_III.AllCell hg19 RNA polymerase RNA polymerase III Muscle... http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Myo.20.RNA_polymerase_III.AllCell.bed ...

  12. File list: Pol.Liv.20.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Liv.20.RNA_polymerase_III.AllCell hg19 RNA polymerase RNA polymerase III Liver ...http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Liv.20.RNA_polymerase_III.AllCell.bed ...

  13. File list: Pol.Gon.50.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Gon.50.RNA_polymerase_III.AllCell hg19 RNA polymerase RNA polymerase III Gonad ...http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Gon.50.RNA_polymerase_III.AllCell.bed ...

  14. File list: Pol.Lar.05.RNA_Polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Lar.05.RNA_Polymerase_II.AllCell ce10 RNA polymerase RNA Polymerase II Larvae h...ttp://dbarchive.biosciencedbc.jp/kyushu-u/ce10/assembled/Pol.Lar.05.RNA_Polymerase_II.AllCell.bed ...

  15. File list: Pol.Bld.20.RNA_Polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Bld.20.RNA_Polymerase_II.AllCell mm9 RNA polymerase RNA Polymerase II Blood SRX...tp://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Pol.Bld.20.RNA_Polymerase_II.AllCell.bed ...

  16. File list: Pol.Bld.20.RNA_Polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Bld.20.RNA_Polymerase_III.AllCell mm9 RNA polymerase RNA Polymerase III Blood h...ttp://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Pol.Bld.20.RNA_Polymerase_III.AllCell.bed ...

  17. File list: Pol.Plc.50.RNA_Polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Plc.50.RNA_Polymerase_III.AllCell mm9 RNA polymerase RNA Polymerase III Placent...a http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Pol.Plc.50.RNA_Polymerase_III.AllCell.bed ...

  18. File list: Pol.CDV.20.RNA_Polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.CDV.20.RNA_Polymerase_III.AllCell mm9 RNA polymerase RNA Polymerase III Cardiov...ascular http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Pol.CDV.20.RNA_Polymerase_III.AllCell.bed ...

  19. File list: Pol.Adp.20.RNA_Polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Adp.20.RNA_Polymerase_III.AllCell mm9 RNA polymerase RNA Polymerase III Adipocy...te http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Pol.Adp.20.RNA_Polymerase_III.AllCell.bed ...

  20. File list: Pol.Gon.20.RNA_polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Gon.20.RNA_polymerase_II.AllCell hg19 RNA polymerase RNA polymerase II Gonad ht...tp://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Gon.20.RNA_polymerase_II.AllCell.bed ...

  1. File list: Pol.Unc.05.RNA_Polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Unc.05.RNA_Polymerase_II.AllCell ce10 RNA polymerase RNA Polymerase II Unclassi...fied http://dbarchive.biosciencedbc.jp/kyushu-u/ce10/assembled/Pol.Unc.05.RNA_Polymerase_II.AllCell.bed ...

  2. File list: Pol.Unc.05.RNA_polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Unc.05.RNA_polymerase_II.AllCell hg19 RNA polymerase RNA polymerase II Unclassi...fied http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Unc.05.RNA_polymerase_II.AllCell.bed ...

  3. File list: Pol.Pan.05.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Pan.05.RNA_polymerase_III.AllCell hg19 RNA polymerase RNA polymerase III Pancre...as http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Pan.05.RNA_polymerase_III.AllCell.bed ...

  4. File list: Pol.CDV.05.RNA_Polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.CDV.05.RNA_Polymerase_III.AllCell mm9 RNA polymerase RNA Polymerase III Cardiov...ascular http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Pol.CDV.05.RNA_Polymerase_III.AllCell.bed ...

  5. File list: Pol.Unc.10.RNA_Polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Unc.10.RNA_Polymerase_II.AllCell ce10 RNA polymerase RNA Polymerase II Unclassi...fied http://dbarchive.biosciencedbc.jp/kyushu-u/ce10/assembled/Pol.Unc.10.RNA_Polymerase_II.AllCell.bed ...

  6. File list: Pol.Unc.10.RNA_Polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Unc.10.RNA_Polymerase_III.AllCell mm9 RNA polymerase RNA Polymerase III Unclass...ified http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Pol.Unc.10.RNA_Polymerase_III.AllCell.bed ...

  7. File list: Pol.Unc.50.RNA_Polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Unc.50.RNA_Polymerase_III.AllCell mm9 RNA polymerase RNA Polymerase III Unclass...ified http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Pol.Unc.50.RNA_Polymerase_III.AllCell.bed ...

  8. File list: Pol.Bld.50.RNA_Polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Bld.50.RNA_Polymerase_II.AllCell mm9 RNA polymerase RNA Polymerase II Blood SRX...tp://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Pol.Bld.50.RNA_Polymerase_II.AllCell.bed ...

  9. File list: Pol.Emb.50.RNA_Polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Emb.50.RNA_Polymerase_II.AllCell ce10 RNA polymerase RNA Polymerase II Embryo h...ttp://dbarchive.biosciencedbc.jp/kyushu-u/ce10/assembled/Pol.Emb.50.RNA_Polymerase_II.AllCell.bed ...

  10. File list: Pol.CDV.10.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.CDV.10.RNA_polymerase_III.AllCell hg19 RNA polymerase RNA polymerase III Cardio...vascular http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.CDV.10.RNA_polymerase_III.AllCell.bed ...

  11. File list: Pol.Unc.50.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Unc.50.RNA_polymerase_III.AllCell hg19 RNA polymerase RNA polymerase III Unclas...sified http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Unc.50.RNA_polymerase_III.AllCell.bed ...

  12. File list: Pol.Plc.20.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Plc.20.RNA_polymerase_III.AllCell hg19 RNA polymerase RNA polymerase III Placen...ta http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Plc.20.RNA_polymerase_III.AllCell.bed ...

  13. File list: Pol.Bon.20.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Bon.20.RNA_polymerase_III.AllCell hg19 RNA polymerase RNA polymerase III Bone h...ttp://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Bon.20.RNA_polymerase_III.AllCell.bed ...

  14. File list: Pol.Gon.50.RNA_polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Gon.50.RNA_polymerase_II.AllCell hg19 RNA polymerase RNA polymerase II Gonad ht...tp://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Gon.50.RNA_polymerase_II.AllCell.bed ...

  15. File list: Pol.Pan.10.RNA_Polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Pan.10.RNA_Polymerase_III.AllCell mm9 RNA polymerase RNA Polymerase III Pancrea...s http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Pol.Pan.10.RNA_Polymerase_III.AllCell.bed ...

  16. File list: Pol.Bon.05.RNA_Polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Bon.05.RNA_Polymerase_III.AllCell mm9 RNA polymerase RNA Polymerase III Bone ht...tp://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Pol.Bon.05.RNA_Polymerase_III.AllCell.bed ...

  17. File list: Pol.Adp.20.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Adp.20.RNA_polymerase_III.AllCell hg19 RNA polymerase RNA polymerase III Adipoc...yte http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Adp.20.RNA_polymerase_III.AllCell.bed ...

  18. File list: Pol.Adp.10.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Adp.10.RNA_polymerase_III.AllCell hg19 RNA polymerase RNA polymerase III Adipoc...yte http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Adp.10.RNA_polymerase_III.AllCell.bed ...

  19. File list: Pol.Plc.10.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Plc.10.RNA_polymerase_III.AllCell hg19 RNA polymerase RNA polymerase III Placen...ta http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Plc.10.RNA_polymerase_III.AllCell.bed ...

  20. File list: Pol.Prs.10.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Prs.10.RNA_polymerase_III.AllCell hg19 RNA polymerase RNA polymerase III Prosta...te http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Prs.10.RNA_polymerase_III.AllCell.bed ...

  1. File list: Pol.CDV.05.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.CDV.05.RNA_polymerase_III.AllCell hg19 RNA polymerase RNA polymerase III Cardio...vascular http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.CDV.05.RNA_polymerase_III.AllCell.bed ...

  2. File list: Pol.Lng.10.RNA_polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Lng.10.RNA_polymerase_II.AllCell hg19 RNA polymerase RNA polymerase II Lung SRX... http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Lng.10.RNA_polymerase_II.AllCell.bed ...

  3. File list: Pol.Unc.20.RNA_polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Unc.20.RNA_polymerase_II.AllCell hg19 RNA polymerase RNA polymerase II Unclassi...fied http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Unc.20.RNA_polymerase_II.AllCell.bed ...

  4. File list: Pol.Plc.05.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Plc.05.RNA_polymerase_III.AllCell hg19 RNA polymerase RNA polymerase III Placen...ta http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Plc.05.RNA_polymerase_III.AllCell.bed ...

  5. File list: Pol.Myo.50.RNA_polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Myo.50.RNA_polymerase_II.AllCell hg19 RNA polymerase RNA polymerase II Muscle h...ttp://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Myo.50.RNA_polymerase_II.AllCell.bed ...

  6. File list: Pol.Myo.10.RNA_polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Myo.10.RNA_polymerase_II.AllCell hg19 RNA polymerase RNA polymerase II Muscle h...ttp://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Myo.10.RNA_polymerase_II.AllCell.bed ...

  7. File list: Pol.Myo.05.RNA_polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Myo.05.RNA_polymerase_II.AllCell hg19 RNA polymerase RNA polymerase II Muscle h...ttp://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Myo.05.RNA_polymerase_II.AllCell.bed ...

  8. File list: Pol.Bon.05.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Bon.05.RNA_polymerase_III.AllCell hg19 RNA polymerase RNA polymerase III Bone h...ttp://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Bon.05.RNA_polymerase_III.AllCell.bed ...

  9. File list: Pol.Unc.20.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Unc.20.RNA_polymerase_III.AllCell ce10 RNA polymerase RNA polymerase III Unclas...sified http://dbarchive.biosciencedbc.jp/kyushu-u/ce10/assembled/Pol.Unc.20.RNA_polymerase_III.AllCell.bed ...

  10. File list: Pol.Plc.50.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Plc.50.RNA_polymerase_III.AllCell hg19 RNA polymerase RNA polymerase III Placen...ta http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Plc.50.RNA_polymerase_III.AllCell.bed ...

  11. File list: Pol.Myo.20.RNA_polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Myo.20.RNA_polymerase_II.AllCell hg19 RNA polymerase RNA polymerase II Muscle h...ttp://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Myo.20.RNA_polymerase_II.AllCell.bed ...

  12. File list: Pol.Bon.50.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Bon.50.RNA_polymerase_III.AllCell hg19 RNA polymerase RNA polymerase III Bone h...ttp://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Bon.50.RNA_polymerase_III.AllCell.bed ...

  13. File list: Pol.Unc.10.RNA_polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Unc.10.RNA_polymerase_II.AllCell hg19 RNA polymerase RNA polymerase II Unclassi...fied http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Unc.10.RNA_polymerase_II.AllCell.bed ...

  14. File list: Pol.CDV.50.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

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    Lifescience Database Archive (English)

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    Lifescience Database Archive (English)

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    Lifescience Database Archive (English)

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  15. File list: Pol.Emb.10.RNA_polymerase_II.AllCell [Chip-atlas[Archive

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  13. File list: Pol.Epd.50.RNA_polymerase_III.AllCell [Chip-atlas[Archive

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  14. File list: Pol.Unc.50.RNA_polymerase_II.AllCell [Chip-atlas[Archive

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  15. Analysis of UV-induced mutation spectra in Escherichia coli by DNA polymerase {eta} from Arabidopsis thaliana

    Energy Technology Data Exchange (ETDEWEB)

    Santiago, Maria Jesus [Departamento de Genetica, Facultad de Ciencias, Edificio Gregor Mendel, Campus Rabanales, Universidad de Cordoba (Spain); Alejandre-Duran, Encarna [Departamento de Genetica, Facultad de Ciencias, Edificio Gregor Mendel, Campus Rabanales, Universidad de Cordoba (Spain); Ruiz-Rubio, Manuel [Departamento de Genetica, Facultad de Ciencias, Edificio Gregor Mendel, Campus Rabanales, Universidad de Cordoba (Spain)]. E-mail: ge1rurum@uco.es

    2006-10-10

    DNA polymerase {eta} belongs to the Y-family of DNA polymerases, enzymes that are able to synthesize past template lesions that block replication fork progression. This polymerase accurately bypasses UV-associated cis-syn cyclobutane thymine dimers in vitro and therefore may contributes to resistance against sunlight in vivo, both ameliorating survival and decreasing the level of mutagenesis. We cloned and sequenced a cDNA from Arabidopsis thaliana which encodes a protein containing several sequence motifs characteristics of Pol{eta} homologues, including a highly conserved sequence reported to be present in the active site of the Y-family DNA polymerases. The gene, named AtPOLH, contains 14 exons and 13 introns and is expressed in different plant tissues. A strain from Saccharomyces cerevisiae, deficient in Pol{eta} activity, was transformed with a yeast expression plasmid containing the AtPOLH cDNA. The rate of survival to UV irradiation in the transformed mutant increased to similar values of the wild type yeast strain, showing that AtPOLH encodes a functional protein. In addition, when AtPOLH is expressed in Escherichia coli, a change in the mutational spectra is detected when bacteria are irradiated with UV light. This observation might indicate that AtPOLH could compete with DNA polymerase V and then bypass cyclobutane pyrimidine dimers incorporating two adenylates.

  16. High sensitive RNA detection by one-step RT-PCR using the genetically engineered variant of DNA polymerase with reverse transcriptase activity from hyperthermophilies.

    Science.gov (United States)

    Okano, Hiroyuki; Baba, Misato; Kawato, Katsuhiro; Hidese, Ryota; Yanagihara, Itaru; Kojima, Kenji; Takita, Teisuke; Fujiwara, Shinsuke; Yasukawa, Kiyoshi

    2018-03-01

    One-step RT-PCR has not been widely used even though some thermostable DNA polymerases with reverse transcriptase (RT) activity were developed from bacterial and archaeal polymerases, which is owing to low cDNA synthesis activity from RNA. In the present study, we developed highly-sensitive one-step RT-PCR using the single variant of family A DNA polymerase with RT activity, K4pol L329A (L329A), from the hyperthermophilic bacterium Thermotoga petrophila K4 or the 16-tuple variant of family B DNA polymerase with RT activity, RTX, from the hyperthermophilic archaeon Thermococcus kodakarensis. Optimization of reaction condition revealed that the activities for cDNA synthesis and PCR of K4pol L329A and RTX were highly affected by the concentrations of MgCl 2 and Mn(OCOCH 3 ) 2 as well as those of K4pol L329A or RTX. Under the optimized condition, 300 copies/μl of target RNA in 10 μl reaction volumes were successfully detected by the one-step RT-PCR with K4pol L329A or RTX, which was almost equally sensitive enough compared with the current RT-PCR condition using retroviral RT and thermostable DNA polymerase. Considering that K4pol L329A and RTX are stable even at 90-100°C, our results suggest that the one-step RT-PCR with K4pol L329A or RTX is more advantageous than the current one. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  17. The role of DNA polymerase I in liquid holding recovery of UV-irradiated Escherichia coli

    International Nuclear Information System (INIS)

    Tang, M.-S.; Patrick, M.H.

    1977-01-01

    Excision of cyclobutyl dipyrimidines from, and accumulation of strand interruptions in, DNA of different strains of E.coli K12 were determined during liquid holding recovery after UV irradiation. The extent of Pyr Pyr excision was the same (20 to 25%) for both a polA mutant (E.coli P3478) and its parental wild type strain (E.coli W3110); however, single strand interruptions accumulated during liquid holding of polA cells, but not in the parental strain. In contrast, excision was greatly reduced in a mutant (KMBL 1789) which is defective in the 5' → 3' exonucleolytic function of DNA polymerase I. These data suggest that excision and resynthesis during liquid holding are carried out primarily, if not entirely, by DNA polymerase I. It is further concluded that excision alone is both a necessary and sufficient condition to elicit liquid holding recovery, and that this excision requires a functional polymerase I 5' → 3' exonuclease. (author)

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  13. File list: Pol.Prs.10.RNA_polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  14. File list: Pol.Prs.05.RNA_polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  15. File list: Pol.ALL.20.RNA_polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  16. File list: Pol.ALL.10.RNA_polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  17. File list: Pol.Epd.05.RNA_polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  18. File list: Pol.PSC.05.RNA_polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  19. File list: Pol.Prs.20.RNA_polymerase_II.AllCell [Chip-atlas[Archive

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  20. File list: Pol.ALL.50.RNA_polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  1. File list: Pol.Utr.05.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  2. File list: Pol.Adl.50.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  3. File list: Pol.ALL.10.RNA_polymerase_II.AllCell [Chip-atlas[Archive

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  4. The Roles of Family B and D DNA Polymerases in Thermococcus Species 9°N Okazaki Fragment Maturation*

    Science.gov (United States)

    Greenough, Lucia; Kelman, Zvi; Gardner, Andrew F.

    2015-01-01

    During replication, Okazaki fragment maturation is a fundamental process that joins discontinuously synthesized DNA fragments into a contiguous lagging strand. Efficient maturation prevents repeat sequence expansions, small duplications, and generation of double-stranded DNA breaks. To address the components required for the process in Thermococcus, Okazaki fragment maturation was reconstituted in vitro using purified proteins from Thermococcus species 9°N or cell extracts. A dual color fluorescence assay was developed to monitor reaction substrates, intermediates, and products. DNA polymerase D (polD) was proposed to function as the replicative polymerase in Thermococcus replicating both the leading and the lagging strands. It is shown here, however, that it stops before the previous Okazaki fragments, failing to rapidly process them. Instead, Family B DNA polymerase (polB) was observed to rapidly fill the gaps left by polD and displaces the downstream Okazaki fragment to create a flap structure. This flap structure was cleaved by flap endonuclease 1 (Fen1) and the resultant nick was ligated by DNA ligase to form a mature lagging strand. The similarities to both bacterial and eukaryotic systems and evolutionary implications of archaeal Okazaki fragment maturation are discussed. PMID:25814667

  5. File list: Pol.CDV.10.RNA_polymerase_II.AllCell [Chip-atlas[Archive

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  6. File list: Pol.Lng.10.RNA_Polymerase_II.AllCell [Chip-atlas[Archive

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  7. File list: Pol.Adl.05.RNA_polymerase_III.AllCell [Chip-atlas[Archive

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  8. File list: Pol.Spl.10.RNA_Polymerase_II.AllCell [Chip-atlas[Archive

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  9. File list: Pol.Lng.05.RNA_polymerase_III.AllCell [Chip-atlas[Archive

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  10. File list: Pol.Lng.05.RNA_Polymerase_II.AllCell [Chip-atlas[Archive

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  11. File list: Pol.Lng.20.RNA_Polymerase_II.AllCell [Chip-atlas[Archive

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  12. File list: Pol.Spl.05.RNA_Polymerase_II.AllCell [Chip-atlas[Archive

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  13. File list: Pol.Emb.50.RNA_polymerase_II.AllCell [Chip-atlas[Archive

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  15. File list: Pol.Lng.20.RNA_polymerase_III.AllCell [Chip-atlas[Archive

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  16. File list: Pol.Lng.50.RNA_polymerase_III.AllCell [Chip-atlas[Archive

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  17. File list: Pol.Adl.10.RNA_polymerase_III.AllCell [Chip-atlas[Archive

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  18. File list: Pol.Emb.10.RNA_polymerase_II.AllCell [Chip-atlas[Archive

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  19. File list: Pol.CDV.20.RNA_polymerase_II.AllCell [Chip-atlas[Archive

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  20. File list: Pol.Neu.20.RNA_polymerase_II.AllCell [Chip-atlas[Archive

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  1. File list: Pol.CDV.20.RNA_Polymerase_II.AllCell [Chip-atlas[Archive

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  2. File list: Pol.Adp.50.RNA_polymerase_II.AllCell [Chip-atlas[Archive

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  3. File list: Pol.Adl.50.RNA_polymerase_II.AllCell [Chip-atlas[Archive

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  4. File list: Pol.Adl.20.RNA_polymerase_II.AllCell [Chip-atlas[Archive

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  5. File list: Pol.Neu.50.RNA_polymerase_II.AllCell [Chip-atlas[Archive

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  6. File list: Pol.Neu.05.RNA_polymerase_II.AllCell [Chip-atlas[Archive

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  7. File list: Pol.ALL.05.RNA_polymerase_III.AllCell [Chip-atlas[Archive

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  8. File list: Pol.ALL.20.RNA_polymerase_III.AllCell [Chip-atlas[Archive

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  9. File list: Pol.Bld.50.RNA_polymerase_III.AllCell [Chip-atlas[Archive

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  11. File list: Pol.Bld.20.RNA_polymerase_III.AllCell [Chip-atlas[Archive

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  12. File list: Pol.Utr.05.RNA_polymerase_II.AllCell [Chip-atlas[Archive

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  13. File list: Pol.ALL.10.RNA_polymerase_II.AllCell [Chip-atlas[Archive

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  14. File list: Pol.Utr.50.RNA_polymerase_II.AllCell [Chip-atlas[Archive

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  15. Human PrimPol activity is enhanced by RPA.

    Science.gov (United States)

    Martínez-Jiménez, María I; Lahera, Antonio; Blanco, Luis

    2017-04-10

    Human PrimPol is a primase belonging to the AEP superfamily with the unique ability to synthesize DNA primers de novo, and a non-processive DNA polymerase able to bypass certain DNA lesions. PrimPol facilitates both mitochondrial and nuclear replication fork progression either acting as a conventional TLS polymerase, or repriming downstream of blocking lesions. In vivo assays have shown that PrimPol is rapidly recruited to sites of DNA damage by interaction with the human replication protein A (RPA). In agreement with previous findings, we show here that the higher affinity of RPA for ssDNA inhibits PrimPol activities in short ssDNA templates. In contrast, once the amount of ssDNA increases up to a length in which both proteins can simultaneously bind ssDNA, as expected during replicative stress conditions, PrimPol and RPA functionally interact, and their binding capacities are mutually enhanced. When using M13 ssDNA as template, RPA stimulated both the primase and polymerase activities of PrimPol, either alone or in synergy with Polε. These new findings supports the existence of a functional PrimPol/RPA association that allows repriming at the exposed ssDNA regions formed in the leading strand upon replicase stalling.

  16. The Translesion Polymerase Pol η Is Required for Efficient Epstein-Barr Virus Infectivity and Is Regulated by the Viral Deubiquitinating Enzyme BPLF1.

    Science.gov (United States)

    Dyson, Ossie F; Pagano, Joseph S; Whitehurst, Christopher B

    2017-10-01

    Epstein-Barr virus (EBV) infection and lytic replication are known to induce a cellular DNA damage response. We previously showed that the virally encoded BPLF1 protein interacts with and regulates several members of the translesion synthesis (TLS) pathway, a DNA damage tolerance pathway, and that these cellular factors enhance viral infectivity. BPLF1 is a late lytic cycle gene, but the protein is also packaged in the viral tegument, indicating that BPLF1 may function both early and late during infection. The BPLF1 protein expresses deubiquitinating activity that is strictly conserved across the Herpesviridae ; mutation of the active site cysteine results in a loss of enzymatic activity. Infection with an EBV BPLF1 knockout virus results in decreased EBV infectivity. Polymerase eta (Pol η), a specialized DNA repair polymerase, functions in TLS and allows for DNA replication complexes to bypass lesions in DNA. Here we report that BPLF1 interacts with Pol η and that Pol η protein levels are increased in the presence of functional BPLF1. BPLF1 promotes a nuclear relocalization of Pol η molecules which are focus-like in appearance, consistent with the localization observed when Pol η is recruited to sites of DNA damage. Knockdown of Pol η resulted in decreased production of infectious virus, and further, Pol η was found to bind to EBV DNA, suggesting that it may allow for bypass of damaged viral DNA during its replication. The results suggest a mechanism by which EBV recruits cellular repair factors, such as Pol η, to sites of viral DNA damage via BPLF1, thereby allowing for efficient viral DNA replication. IMPORTANCE Epstein-Barr virus is the causative agent of infectious mononucleosis and infects approximately 90% of the world's population. It causes lymphomas in individuals with acquired and innate immune disorders and is strongly associated with Hodgkin's lymphoma, Burkitt's lymphoma, diffuse large B-cell lymphomas, nasopharyngeal carcinoma (NPC), and

  17. File list: Pol.Oth.20.RNA_polymerase_II.AllCell [Chip-atlas[Archive

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  18. File list: Pol.Adp.50.RNA_Polymerase_II.AllCell [Chip-atlas[Archive

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  19. File list: Pol.Kid.20.RNA_polymerase_II.AllCell [Chip-atlas[Archive

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  20. File list: Pol.Kid.10.RNA_polymerase_II.AllCell [Chip-atlas[Archive

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  1. File list: Pol.Oth.50.RNA_polymerase_II.AllCell [Chip-atlas[Archive

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  2. File list: Pol.Bld.50.RNA_polymerase_II.AllCell [Chip-atlas[Archive

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  4. File list: Pol.Bld.10.RNA_polymerase_II.AllCell [Chip-atlas[Archive

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  5. File list: Pol.Kid.50.RNA_polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  6. File list: Pol.Oth.05.RNA_polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Oth.05.RNA_polymerase_II.AllCell hg19 RNA polymerase RNA polymerase II Others S...RX1027435,SRX668218,SRX1027436,SRX1027434,SRX1027433,SRX099879,SRX099880 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.Oth.05.RNA_polymerase_II.AllCell.bed ...

  7. Mammalian α-polymerase: cloning of partial complementary DNA and immunobinding of catalytic subunit in crude homogenate protein blots

    International Nuclear Information System (INIS)

    SenGupta, D.N.; Kumar, P.; Zmudzka, B.Z.; Coughlin, S.; Vishwanatha, J.K.; Robey, F.A.; Parrott, C.; Wilson, S.H.

    1987-01-01

    A new polyclonal antibody against the α-polymerase catalytic polypeptide was prepared by using homogeneous HeLa cellα-polymerase. The antibody neutralized α-polymerase activity and was strong and specific for the α-polymerase catalytic polypeptide (M/sub r/ 183,000) in Western blot analysis of crude extracts of HeLa cells. The antibody was used to screen a cDNA library of newborn rat brain poly(A+) RNA in λgt11. A positive phage was identified and plaque purified. This phage, designated λpolα1.2, also was found to be positive with an antibody against Drosophila α-polymerase. The insert in λpolα1.2 (1183 base pairs) contained a poly(A) sequence at the 3' terminus and a short in-phase open reading frame at the 5' terminus. A synthetic oligopeptide (eight amino acids) corresponding to the open reading frame was used to raise antiserum in rabbits. Antibody affinity purified from this serum was found to be immunoreactive against purified α-polymerase by enzyme-linked immunosorbent assay and was capable of immunoprecipitating α-polymerase. This indicated the λpolα1.2 insert encoded an α-polymerase epitope and suggested that the cDNA corresponded to an α-polymerase mRNA. This was confirmed in hybrid selection experiments using pUC9 containing the cDNA insert and poly(A+) RNA from newborn rat brain; the insert hybridized to mRNA capable of encoding α-polymerase catalytic polypeptides. Northern blot analysis of rat brain poly(A+) RNA revealed that this mRNA is ∼5.4 kilobases

  8. File list: Pol.EmF.05.RNA_Polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.EmF.05.RNA_Polymerase_II.AllCell mm9 RNA polymerase RNA Polymerase II Embryonic...RX143288 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Pol.EmF.05.RNA_Polymerase_II.AllCell.bed ...

  9. File list: Pol.NoD.50.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  10. File list: Pol.NoD.50.RNA_polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  11. File list: Pol.NoD.05.RNA_polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  12. File list: Pol.NoD.10.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  13. File list: Pol.NoD.10.RNA_polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  14. File list: Pol.NoD.20.RNA_polymerase_III.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.NoD.20.RNA_polymerase_III.AllCell hg19 RNA polymerase RNA polymerase III No des...cription http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Pol.NoD.20.RNA_polymerase_III.AllCell.bed ...

  15. File list: Pol.NoD.20.RNA_polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  16. File list: Pol.YSt.10.RNA_Polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  17. File list: Pol.Lar.05.RNA_polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  18. File list: Pol.Oth.05.RNA_Polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  19. File list: Pol.Lar.20.RNA_polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Lar.20.RNA_polymerase_II.AllCell dm3 RNA polymerase RNA polymerase II Larvae SR...SRX661503,SRX026742,SRX013070,SRX013072,SRX182775,SRX151961,SRX013082,SRX013113 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Pol.Lar.20.RNA_polymerase_II.AllCell.bed ...

  20. Gastrointestinal hyperplasia with altered expression of DNA polymerase beta.

    Directory of Open Access Journals (Sweden)

    Katsuhiko Yoshizawa

    2009-08-01

    Full Text Available Altered expression of DNA polymerase beta (Pol beta has been documented in a large percentage of human tumors. However, tumor prevalence or predisposition resulting from Pol beta over-expression has not yet been evaluated in a mouse model.We have recently developed a novel transgenic mouse model that over-expresses Pol beta. These mice present with an elevated incidence of spontaneous histologic lesions, including cataracts, hyperplasia of Brunner's gland and mucosal hyperplasia in the duodenum. In addition, osteogenic tumors in mice tails, such as osteoma and osteosarcoma were detected. This is the first report of elevated tumor incidence in a mouse model of Pol beta over-expression. These findings prompted an evaluation of human gastrointestinal tumors with regard to Pol beta expression. We observed elevated expression of Pol beta in stomach adenomas and thyroid follicular carcinomas, but reduced Pol beta expression in esophageal adenocarcinomas and squamous carcinomas.These data support the hypothesis that balanced and proficient base excision repair protein expression and base excision repair capacity is required for genome stability and protection from hyperplasia and tumor formation.

  1. The roles of family B and D DNA polymerases in Thermococcus species 9°N Okazaki fragment maturation.

    Science.gov (United States)

    Greenough, Lucia; Kelman, Zvi; Gardner, Andrew F

    2015-05-15

    During replication, Okazaki fragment maturation is a fundamental process that joins discontinuously synthesized DNA fragments into a contiguous lagging strand. Efficient maturation prevents repeat sequence expansions, small duplications, and generation of double-stranded DNA breaks. To address the components required for the process in Thermococcus, Okazaki fragment maturation was reconstituted in vitro using purified proteins from Thermococcus species 9°N or cell extracts. A dual color fluorescence assay was developed to monitor reaction substrates, intermediates, and products. DNA polymerase D (polD) was proposed to function as the replicative polymerase in Thermococcus replicating both the leading and the lagging strands. It is shown here, however, that it stops before the previous Okazaki fragments, failing to rapidly process them. Instead, Family B DNA polymerase (polB) was observed to rapidly fill the gaps left by polD and displaces the downstream Okazaki fragment to create a flap structure. This flap structure was cleaved by flap endonuclease 1 (Fen1) and the resultant nick was ligated by DNA ligase to form a mature lagging strand. The similarities to both bacterial and eukaryotic systems and evolutionary implications of archaeal Okazaki fragment maturation are discussed. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  2. Eukaryotic DNA Replicases

    KAUST Repository

    Zaher, Manal S.; Oke, Muse; Hamdan, Samir

    2014-01-01

    The current model of the eukaryotic DNA replication fork includes three replicative DNA polymerases, polymerase α/primase complex (Pol α), polymerase δ (Pol δ), and polymerase ε (Pol ε). The primase synthesizes 8–12 nucleotide RNA primers that are extended by the DNA polymerization activity of Pol α into 30–35 nucleotide RNA-DNA primers. Replication factor C (RFC) opens the polymerase clamp-like processivity factor, proliferating cell nuclear antigen (PCNA), and loads it onto the primer-template. Pol δ utilizes PCNA to mediate highly processive DNA synthesis, while Pol ε has intrinsic high processivity that is modestly stimulated by PCNA. Pol ε replicates the leading strand and Pol δ replicates the lagging strand in a division of labor that is not strict. The three polymerases are comprised of multiple subunits and share unifying features in their large catalytic and B subunits. The remaining subunits are evolutionarily not related and perform diverse functions. The catalytic subunits are members of family B, which are distinguished by their larger sizes due to inserts in their N- and C-terminal regions. The sizes of these inserts vary among the three polymerases, and their functions remain largely unknown. Strikingly, the quaternary structures of Pol α, Pol δ, and Pol ε are arranged similarly. The catalytic subunits adopt a globular structure that is linked via its conserved C-terminal region to the B subunit. The remaining subunits are linked to the catalytic and B subunits in a highly flexible manner.

  3. Eukaryotic DNA Replicases

    KAUST Repository

    Zaher, Manal S.

    2014-11-21

    The current model of the eukaryotic DNA replication fork includes three replicative DNA polymerases, polymerase α/primase complex (Pol α), polymerase δ (Pol δ), and polymerase ε (Pol ε). The primase synthesizes 8–12 nucleotide RNA primers that are extended by the DNA polymerization activity of Pol α into 30–35 nucleotide RNA-DNA primers. Replication factor C (RFC) opens the polymerase clamp-like processivity factor, proliferating cell nuclear antigen (PCNA), and loads it onto the primer-template. Pol δ utilizes PCNA to mediate highly processive DNA synthesis, while Pol ε has intrinsic high processivity that is modestly stimulated by PCNA. Pol ε replicates the leading strand and Pol δ replicates the lagging strand in a division of labor that is not strict. The three polymerases are comprised of multiple subunits and share unifying features in their large catalytic and B subunits. The remaining subunits are evolutionarily not related and perform diverse functions. The catalytic subunits are members of family B, which are distinguished by their larger sizes due to inserts in their N- and C-terminal regions. The sizes of these inserts vary among the three polymerases, and their functions remain largely unknown. Strikingly, the quaternary structures of Pol α, Pol δ, and Pol ε are arranged similarly. The catalytic subunits adopt a globular structure that is linked via its conserved C-terminal region to the B subunit. The remaining subunits are linked to the catalytic and B subunits in a highly flexible manner.

  4. File list: Pol.NoD.10.RNA_polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  5. File list: Pol.NoD.05.RNA_Polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  6. File list: Pol.NoD.10.RNA_Polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  7. File list: Pol.NoD.20.RNA_polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  8. File list: Pol.NoD.50.RNA_polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.NoD.50.RNA_polymerase_II.AllCell sacCer3 RNA polymerase RNA polymerase II No de...scription http://dbarchive.biosciencedbc.jp/kyushu-u/sacCer3/assembled/Pol.NoD.50.RNA_polymerase_II.AllCell.bed ...

  9. Editing of misaligned 3'-termini by an intrinsic 3'-5' exonuclease activity residing in the PHP domain of a family X DNA polymerase.

    Science.gov (United States)

    Baños, Benito; Lázaro, José M; Villar, Laurentino; Salas, Margarita; de Vega, Miguel

    2008-10-01

    Bacillus subtilis gene yshC encodes a family X DNA polymerase (PolX(Bs)), whose biochemical features suggest that it plays a role during DNA repair processes. Here, we show that, in addition to the polymerization activity, PolX(Bs) possesses an intrinsic 3'-5' exonuclease activity specialized in resecting unannealed 3'-termini in a gapped DNA substrate. Biochemical analysis of a PolX(Bs) deletion mutant lacking the C-terminal polymerase histidinol phosphatase (PHP) domain, present in most of the bacterial/archaeal PolXs, as well as of this separately expressed protein region, allow us to state that the 3'-5' exonuclease activity of PolX(Bs) resides in its PHP domain. Furthermore, site-directed mutagenesis of PolX(Bs) His339 and His341 residues, evolutionary conserved in the PHP superfamily members, demonstrated that the predicted metal binding site is directly involved in catalysis of the exonucleolytic reaction. The implications of the unannealed 3'-termini resection by the 3'-5' exonuclease activity of PolX(Bs) in the DNA repair context are discussed.

  10. DNA polymerase-beta is expressed early in neurons of Alzheimer's disease brain and is loaded into DNA replication forks in neurons challenged with beta-amyloid

    NARCIS (Netherlands)

    Copani, Agata; Hoozemans, Jeroen J. M.; Caraci, Filippo; Calafiore, Marco; van Haastert, Elise S.; Veerhuis, Robert; Rozemuller, Annemieke J. M.; Aronica, Eleonora; Sortino, Maria Angela; Nicoletti, Ferdinando

    2006-01-01

    Cultured neurons exposed to synthetic beta-amyloid (Abeta) fragments reenter the cell cycle and initiate a pathway of DNA replication that involves the repair enzyme DNA polymerase-beta (DNA pol-beta) before undergoing apoptotic death. In this study, by performing coimmunoprecipitation experiments

  11. Variants of sequence family B Thermococcus kodakaraensis DNA polymerase with increased mismatch extension selectivity.

    Directory of Open Access Journals (Sweden)

    Claudia Huber

    Full Text Available Fidelity and selectivity of DNA polymerases are critical determinants for the biology of life, as well as important tools for biotechnological applications. DNA polymerases catalyze the formation of DNA strands by adding deoxynucleotides to a primer, which is complementarily bound to a template. To ensure the integrity of the genome, DNA polymerases select the correct nucleotide and further extend the nascent DNA strand. Thus, DNA polymerase fidelity is pivotal for ensuring that cells can replicate their genome with minimal error. DNA polymerases are, however, further optimized for more specific biotechnological or diagnostic applications. Here we report on the semi-rational design of mutant libraries derived by saturation mutagenesis at single sites of a 3'-5'-exonuclease deficient variant of Thermococcus kodakaraensis DNA polymerase (KOD pol and the discovery for variants with enhanced mismatch extension selectivity by screening. Sites of potential interest for saturation mutagenesis were selected by their proximity to primer or template strands. The resulting libraries were screened via quantitative real-time PCR. We identified three variants with single amino acid exchanges-R501C, R606Q, and R606W-which exhibited increased mismatch extension selectivity. These variants were further characterized towards their potential in mismatch discrimination. Additionally, the identified enzymes were also able to differentiate between cytosine and 5-methylcytosine. Our results demonstrate the potential in characterizing and developing DNA polymerases for specific PCR based applications in DNA biotechnology and diagnostics.

  12. SHH1, a homeodomain protein required for DNA methylation, as well as RDR2, RDM4, and chromatin remodeling factors, associate with RNA polymerase IV.

    Directory of Open Access Journals (Sweden)

    Julie A Law

    2011-07-01

    Full Text Available DNA methylation is an evolutionarily conserved epigenetic modification that is critical for gene silencing and the maintenance of genome integrity. In Arabidopsis thaliana, the de novo DNA methyltransferase, domains rearranged methyltransferase 2 (DRM2, is targeted to specific genomic loci by 24 nt small interfering RNAs (siRNAs through a pathway termed RNA-directed DNA methylation (RdDM. Biogenesis of the targeting siRNAs is thought to be initiated by the activity of the plant-specific RNA polymerase IV (Pol-IV. However, the mechanism through which Pol-IV is targeted to specific genomic loci and whether factors other than the core Pol-IV machinery are required for Pol-IV activity remain unknown. Through the affinity purification of nuclear RNA polymerase D1 (NRPD1, the largest subunit of the Pol-IV polymerase, we found that several previously identified RdDM components co-purify with Pol-IV, namely RNA-dependent RNA polymerase 2 (RDR2, CLASSY1 (CLSY1, and RNA-directed DNA methylation 4 (RDM4, suggesting that the upstream siRNA generating portion of the RdDM pathway may be more physically coupled than previously envisioned. A homeodomain protein, SAWADEE homeodomain homolog 1 (SHH1, was also found to co-purify with NRPD1; and we demonstrate that SHH1 is required for de novo and maintenance DNA methylation, as well as for the accumulation of siRNAs at specific loci, confirming it is a bonafide component of the RdDM pathway.

  13. WRNIP1 functions upstream of DNA polymerase η in the UV-induced DNA damage response

    Energy Technology Data Exchange (ETDEWEB)

    Yoshimura, Akari, E-mail: akari_yo@stu.musashino-u.ac.jp [Molecular Cell Biology Laboratory, Research Institute of Pharmaceutical Sciences, Faculty of Pharmacy, Musashino University, 1-1-20 Shinmachi, Nishitokyo-shi, Tokyo 202-8585 (Japan); Kobayashi, Yume [Molecular Cell Biology Laboratory, Research Institute of Pharmaceutical Sciences, Faculty of Pharmacy, Musashino University, 1-1-20 Shinmachi, Nishitokyo-shi, Tokyo 202-8585 (Japan); Tada, Shusuke [Department of Medical Biochemistry, Faculty of Pharmaceutical Sciences, Toho University, 2-2-1 Miyama, Funabashi-shi, Chiba 274-8510 (Japan); Seki, Masayuki [Department of Biochemistry, Tohoku Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai-shi, Miyagi 981-8558 (Japan); Enomoto, Takemi [Molecular Cell Biology Laboratory, Research Institute of Pharmaceutical Sciences, Faculty of Pharmacy, Musashino University, 1-1-20 Shinmachi, Nishitokyo-shi, Tokyo 202-8585 (Japan)

    2014-09-12

    Highlights: • The UV sensitivity of POLH{sup −/−} cells was suppressed by disruption of WRNIP1. • In WRNIP1{sup −/−/−}/POLH{sup −/−} cells, mutation frequencies and SCE after irradiation reduced. • WRNIP1 defect recovered rate of fork progression after irradiation in POLH{sup −/−} cells. • WRNIP1 functions upstream of Polη in the translesion DNA synthesis pathway. - Abstract: WRNIP1 (WRN-interacting protein 1) was first identified as a factor that interacts with WRN, the protein that is defective in Werner syndrome (WS). WRNIP1 associates with DNA polymerase η (Polη), but the biological significance of this interaction remains unknown. In this study, we analyzed the functional interaction between WRNIP1 and Polη by generating knockouts of both genes in DT40 chicken cells. Disruption of WRNIP1 in Polη-disrupted (POLH{sup −/−}) cells suppressed the phenotypes associated with the loss of Polη: sensitivity to ultraviolet light (UV), delayed repair of cyclobutane pyrimidine dimers (CPD), elevated frequency of mutation, elevated levels of UV-induced sister chromatid exchange (SCE), and reduced rate of fork progression after UV irradiation. These results suggest that WRNIP1 functions upstream of Polη in the response to UV irradiation.

  14. File list: Pol.CeL.50.RNA_polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  15. File list: Pol.CeL.20.RNA_polymerase_II.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  16. DNA repair synthesis in human fibroblasts requires DNA polymerase delta

    International Nuclear Information System (INIS)

    Nishida, C.; Reinhard, P.; Linn, S.

    1988-01-01

    When UV-irradiated cultured diploid human fibroblasts were permeabilized with Brij-58 then separated from soluble material by centrifugation, conservative DNA repair synthesis could be restored by a soluble factor obtained from the supernatant of similarly treated HeLa cells. Extensive purification of this factor yielded a 10.2 S, 220,000-dalton polypeptide with the DNA polymerase and 3'- to 5'-exonuclease activities reported for DNA polymerase delta II. Monoclonal antibody to KB cell DNA polymerase alpha, while binding to HeLa DNA polymerase alpha, did not bind to the HeLa DNA polymerase delta. Moreover, at micromolar concentrations N2-(p-n-butylphenyl)-2'-deoxyguanosine 5'-triphosphate (BuPdGTP) and 2-(p-n-butylanilino)-2'-deoxyadenosine 5'-triphosphate (BuAdATP) were potent inhibitors of DNA polymerase alpha, but did not inhibit the DNA polymerase delta. Neither purified DNA polymerase alpha nor beta could promote repair DNA synthesis in the permeabilized cells. Furthermore, under conditions which inhibited purified DNA polymerase alpha by greater than 90%, neither monoclonal antibodies to DNA polymerase alpha, BuPdGTP, nor BuAdATP was able to inhibit significantly the DNA repair synthesis mediated by the DNA polymerase delta. Thus, it appears that a major portion of DNA repair synthesis induced by UV irradiation might be catalyzed by DNA polymerase delta. When xeroderma pigmentosum human diploid fibroblasts were utilized, DNA repair synthesis dependent upon ultraviolet light could be restored by addition of both T4 endonuclease V and DNA polymerase delta, but not by addition of either one alone

  17. Anti-tumor effects of dehydroaltenusin, a specific inhibitor of mammalian DNA polymerase α

    International Nuclear Information System (INIS)

    Maeda, Naoki; Kokai, Yasuo; Ohtani, Seiji; Sahara, Hiroeki; Kuriyama, Isoko; Kamisuki, Shinji; Takahashi, Shunya; Sakaguchi, Kengo; Sugawara, Fumio; Yoshida, Hiromi; Sato, Noriyuki; Mizushina, Yoshiyuki

    2007-01-01

    In the screening of selective inhibitors of eukaryotic DNA polymerases (pols), dehydroaltenusin was found to be an inhibitor of pol α from a fungus (Alternaria tennuis). We succeeded in chemically synthesizing dehydroaltenusin, and the compound inhibited only mammalian pol α with IC 50 value of 0.5 μM, and did not influence the activities of other replicative pols such as pols δ and ε, but also showed no effect on pol α activity from another vertebrate, fish, or from a plant species. Dehydroaltenusin also had no influence on the other pols and DNA metabolic enzymes tested. The compound also inhibited the proliferation of human cancer cells with LD 50 values of 38.0-44.4 μM. In an in vivo anti-tumor assay on nude mice bearing solid tumors of HeLa cells, dehydroaltenusin was shown to be a promising suppressor of solid tumors. Histopathological examination revealed that increased tumor necrosis and decreased mitotic index were apparently detected by the compound in vivo. Therefore, dehydroaltenusin could be of interest as not only a mammalian pol α-specific inhibitor, but also as a candidate drug for anti-cancer treatment

  18. Overexpressed DNA polymerase iota regulated by JNK/c-Jun contributes to hypermutagenesis in bladder cancer.

    Science.gov (United States)

    Yuan, Fang; Xu, Zhigang; Yang, Mingzhen; Wei, Quanfang; Zhang, Yi; Yu, Jin; Zhi, Yi; Liu, Yang; Chen, Zhiwen; Yang, Jin

    2013-01-01

    Human DNA polymerase iota (pol ι) possesses high error-prone DNA replication features and performs translesion DNA synthesis. It may be specialized and strictly regulated in normal mammalian cells. Dysregulation of pol ι may contribute to the acquisition of a mutator phenotype. However, there are few reports describing the transcription regulatory mechanism of pol ι, and there is controversy regarding its role in carcinogenesis. In this study, we performed the deletion and point-mutation experiment, EMSA, ChIP, RNA interference and western blot assay to prove that c-Jun activated by c-Jun N-terminal kinase (JNK) regulates the transcription of pol ι in normal and cancer cells. Xeroderma pigmentosum group C protein (XPC) and ataxia-telangiectasia mutated related protein (ATR) promote early JNK activation in response to DNA damage and consequently enhance the expression of pol ι, indicating that the novel role of JNK signal pathway is involved in DNA damage response. Furthermore, associated with elevated c-Jun activity, the overexpression of pol ι is positively correlated with the clinical tumor grade in 97 bladder cancer samples and may contribute to the hypermutagenesis. The overexpressed pol ι-involved mutagenesis is dependent on JNK/c-Jun pathway in bladder cancer cells identifying by the special mutation spectra. Our results support the conclusion that dysregulation of pol ι by JNK/c-Jun is involved in carcinogenesis and offer a novel understanding of the role of pol ι or c-Jun in mutagenesis.

  19. Structural basis for proficient incorporation of dTTP opposite O6-methylguanine by human DNA polymerase iota.

    Science.gov (United States)

    Pence, Matthew G; Choi, Jeong-Yun; Egli, Martin; Guengerich, F Peter

    2010-12-24

    O(6)-methylguanine (O(6)-methylG) is highly mutagenic and is commonly found in DNA exposed to methylating agents, even physiological ones (e.g. S-adenosylmethionine). The efficiency of a truncated, catalytic DNA polymerase ι core enzyme was determined for nucleoside triphosphate incorporation opposite O(6)-methylG, using steady-state kinetic analyses. The results presented here corroborate previous work from this laboratory using full-length pol ι, which showed that dTTP incorporation occurs with high efficiency opposite O(6)-methylG. Misincorporation of dTTP opposite O(6)-methylG occurred with ∼6-fold higher efficiency than incorporation of dCTP. Crystal structures of the truncated form of pol ι with O(6)-methylG as the template base and incoming dCTP or dTTP were solved and showed that O(6)-methylG is rotated into the syn conformation in the pol ι active site and that dTTP misincorporation by pol ι is the result of Hoogsteen base pairing with the adduct. Both dCTP and dTTP base paired with the Hoogsteen edge of O(6)-methylG. A single, short hydrogen bond formed between the N3 atom of dTTP and the N7 atom of O(6)-methylG. Protonation of the N3 atom of dCTP and bifurcation of the N3 hydrogen between the N7 and O(6) atoms of O(6)-methylG allow base pairing of the lesion with dCTP. We conclude that differences in the Hoogsteen hydrogen bonding between nucleotides is the main factor in the preferential selectivity of dTTP opposite O(6)-methylG by human pol ι, in contrast to the mispairing modes observed previously for O(6)-methylG in the structures of the model DNA polymerases Sulfolobus solfataricus Dpo4 and Bacillus stearothermophilus DNA polymerase I.

  20. Characterization of DNA polymerase β from Danio rerio by overexpression in E. coli using the in vivo/in vitro compatible pIVEX plasmid

    Directory of Open Access Journals (Sweden)

    Ishikawa Mitsuru

    2011-10-01

    Full Text Available Abstract Background Eukaryotic DNA polymerase β (pol β, the polymerase thought to be responsible for DNA repair synthesis, has been extensively characterized in rats and humans. However, pol β has not been purified or enzymatically characterized from the model fish species Danio rerio (zebrafish. We used the in vitro/in vivo dual expression system plasmid, pIVEX, to express Danio rerio pol β (Danio pol β for biochemical characterization. Results Danio pol β encoded by the in vitro/in vivo-compatible pIVEX plasmid was expressed in E. coli BL21(DE3, BL21(DE3pLysS, and KRX, and in vitro as a C-terminal His-tagged protein. Danio pol β expressed in vitro was subject to proteolysis; therefore, bacterial overexpression was used to produce the protein for kinetic analyses. KRX cells were preferred because of their reduced propensity for leaky expression of pol β. The cDNA of Danio rerio pol β encodes a protein of 337 amino acids, which is 2-3 amino acids longer than other pol β proteins, and contains a P63D amino acid substitution, unlike mammalian pol βs. This substitution lies in a hairpin sequence within an 8-kDa domain, likely to be important in DNA binding. We performed extensive biochemical characterization of Danio pol β in comparison with rat pol β, which revealed its sensitivity to metal ion activators (Mn2+ and Mg2+, its optimum salt concentration (10 mM KCl and 50 mM NaCl, alkaline pH optimum (pH 9.0, and low temperature optimum (30°C. Substituting Mn2+ for Mg2+ resulted in 8.6-fold higher catalytic efficiency (kcat/Km. Conclusions Our characterization of pol β from a model fish organism contributes to the study of the function and evolution of DNA polymerases, which are emerging as important cellular targets for chemical intervention in the development of anticancer agents.

  1. Role of polymerase η in mitochondrial mutagenesis of Saccharomyces cerevisiae

    Energy Technology Data Exchange (ETDEWEB)

    Chatterjee, Nimrat; Pabla, Ritu [Dept. of Cell Biology and Anatomy, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., Fort Worth, TX 76107 (United States); Siede, Wolfram, E-mail: wolfram.siede@unthsc.edu [Dept. of Cell Biology and Anatomy, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., Fort Worth, TX 76107 (United States)

    2013-02-08

    Highlights: ► DNA polymerase η is detectable in mitochondria of budding yeast. ► Pol η reduces UV-induced mitochondrial base pair substitutions and frameshifts. ► For UV-induced base pair substitutions, Pol η and Pol ζ interact epistatically. -- Abstract: DNA polymerase η mostly catalyzes an error-free bypass of the most frequent UV lesions, pyrimidine dimers of the cyclobutane-type. In addition to its nuclear localization, we show here for the first time its mitochondrial localization in budding yeast. In mitochondria, this polymerase improves bypass replication fidelity opposite UV damage as shown in base pair substitution and frameshift assays. For base pair substitutions, polymerase η appears to be related in function and epistatic to DNA polymerase ζ which, however, plays the opposite role in the nucleus.

  2. Effect of captan on the exonuclease activities of DNA polymerase I from E. coli and reverse transcriptase from avian myeloblastosis virus

    International Nuclear Information System (INIS)

    Freeman-Wittig, M.J.B.

    1986-01-01

    The DNA pol I polymerase activity is known to be inhibited by captan. When captan was tested for its ability to alter the exonuclease activity of DNA pol I, degradation was enhanced at high substrate concentrations. At low concentrations of DNA, captan was inhibitory. By assaying the two exonuclease activities separately it was shown that the differential effect by captan was the result of a combined inhibition of the 3' → 5' exonuclease and enhancement of the 5' → 3' exonuclease. Studies employing [ 14 C] captan showed that the alterations in DNA pol I activities were a result of the irreversible binding of captan to the enzyme in a ratio of 1:1. The effect of captan on AMV reverse transcriptase RNase H activity was also studied. RNase H activity appeared to be more sensitive to captan than was the polymerase activity. Inhibition of the polymerase activity could be prevented by deoxynucleotide triphosphate and was increased by templateprimer. RNase H activity, which showed a sigmoidal relationship between activity and substrate concentration, decreased in V/sub max/ with no change in the Hill coefficient in the presence of captan

  3. Roles of the active site residues and metal cofactors in noncanonical base-pairing during catalysis by human DNA polymerase iota.

    Science.gov (United States)

    Makarova, Alena V; Ignatov, Artem; Miropolskaya, Nataliya; Kulbachinskiy, Andrey

    2014-10-01

    Human DNA polymerase iota (Pol ι) is a Y-family polymerase that can bypass various DNA lesions but possesses very low fidelity of DNA synthesis in vitro. Structural analysis of Pol ι revealed a narrow active site that promotes noncanonical base-pairing during catalysis. To better understand the structure-function relationships in the active site of Pol ι we investigated substitutions of individual amino acid residues in its fingers domain that contact either the templating or the incoming nucleotide. Two of the substitutions, Y39A and Q59A, significantly decreased the catalytic activity but improved the fidelity of Pol ι. Surprisingly, in the presence of Mn(2+) ions, the wild-type and mutant Pol ι variants efficiently incorporated nucleotides opposite template purines containing modifications that disrupted either Hoogsteen or Watson-Crick base-pairing, suggesting that Pol ι may use various types of interactions during nucleotide addition. In contrast, in Mg(2+) reactions, wild-type Pol ι was dependent on Hoogsteen base-pairing, the Y39A mutant was essentially inactive, and the Q59A mutant promoted Watson-Crick interactions with template purines. The results suggest that Pol ι utilizes distinct mechanisms of nucleotide incorporation depending on the metal cofactor and reveal important roles of specific residues from the fingers domain in base-pairing and catalysis. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. DNA polymerase eta participates in the mutagenic bypass of adducts induced by benzo[a]pyrene diol epoxide in mammalian cells.

    Directory of Open Access Journals (Sweden)

    Alden C Klarer

    Full Text Available Y-family DNA-polymerases have larger active sites that can accommodate bulky DNA adducts allowing them to bypass these lesions during replication. One member, polymerase eta (pol eta, is specialized for the bypass of UV-induced thymidine-thymidine dimers, correctly inserting two adenines. Loss of pol eta function is the molecular basis for xeroderma pigmentosum (XP variant where the accumulation of mutations results in a dramatic increase in UV-induced skin cancers. Less is known about the role of pol eta in the bypass of other DNA adducts. A commonly encountered DNA adduct is that caused by benzo[a]pyrene diol epoxide (BPDE, the ultimate carcinogenic metabolite of the environmental chemical benzo[a]pyrene. Here, treatment of pol eta-deficient fibroblasts from humans and mice with BPDE resulted in a significant decrease in Hprt gene mutations. These studies in mammalian cells support a number of in vitro reports that purified pol eta has error-prone activity on plasmids with site-directed BPDE adducts. Sequencing the Hprt gene from this work shows that the majority of mutations are G>T transversions. These data suggest that pol eta has error-prone activity when bypassing BPDE-adducts. Understanding the basis of environmental carcinogen-derived mutations may enable prevention strategies to reduce such mutations with the intent to reduce the number of environmentally relevant cancers.

  5. The role of the PHP domain associated with DNA polymerase X from Thermus thermophilus HB8 in base excision repair.

    Science.gov (United States)

    Nakane, Shuhei; Nakagawa, Noriko; Kuramitsu, Seiki; Masui, Ryoji

    2012-11-01

    Base excision repair (BER) is one of the most commonly used DNA repair pathways involved in genome stability. X-family DNA polymerases (PolXs) play critical roles in BER, especially in filling single-nucleotide gaps. In addition to a polymerase core domain, bacterial PolXs have a polymerase and histidinol phosphatase (PHP) domain with phosphoesterase activity which is also required for BER. However, the role of the PHP domain of PolX in bacterial BER remains unresolved. We found that the PHP domain of Thermus thermophilus HB8 PolX (ttPolX) functions as two types of phosphoesterase in BER, including a 3'-phosphatase and an apurinic/apyrimidinic (AP) endonuclease. Experiments using T. thermophilus HB8 cell lysates revealed that the majority of the 3'-phosphatase and AP endonuclease activities are attributable to the another phosphoesterase in T. thermophilus HB8, endonuclease IV (ttEndoIV). However, ttPolX possesses significant 3'-phosphatase activity in ΔttendoIV cell lysate, indicating possible complementation. Our experiments also reveal that there are only two enzymes that display the 3'-phosphatase activity in the T. thermophilus HB8 cell, ttPolX and ttEndoIV. Furthermore, phenotypic analysis of ΔttpolX, ΔttendoIV, and ΔttpolX/ΔttendoIV using hydrogen peroxide and sodium nitrite supports the hypothesis that ttPolX functions as a backup for ttEndoIV in BER. Copyright © 2012 Elsevier B.V. All rights reserved.

  6. The Crystal Structure of PF-8, the DNA Polymerase Accessory Subunit from Kaposi's Sarcoma-Associated Herpesvirus

    Energy Technology Data Exchange (ETDEWEB)

    Baltz, Jennifer L.; Filman, David J.; Ciustea, Mihai; Silverman, Janice Elaine Y.; Lautenschlager, Catherine L.; Coen, Donald M.; Ricciardi, Robert P.; Hogle, James M.; (UPENN)

    2009-12-01

    Kaposi's sarcoma-associated herpesvirus is an emerging pathogen whose mechanism of replication is poorly understood. PF-8, the presumed processivity factor of Kaposi's sarcoma-associated herpesvirus DNA polymerase, acts in combination with the catalytic subunit, Pol-8, to synthesize viral DNA. We have solved the crystal structure of residues 1 to 304 of PF-8 at a resolution of 2.8 {angstrom}. This structure reveals that each monomer of PF-8 shares a fold common to processivity factors. Like human cytomegalovirus UL44, PF-8 forms a head-to-head dimer in the form of a C clamp, with its concave face containing a number of basic residues that are predicted to be important for DNA binding. However, there are several differences with related proteins, especially in loops that extend from each monomer into the center of the C clamp and in the loops that connect the two subdomains of each protein, which may be important for determining PF-8's mode of binding to DNA and to Pol-8. Using the crystal structures of PF-8, the herpes simplex virus catalytic subunit, and RB69 bacteriophage DNA polymerase in complex with DNA and initial experiments testing the effects of inhibition of PF-8-stimulated DNA synthesis by peptides derived from Pol-8, we suggest a model for how PF-8 might form a ternary complex with Pol-8 and DNA. The structure and the model suggest interesting similarities and differences in how PF-8 functions relative to structurally similar proteins.

  7. Archaeal RNA polymerase arrests transcription at DNA lesions.

    Science.gov (United States)

    Gehring, Alexandra M; Santangelo, Thomas J

    2017-01-01

    Transcription elongation is not uniform and transcription is often hindered by protein-bound factors or DNA lesions that limit translocation and impair catalysis. Despite the high degree of sequence and structural homology of the multi-subunit RNA polymerases (RNAP), substantial differences in response to DNA lesions have been reported. Archaea encode only a single RNAP with striking structural conservation with eukaryotic RNAP II (Pol II). Here, we demonstrate that the archaeal RNAP from Thermococcus kodakarensis is sensitive to a variety of DNA lesions that pause and arrest RNAP at or adjacent to the site of DNA damage. DNA damage only halts elongation when present in the template strand, and the damage often results in RNAP arresting such that the lesion would be encapsulated with the transcription elongation complex. The strand-specific halt to archaeal transcription elongation on modified templates is supportive of RNAP recognizing DNA damage and potentially initiating DNA repair through a process akin to the well-described transcription-coupled DNA repair (TCR) pathways in Bacteria and Eukarya.

  8. Transition-state destabilization reveals how human DNA polymerase β proceeds across the chemically unstable lesion N7-methylguanine

    Science.gov (United States)

    Ouzon-Shubeita, Hala; Lee, Seongmin

    2014-01-01

    N7-Methyl-2′-deoxyguanosine (m7dG) is the predominant lesion formed by methylating agents. A systematic investigation on the effect of m7dG on DNA replication has been difficult due to the chemical instability of m7dG. To gain insights into the m7dG effect, we employed a 2′-fluorine-mediated transition-state destabilzation strategy. Specifically, we determined kinetic parameters for dCTP insertion opposite a chemically stable m7dG analogue, 2′-fluoro-m7dG (Fm7dG), by human DNA polymerase β (polβ) and solved three X-ray structures of polβ in complex with the templating Fm7dG paired with incoming dCTP or dTTP analogues. The kinetic studies reveal that the templating Fm7dG slows polβ catalysis ∼300-fold, suggesting that m7dG in genomic DNA may impede replication by some DNA polymerases. The structural analysis reveals that Fm7dG forms a canonical Watson–Crick base pair with dCTP, but metal ion coordination is suboptimal for catalysis in the polβ-Fm7dG:dCTP complex, which partially explains the slow insertion of dCTP opposite Fm7dG by polβ. In addition, the polβ-Fm7dG:dTTP structure shows open protein conformations and staggered base pair conformations, indicating that N7-methylation of dG does not promote a promutagenic replication. Overall, the first systematic studies on the effect of m7dG on DNA replication reveal that polβ catalysis across m7dG is slow, yet highly accurate. PMID:24966350

  9. Editing of misaligned 3′-termini by an intrinsic 3′–5′ exonuclease activity residing in the PHP domain of a family X DNA polymerase

    Science.gov (United States)

    Baños, Benito; Lázaro, José M.; Villar, Laurentino; de Vega, Miguel

    2008-01-01

    Bacillus subtilis gene yshC encodes a family X DNA polymerase (PolXBs), whose biochemical features suggest that it plays a role during DNA repair processes. Here, we show that, in addition to the polymerization activity, PolXBs possesses an intrinsic 3′–5′ exonuclease activity specialized in resecting unannealed 3′-termini in a gapped DNA substrate. Biochemical analysis of a PolXBs deletion mutant lacking the C-terminal polymerase histidinol phosphatase (PHP) domain, present in most of the bacterial/archaeal PolXs, as well as of this separately expressed protein region, allow us to state that the 3′–5′ exonuclease activity of PolXBs resides in its PHP domain. Furthermore, site-directed mutagenesis of PolXBs His339 and His341 residues, evolutionary conserved in the PHP superfamily members, demonstrated that the predicted metal binding site is directly involved in catalysis of the exonucleolytic reaction. The implications of the unannealed 3′-termini resection by the 3′–5′ exonuclease activity of PolXBs in the DNA repair context are discussed. PMID:18776221

  10. Functional roles of DNA polymerases β and γ

    International Nuclear Information System (INIS)

    Huebscher, U.; Kuenzle, C.C.; Spadari, S.

    1979-01-01

    The physiological functions of DNA polymerases (deoxynucleosidetriphosphate:DNA deoxynucleotidyltransferase, EC2.7.7.7)β and γ were investigated by using neuronal nuclei and synaptosomes isolated from rat brain. uv irradiation of neuronal nuclei from 60-day-old rats resulted in a 7- to 10-fold stimulation of DNA repair synthesis attributable to DNA polymerase β which, at this developmental stage, is virtually the only DNA polymerase present in the nuclei. No repair synthesis could be elicited by treating the nuclei with N-methyl-N-nitrosourea, but this was probably due to the inability of brain tissue to excise alkylated bases from DNA. The role of DNA polymerase γ was studied in synaptosomes by using a system mimicking in vivo mitochondrial DNA synthesis. By showing that under these conditions, DNA replication occurs in miatochondria, and exploiting the fact that DNA polymerase γ is the only DNA polymerase present in mitochondria, evidence was obtained for a role of DNA polymerase γ in mitochondrial DNA replication. Based on these results and on the wealth of literature on DNA polymerase α, we conclude that DNA polymerase α is mainly responsible for DNA replication in nuclei, DNA polymerase β is involved in nuclear DNA repair, and DNA polymerase γ is the mitochondrial replicating enzyme. However, minor roles for DNA polymerase α in DNA repair or for DNA polymerase β in DNA replication cannot be excluded

  11. Herpes Simplex Virus 1 DNA Polymerase RNase H Activity Acts in a 3'-to-5' Direction and Is Dependent on the 3'-to-5' Exonuclease Active Site.

    Science.gov (United States)

    Lawler, Jessica L; Mukherjee, Purba; Coen, Donald M

    2018-03-01

    The catalytic subunit (Pol) of herpes simplex virus 1 (HSV-1) DNA polymerase has been extensively studied both as a model for other family B DNA polymerases and for its differences from these enzymes as an antiviral target. Among the activities of HSV-1 Pol is an intrinsic RNase H activity that cleaves RNA from RNA-DNA hybrids. There has long been a controversy regarding whether this activity is due to the 3'-to-5' exonuclease of Pol or whether it is a separate activity, possibly acting on 5' RNA termini. To investigate this issue, we compared wild-type HSV-1 Pol and a 3'-to-5' exonuclease-deficient mutant, D368A Pol, for DNA polymerase activity, 3'-to-5' exonuclease activity, and RNase H activity in vitro Additionally, we assessed the RNase H activity using differentially end-labeled templates with 5' or 3' RNA termini. The mutant enzyme was at most modestly impaired for DNA polymerase activity but was drastically impaired for 3'-to-5' exonuclease activity, with no activity detected even at high enzyme-to-DNA substrate ratios. Importantly, the mutant showed no detectable ability to excise RNA with either a 3' or 5' terminus, while the wild-type HSV-1 Pol was able to cleave RNA from the annealed RNA-DNA hairpin template, but only detectably with a 3' RNA terminus in a 3'-to-5' direction and at a rate lower than that of the exonuclease activity. These results suggest that HSV-1 Pol does not have an RNase H separable from its 3'-to-5' exonuclease activity and that this activity prefers DNA degradation over degradation of RNA from RNA-DNA hybrids. IMPORTANCE Herpes simplex virus 1 (HSV-1) is a member of the Herpesviridae family of DNA viruses, several of which cause morbidity and mortality in humans. Although the HSV-1 DNA polymerase has been studied for decades and is a crucial target for antivirals against HSV-1 infection, several of its functions remain to be elucidated. A hypothesis suggesting the existence of a 5'-to-3' RNase H activity intrinsic to this enzyme

  12. A Protein Complex Required for Polymerase V Transcripts and RNA- Directed DNA Methylation in Arabidopsis

    KAUST Repository

    Law, Julie A.; Ausí n, Israel; Johnson, Lianna M.; Vashisht, Ajay  A Amar; Zhu, Jian-Kang; Wohlschlegel, James  A A.; Jacobsen, Steven E.

    2010-01-01

    DNA methylation is an epigenetic modification associated with gene silencing. In Arabidopsis, DNA methylation is established by DOMAINS REARRANGED METHYLTRANSFERASE 2 (DRM2), which is targeted by small interfering RNAs through a pathway termed RNA-directed DNA methylation (RdDM) [1, 2]. Recently, RdDM was shown to require intergenic noncoding (IGN) transcripts that are dependent on the Pol V polymerase. These transcripts are proposed to function as scaffolds for the recruitment of downstream RdDM proteins, including DRM2, to loci that produce both siRNAs and IGN transcripts [3]. However, the mechanism(s) through which Pol V is targeted to specific genomic loci remains largely unknown. Through affinity purification of two known RdDM components, DEFECTIVE IN RNA-DIRECTED DNA METHYLATION 1 (DRD1) [4] and DEFECTIVE IN MERISTEM SILENCING 3 (DMS3) [5, 6], we found that they copurify with each other and with a novel protein, RNA-DIRECTED DNA METHYLATION 1 (RDM1), forming a complex we term DDR. We also found that DRD1 copurified with Pol V subunits and that RDM1, like DRD1 [3] and DMS3 [7], is required for the production of Pol V-dependent transcripts. These results suggest that the DDR complex acts in RdDM at a step upstream of the recruitment or activation of Pol V. © 2010 Elsevier Ltd. All rights reserved.

  13. A Protein Complex Required for Polymerase V Transcripts and RNA- Directed DNA Methylation in Arabidopsis

    KAUST Repository

    Law, Julie A.

    2010-05-01

    DNA methylation is an epigenetic modification associated with gene silencing. In Arabidopsis, DNA methylation is established by DOMAINS REARRANGED METHYLTRANSFERASE 2 (DRM2), which is targeted by small interfering RNAs through a pathway termed RNA-directed DNA methylation (RdDM) [1, 2]. Recently, RdDM was shown to require intergenic noncoding (IGN) transcripts that are dependent on the Pol V polymerase. These transcripts are proposed to function as scaffolds for the recruitment of downstream RdDM proteins, including DRM2, to loci that produce both siRNAs and IGN transcripts [3]. However, the mechanism(s) through which Pol V is targeted to specific genomic loci remains largely unknown. Through affinity purification of two known RdDM components, DEFECTIVE IN RNA-DIRECTED DNA METHYLATION 1 (DRD1) [4] and DEFECTIVE IN MERISTEM SILENCING 3 (DMS3) [5, 6], we found that they copurify with each other and with a novel protein, RNA-DIRECTED DNA METHYLATION 1 (RDM1), forming a complex we term DDR. We also found that DRD1 copurified with Pol V subunits and that RDM1, like DRD1 [3] and DMS3 [7], is required for the production of Pol V-dependent transcripts. These results suggest that the DDR complex acts in RdDM at a step upstream of the recruitment or activation of Pol V. © 2010 Elsevier Ltd. All rights reserved.

  14. Transcription-induced DNA supercoiling: New roles of intranucleosomal DNA loops in DNA repair and transcription.

    Science.gov (United States)

    Gerasimova, N S; Pestov, N A; Kulaeva, O I; Clark, D J; Studitsky, V M

    2016-05-26

    RNA polymerase II (Pol II) transcription through chromatin is accompanied by formation of small intranucleosomal DNA loops. Pol II captured within a small loop drives accumulation of DNA supercoiling, facilitating further transcription. DNA breaks relieve supercoiling and induce Pol II arrest, allowing detection of DNA damage hidden in chromatin structure.

  15. Inhibitory effect of tocotrienol on eukaryotic DNA polymerase λ and angiogenesis

    International Nuclear Information System (INIS)

    Mizushina, Yoshiyuki; Nakagawa, Kiyotaka; Shibata, Akira; Awata, Yasutoshi; Kuriyama, Isoko; Shimazaki, Noriko; Koiwai, Osamu; Uchiyama, Yukinobu; Sakaguchi, Kengo; Miyazawa, Teruo; Yoshida, Hiromi

    2006-01-01

    Tocotrienols, vitamin E compounds that have an unsaturated side chain with three double bonds, selectively inhibited the activity of mammalian DNA polymerase λ (pol λ) in vitro. These compounds did not influence the activities of replicative pols such as α, δ, and ε, or even the activity of pol β which is thought to have a very similar three-dimensional structure to the pol β-like region of pol λ. Since δ-tocotrienol had the strongest inhibitory effect among the four (α- to δ-) tocotrienols, the isomer's structure might be an important factor in the inhibition of pol λ. The inhibitory effect of δ-tocotrienol on both intact pol λ (residues 1-575) and a truncated pol λ lacking the N-terminal BRCA1 C-terminus (BRCT) domain (residues 133-575, del-1 pol λ) was dose-dependent, with 50% inhibition observed at a concentration of 18.4 and 90.1 μM, respectively. However, del-2 pol λ (residues 245-575) containing the C-terminal pol β-like region was unaffected. Tocotrienols also inhibited the proliferation of and formation of tubes by bovine aortic endothelial cells, with δ-tocotrienol having the greatest effect. These results indicated that tocotrienols targeted both pol λ and angiogenesis as anti-cancer agents. The relationship between the inhibition of pol λ and anti-angiogenesis by δ-tocotrienol was discussed

  16. Inactivation of Pol θ and C-NHEJ eliminates off-target integration of exogenous DNA.

    Science.gov (United States)

    Zelensky, Alex N; Schimmel, Joost; Kool, Hanneke; Kanaar, Roland; Tijsterman, Marcel

    2017-07-07

    Off-target or random integration of exogenous DNA hampers precise genomic engineering and presents a safety risk in clinical gene therapy strategies. Genetic definition of random integration has been lacking for decades. Here, we show that the A-family DNA polymerase θ (Pol θ) promotes random integration, while canonical non-homologous DNA end joining plays a secondary role; cells double deficient for polymerase θ and canonical non-homologous DNA end joining are devoid of any integration events, demonstrating that these two mechanisms define random integration. In contrast, homologous recombination is not reduced in these cells and gene targeting is improved to 100% efficiency. Such complete reversal of integration outcome, from predominately random integration to exclusively gene targeting, provides a rational way forward to improve the efficacy and safety of DNA delivery and gene correction approaches.Random off-target integration events can impair precise gene targeting and poses a safety risk for gene therapy. Here the authors show that repression of polymerase θ and classical non-homologous recombination eliminates random integration.

  17. DNA polymerase preference determines PCR priming efficiency.

    Science.gov (United States)

    Pan, Wenjing; Byrne-Steele, Miranda; Wang, Chunlin; Lu, Stanley; Clemmons, Scott; Zahorchak, Robert J; Han, Jian

    2014-01-30

    Polymerase chain reaction (PCR) is one of the most important developments in modern biotechnology. However, PCR is known to introduce biases, especially during multiplex reactions. Recent studies have implicated the DNA polymerase as the primary source of bias, particularly initiation of polymerization on the template strand. In our study, amplification from a synthetic library containing a 12 nucleotide random portion was used to provide an in-depth characterization of DNA polymerase priming bias. The synthetic library was amplified with three commercially available DNA polymerases using an anchored primer with a random 3' hexamer end. After normalization, the next generation sequencing (NGS) results of the amplified libraries were directly compared to the unamplified synthetic library. Here, high throughput sequencing was used to systematically demonstrate and characterize DNA polymerase priming bias. We demonstrate that certain sequence motifs are preferred over others as primers where the six nucleotide sequences at the 3' end of the primer, as well as the sequences four base pairs downstream of the priming site, may influence priming efficiencies. DNA polymerases in the same family from two different commercial vendors prefer similar motifs, while another commercially available enzyme from a different DNA polymerase family prefers different motifs. Furthermore, the preferred priming motifs are GC-rich. The DNA polymerase preference for certain sequence motifs was verified by amplification from single-primer templates. We incorporated the observed DNA polymerase preference into a primer-design program that guides the placement of the primer to an optimal location on the template. DNA polymerase priming bias was characterized using a synthetic library amplification system and NGS. The characterization of DNA polymerase priming bias was then utilized to guide the primer-design process and demonstrate varying amplification efficiencies among three commercially

  18. [Effect of Mn(II) on the error-prone DNA polymerase iota activity in extracts from human normal and tumor cells].

    Science.gov (United States)

    Lakhin, A V; Efremova, A S; Makarova, I V; Grishina, E E; Shram, S I; Tarantul, V Z; Gening, L V

    2013-01-01

    The DNA polymerase iota (Pol iota), which has some peculiar features and is characterized by an extremely error-prone DNA synthesis, belongs to the group of enzymes preferentially activated by Mn2+ instead of Mg2+. In this work, the effect of Mn2+ on DNA synthesis in cell extracts from a) normal human and murine tissues, b) human tumor (uveal melanoma), and c) cultured human tumor cell lines SKOV-3 and HL-60 was tested. Each group displayed characteristic features of Mn-dependent DNA synthesis. The changes in the Mn-dependent DNA synthesis caused by malignant transformation of normal tissues are described. It was also shown that the error-prone DNA synthesis catalyzed by Pol iota in extracts of all cell types was efficiently suppressed by an RNA aptamer (IKL5) against Pol iota obtained in our work earlier. The obtained results suggest that IKL5 might be used to suppress the enhanced activity of Pol iota in tumor cells.

  19. Effect of γ-irradiated DNA on the activity of DNA polymerase

    International Nuclear Information System (INIS)

    Leadon, S.A.; Ward, J.F.

    1981-01-01

    A cell-free assay was developed to measure the effect of γ-irradiated DNA template on the ability of DNA polymerase to copy unirradiated template. Doses as low as 1 krad were able to decrease (approx. 15%) the activity of both bacterial and mammalian DNA polymerases in the assay. The percentage of polymerase activity decreased as the dose received by the template increased. The reduction in DNA polymerase activity was shown to be due to an inhibition of the enzyme by the irradiated DNA. Irradiated poly(dA-dT) was more effective in reducing polymerase activity than calf thymus DNA. Thus the polymerase-inhibition site(s) appears to be associated with base damage, specifically adenine or thymine. Using a free-radical scavenger, OH radicals were found to be involved in producing the damage sites. The interaction between irradiated DNA and DNA polymerase was found to be specific for the enzyme and not for other proteins present in the assay. The inhibition of DNA polymerase occurred prior to or during the initiation of DNA synthesis rather than after initiation of synthesis, i.e., during elongation

  20. Fission yeast shelterin regulates DNA polymerases and Rad3(ATR kinase to limit telomere extension.

    Directory of Open Access Journals (Sweden)

    Ya-Ting Chang

    2013-11-01

    Full Text Available Studies in fission yeast have previously identified evolutionarily conserved shelterin and Stn1-Ten1 complexes, and established Rad3(ATR/Tel1(ATM-dependent phosphorylation of the shelterin subunit Ccq1 at Thr93 as the critical post-translational modification for telomerase recruitment to telomeres. Furthermore, shelterin subunits Poz1, Rap1 and Taz1 have been identified as negative regulators of Thr93 phosphorylation and telomerase recruitment. However, it remained unclear how telomere maintenance is dynamically regulated during the cell cycle. Thus, we investigated how loss of Poz1, Rap1 and Taz1 affects cell cycle regulation of Ccq1 Thr93 phosphorylation and telomere association of telomerase (Trt1(TERT, DNA polymerases, Replication Protein A (RPA complex, Rad3(ATR-Rad26(ATRIP checkpoint kinase complex, Tel1(ATM kinase, shelterin subunits (Tpz1, Ccq1 and Poz1 and Stn1. We further investigated how telomere shortening, caused by trt1Δ or catalytically dead Trt1-D743A, affects cell cycle-regulated telomere association of telomerase and DNA polymerases. These analyses established that fission yeast shelterin maintains telomere length homeostasis by coordinating the differential arrival of leading (Polε and lagging (Polα strand DNA polymerases at telomeres to modulate Rad3(ATR association, Ccq1 Thr93 phosphorylation and telomerase recruitment.

  1. Trans-Lesion DNA Polymerases May Be Involved in Yeast Meiosis

    Science.gov (United States)

    Arbel-Eden, Ayelet; Joseph-Strauss, Daphna; Masika, Hagit; Printzental, Oxana; Rachi, Eléanor; Simchen, Giora

    2013-01-01

    Trans-lesion DNA polymerases (TLSPs) enable bypass of DNA lesions during replication and are also induced under stress conditions. Being only weakly dependent on their template during replication, TLSPs introduce mutations into DNA. The low processivity of these enzymes ensures that they fall off their template after a few bases are synthesized and are then replaced by the more accurate replicative polymerase. We find that the three TLSPs of budding yeast Saccharomyces cerevisiae Rev1, PolZeta (Rev3 and Rev7), and Rad30 are induced during meiosis at a time when DNA double-strand breaks (DSBs) are formed and homologous chromosomes recombine. Strains deleted for one or any combination of the three TLSPs undergo normal meiosis. However, in the triple-deletion mutant, there is a reduction in both allelic and ectopic recombination. We suggest that trans-lesion polymerases are involved in the processing of meiotic double-strand breaks that lead to mutations. In support of this notion, we report significant yeast two-hybrid (Y2H) associations in meiosis-arrested cells between the TLSPs and DSB proteins Rev1-Spo11, Rev1-Mei4, and Rev7-Rec114, as well as between Rev1 and Rad30. We suggest that the involvement of TLSPs in processing of meiotic DSBs could be responsible for the considerably higher frequency of mutations reported during meiosis compared with that found in mitotically dividing cells, and therefore may contribute to faster evolutionary divergence than previously assumed. PMID:23550131

  2. Mechanisms by which herpes simplex virus DNA polymerase limits translesion synthesis through abasic sites.

    Science.gov (United States)

    Zhu, Yali; Song, Liping; Stroud, Jason; Parris, Deborah S

    2008-01-01

    Results suggest a high probability that abasic (AP) sites occur at least once per herpes simplex virus type 1 (HSV-1) genome. The parameters that control the ability of HSV-1 DNA polymerase (pol) to engage in AP translesion synthesis (TLS) were examined because AP lesions could influence the completion and fidelity of viral DNA synthesis. Pre-steady-state kinetic experiments demonstrated that wildtype (WT) and exonuclease-deficient (exo-) pol could incorporate opposite an AP lesion, but full TLS required absence of exo function. Virtually all of the WT pol was bound at the exo site to AP-containing primer-templates (P/Ts) at equilibrium, and the pre-steady-state rate of excision by WT pol was higher on AP-containing than on matched DNA. However, several factors influencing polymerization work synergistically with exo activity to prevent HSV-1 pol from engaging in TLS. Although the pre-steady-state catalytic rate constant for insertion of dATP opposite a T or AP site was similar, ground-state-binding affinity of dATP for insertion opposite an AP site was reduced 3-9-fold. Single-turnover running-start experiments demonstrated a reduced proportion of P/Ts extended to the AP site compared to the preceding site during processive synthesis by WT or exo- pol. Only the exo- pol engaged in TLS, though inefficiently and without burst kinetics, suggesting a much slower rate-limiting step for extension beyond the AP site.

  3. Modulation of Pleurodeles waltl DNA polymerase mu expression by extreme conditions encountered during spaceflight.

    Directory of Open Access Journals (Sweden)

    Véronique Schenten

    Full Text Available DNA polymerase µ is involved in DNA repair, V(DJ recombination and likely somatic hypermutation of immunoglobulin genes. Our previous studies demonstrated that spaceflight conditions affect immunoglobulin gene expression and somatic hypermutation frequency. Consequently, we questioned whether Polμ expression could also be affected. To address this question, we characterized Polμ of the Iberian ribbed newt Pleurodeles waltl and exposed embryos of that species to spaceflight conditions or to environmental modifications corresponding to those encountered in the International Space Station. We noted a robust expression of Polμ mRNA during early ontogenesis and in the testis, suggesting that Polμ is involved in genomic stability. Full-length Polμ transcripts are 8-9 times more abundant in P. waltl than in humans and mice, thereby providing an explanation for the somatic hypermutation predilection of G and C bases in amphibians. Polμ transcription decreases after 10 days of development in space and radiation seem primarily involved in this down-regulation. However, space radiation, alone or in combination with a perturbation of the circadian rhythm, did not affect Polμ protein levels and did not induce protein oxidation, showing the limited impact of radiation encountered during a 10-day stay in the International Space Station.

  4. Time-lapse crystallography snapshots of a double-strand break repair polymerase in action.

    Science.gov (United States)

    Jamsen, Joonas A; Beard, William A; Pedersen, Lars C; Shock, David D; Moon, Andrea F; Krahn, Juno M; Bebenek, Katarzyna; Kunkel, Thomas A; Wilson, Samuel H

    2017-08-15

    DNA polymerase (pol) μ is a DNA-dependent polymerase that incorporates nucleotides during gap-filling synthesis in the non-homologous end-joining pathway of double-strand break repair. Here we report time-lapse X-ray crystallography snapshots of catalytic events during gap-filling DNA synthesis by pol μ. Unique catalytic intermediates and active site conformational changes that underlie catalysis are uncovered, and a transient third (product) metal ion is observed in the product state. The product manganese coordinates phosphate oxygens of the inserted nucleotide and PP i . The product metal is not observed during DNA synthesis in the presence of magnesium. Kinetic analyses indicate that manganese increases the rate constant for deoxynucleoside 5'-triphosphate insertion compared to magnesium. The likely product stabilization role of the manganese product metal in pol μ is discussed. These observations provide insight on structural attributes of this X-family double-strand break repair polymerase that impact its biological function in genome maintenance.DNA polymerase (pol) μ functions in DNA double-strand break repair. Here the authors use time-lapse X-ray crystallography to capture the states of pol µ during the conversion from pre-catalytic to product complex and observe a third transiently bound metal ion in the product state.

  5. Insertion of the T3 DNA polymerase thioredoxin binding domain enhances the processivity and fidelity of Taq DNA polymerase

    OpenAIRE

    Davidson, John F.; Fox, Richard; Harris, Dawn D.; Lyons-Abbott, Sally; Loeb, Lawrence A.

    2003-01-01

    Insertion of the T3 DNA polymerase thioredoxin binding domain (TBD) into the distantly related thermostable Taq DNA polymerase at an analogous position in the thumb domain, converts the Taq DNA polymerase from a low processive to a highly processive enzyme. Processivity is dependent on the presence of thioredoxin. The enhancement in processivity is 20–50-fold when compared with the wild-type Taq DNA polymerase or to the recombinant polymerase in the absence of thioredoxin. The recombinant Taq...

  6. dNTP pool levels modulate mutator phenotypes of error-prone DNA polymerase ε variants.

    Science.gov (United States)

    Williams, Lindsey N; Marjavaara, Lisette; Knowels, Gary M; Schultz, Eric M; Fox, Edward J; Chabes, Andrei; Herr, Alan J

    2015-05-12

    Mutator phenotypes create genetic diversity that fuels tumor evolution. DNA polymerase (Pol) ε mediates leading strand DNA replication. Proofreading defects in this enzyme drive a number of human malignancies. Here, using budding yeast, we show that mutator variants of Pol ε depend on damage uninducible (Dun)1, an S-phase checkpoint kinase that maintains dNTP levels during a normal cell cycle and up-regulates dNTP synthesis upon checkpoint activation. Deletion of DUN1 (dun1Δ) suppresses the mutator phenotype of pol2-4 (encoding Pol ε proofreading deficiency) and is synthetically lethal with pol2-M644G (encoding altered Pol ε base selectivity). Although pol2-4 cells cycle normally, pol2-M644G cells progress slowly through S-phase. The pol2-M644G cells tolerate deletions of mediator of the replication checkpoint (MRC) 1 (mrc1Δ) and radiation sensitive (Rad) 9 (rad9Δ), which encode mediators of checkpoint responses to replication stress and DNA damage, respectively. The pol2-M644G mutator phenotype is partially suppressed by mrc1Δ but not rad9Δ; neither deletion suppresses the pol2-4 mutator phenotype. Thus, checkpoint activation augments the Dun1 effect on replication fidelity but is not required for it. Deletions of genes encoding key Dun1 targets that negatively regulate dNTP synthesis, suppress the dun1Δ pol2-M644G synthetic lethality and restore the mutator phenotype of pol2-4 in dun1Δ cells. DUN1 pol2-M644G cells have constitutively high dNTP levels, consistent with checkpoint activation. In contrast, pol2-4 and POL2 cells have similar dNTP levels, which decline in the absence of Dun1 and rise in the absence of the negative regulators of dNTP synthesis. Thus, dNTP pool levels correlate with Pol ε mutator severity, suggesting that treatments targeting dNTP pools could modulate mutator phenotypes for therapy.

  7. An RNA polymerase II-and AGO4-associated protein acts in RNA-directed DNA methylation

    KAUST Repository

    Gao, Zhihuan

    2010-04-21

    DNA methylation is an important epigenetic mark in many eukaryotes. In plants, 24-nucleotide small interfering RNAs (siRNAs) bound to the effector protein, Argonaute 4 (AGO4), can direct de novo DNA methylation by the methyltransferase DRM2 (refs 2, 4-6). Here we report a new regulator of RNA-directed DNA methylation (RdDM) in Arabidopsis: RDM1. Loss-of-function mutations in the RDM1 gene impair the accumulation of 24-nucleotide siRNAs, reduce DNA methylation, and release transcriptional gene silencing at RdDM target loci. RDM1 encodes a small protein that seems to bind single-stranded methyl DNA, and associates and co-localizes with RNA polymerase II (Pol II, also known as NRPB), AGO4 and DRM2 in the nucleus. Our results indicate that RDM1 is a component of the RdDM effector complex and may have a role in linking siRNA production with pre-existing or de novo cytosine methylation. Our results also indicate that, although RDM1 and Pol V (also known as NRPE) may function together at some RdDM target sites in the peri-nucleolar siRNA processing centre, Pol II rather than Pol V is associated with the RdDM effector complex at target sites in the nucleoplasm. © 2010 Macmillan Publishers Limited. All rights reserved.

  8. Error-Prone Translesion DNA Synthesis by Escherichia coli DNA Polymerase IV (DinB on Templates Containing 1,2-dihydro-2-oxoadenine

    Directory of Open Access Journals (Sweden)

    Masaki Hori

    2010-01-01

    Full Text Available Escherichia coli DNA polymerase IV (Pol IV is involved in bypass replication of damaged bases in DNA. Reactive oxygen species (ROS are generated continuously during normal metabolism and as a result of exogenous stress such as ionizing radiation. ROS induce various kinds of base damage in DNA. It is important to examine whether Pol IV is able to bypass oxidatively damaged bases. In this study, recombinant Pol IV was incubated with oligonucleotides containing thymine glycol (dTg, 5-formyluracil (5-fodU, 5-hydroxymethyluracil (5-hmdU, 7,8-dihydro-8-oxoguanine (8-oxodG and 1,2-dihydro-2-oxoadenine (2-oxodA. Primer extension assays revealed that Pol IV preferred to insert dATP opposite 5-fodU and 5-hmdU, while it inefficiently inserted nucleotides opposite dTg. Pol IV inserted dCTP and dATP opposite 8-oxodG, while the ability was low. It inserted dCTP more effectively than dTTP opposite 2-oxodA. Pol IV's ability to bypass these lesions decreased in the order: 2-oxodA > 5-fodU~5-hmdU > 8-oxodG > dTg. The fact that Pol IV preferred to insert dCTP opposite 2-oxodA suggests the mutagenic potential of 2-oxodA leading to A:T→G:C transitions. Hydrogen peroxide caused an ~2-fold increase in A:T→G:C mutations in E. coli, while the increase was significantly greater in E. coli overexpressing Pol IV. These results indicate that Pol IV may be involved in ROS-enhanced A:T→G:C mutations.

  9. Translesion Synthesis of the N2-2′-Deoxyguanosine Adduct of the Dietary Mutagen IQ in Human Cells: Error-Free Replication by DNA Polymerase κ and Mutagenic Bypass by DNA Polymerases η, ζ, and Rev1

    Science.gov (United States)

    2016-01-01

    Translesion synthesis (TLS) of the N2-2′-deoxyguanosine (dG-N2-IQ) adduct of the carcinogen 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) was investigated in human embryonic kidney 293T cells by replicating plasmid constructs in which the adduct was individually placed at each guanine (G1, G2, or G3) of the NarI sequence (5′-CG1G2CG3CC-3′). TLS efficiency was 38%, 29%, and 25% for the dG-N2-IQ located at G1, G2, and G3, respectively, which suggests that dG-N2-IQ is bypassed more efficiently by one or more DNA polymerases at G1 than at either G2 or G3. TLS efficiency was decreased 8–35% in cells with knockdown of pol η, pol κ, pol ι, pol ζ, or Rev1. Up to 75% reduction in TLS occurred when pol η, pol ζ, and Rev1 were simultaneously knocked down, suggesting that these three polymerases play important roles in dG-N2-IQ bypass. Mutation frequencies (MFs) of dG-N2-IQ at G1, G2, and G3 were 23%, 17%, and 11%, respectively, exhibiting a completely reverse trend of the previously reported MF of the C8-dG adduct of IQ (dG-C8-IQ), which is most mutagenic at G3 ((2015) Nucleic Acids Res.43, 8340−835126220181). The major type of mutation induced by dG-N2-IQ was targeted G → T, as was reported for dG-C8-IQ. In each site, knockdown of pol κ resulted in an increase in MF, whereas MF was reduced when pol η, pol ι, pol ζ, or Rev1 was knocked down. The reduction in MF was most pronounced when pol η, pol ζ, and Rev1 were simultaneously knocked down and especially when the adduct was located at G3, where MF was reduced by 90%. We conclude that pol κ predominantly performs error-free TLS of the dG-N2-IQ adduct, whereas pols η, pol ζ, and Rev1 cooperatively carry out the error-prone TLS. However, in vitro experiments using yeast pol ζ and κ showed that the former was inefficient in full-length primer extension on dG-N2-IQ templates, whereas the latter was efficient in both error-free and error-prone extensions. We believe that the observed differences between

  10. DNA polymerase gamma inhibition by vitamin K3 induces mitochondria-mediated cytotoxicity in human cancer cells.

    Science.gov (United States)

    Sasaki, Ryohei; Suzuki, Yoko; Yonezawa, Yuko; Ota, Yosuke; Okamoto, Yoshiaki; Demizu, Yusuke; Huang, Peng; Yoshida, Hiromi; Sugimura, Kazuro; Mizushina, Yoshiyuki

    2008-05-01

    Among the vitamin K (VK) compounds, VK3 exhibits distinct cytotoxic activity in cancer cells and is thought to affect redox cycling; however, the underlying mechanisms remain unclear. Here we demonstrate that VK3 selectively inhibits DNA polymerase (pol) gamma, the key enzyme responsible for mitochondrial DNA replication and repair. VK3 at 30 microM inhibited pol gamma by more than 80%, caused impairment of mitochondrial DNA replication and repair, and induced a significant increase in reactive oxygen species (ROS), leading to apoptosis. At a lower concentration (3 microM), VK3 did not cause a significant increase in ROS, but was able to effectively inhibit cell proliferation, which could be reversed by supplementing glycolytic substrates. The cytotoxic action of VK3 was independent of p53 tumor suppressor gene status. Interestingly, VK3 only inhibited pol gamma but did not affect other pol including human pol alpha, pol beta, pol delta, and pol epsilon. VK1 and VK2 exhibited no inhibitory effect on any of the pol tested. These data together suggest that the inhibition of pol gamma by VK3 is relatively specific, and that this compound seems to exert its anticancer activity by two possible mechanisms in a concentration-dependent manner: (1) induction of ROS-mediated cell death at high concentrations; and (2) inhibition of cell proliferation at lower concentrations likely through the suppression of mitochondrial respiratory function. These findings may explain various cytotoxic actions induced by VK3, and may pave the way for the further use of VK3.

  11. Influence of DNA Lesions on Polymerase-Mediated DNA Replication at Single-Molecule Resolution.

    Science.gov (United States)

    Gahlon, Hailey L; Romano, Louis J; Rueda, David

    2017-11-20

    Faithful replication of DNA is a critical aspect in maintaining genome integrity. DNA polymerases are responsible for replicating DNA, and high-fidelity polymerases do this rapidly and at low error rates. Upon exposure to exogenous or endogenous substances, DNA can become damaged and this can alter the speed and fidelity of a DNA polymerase. In this instance, DNA polymerases are confronted with an obstacle that can result in genomic instability during replication, for example, by nucleotide misinsertion or replication fork collapse. It is important to know how DNA polymerases respond to damaged DNA substrates to understand the mechanism of mutagenesis and chemical carcinogenesis. Single-molecule techniques have helped to improve our current understanding of DNA polymerase-mediated DNA replication, as they enable the dissection of mechanistic details that can otherwise be lost in ensemble-averaged experiments. These techniques have also been used to gain a deeper understanding of how single DNA polymerases behave at the site of the damage in a DNA substrate. In this review, we evaluate single-molecule studies that have examined the interaction between DNA polymerases and damaged sites on a DNA template.

  12. An AP endonuclease 1-DNA polymerase beta complex: theoretical prediction of interacting surfaces.

    Directory of Open Access Journals (Sweden)

    Alexej Abyzov

    2008-04-01

    Full Text Available Abasic (AP sites in DNA arise through both endogenous and exogenous mechanisms. Since AP sites can prevent replication and transcription, the cell contains systems for their identification and repair. AP endonuclease (APEX1 cleaves the phosphodiester backbone 5' to the AP site. The cleavage, a key step in the base excision repair pathway, is followed by nucleotide insertion and removal of the downstream deoxyribose moiety, performed most often by DNA polymerase beta (pol-beta. While yeast two-hybrid studies and electrophoretic mobility shift assays provide evidence for interaction of APEX1 and pol-beta, the specifics remain obscure. We describe a theoretical study designed to predict detailed interacting surfaces between APEX1 and pol-beta based on published co-crystal structures of each enzyme bound to DNA. Several potentially interacting complexes were identified by sliding the protein molecules along DNA: two with pol-beta located downstream of APEX1 (3' to the damaged site and three with pol-beta located upstream of APEX1 (5' to the damaged site. Molecular dynamics (MD simulations, ensuring geometrical complementarity of interfaces, enabled us to predict interacting residues and calculate binding energies, which in two cases were sufficient (approximately -10.0 kcal/mol to form a stable complex and in one case a weakly interacting complex. Analysis of interface behavior during MD simulation and visual inspection of interfaces allowed us to conclude that complexes with pol-beta at the 3'-side of APEX1 are those most likely to occur in vivo. Additional multiple sequence analyses of APEX1 and pol-beta in related organisms identified a set of correlated mutations of specific residues at the predicted interfaces. Based on these results, we propose that pol-beta in the open or closed conformation interacts and makes a stable interface with APEX1 bound to a cleaved abasic site on the 3' side. The method described here can be used for analysis in

  13. RNA-DNA Differences Are Generated in Human Cells within Seconds after RNA Exits Polymerase II

    Directory of Open Access Journals (Sweden)

    Isabel X. Wang

    2014-03-01

    Full Text Available RNA sequences are expected to be identical to their corresponding DNA sequences. Here, we found all 12 types of RNA-DNA sequence differences (RDDs in nascent RNA. Our results show that RDDs begin to occur in RNA chains ∼55 nt from the RNA polymerase II (Pol II active site. These RDDs occur so soon after transcription that they are incompatible with known deaminase-mediated RNA-editing mechanisms. Moreover, the 55 nt delay in appearance indicates that they do not arise during RNA synthesis by Pol II or as a direct consequence of modified base incorporation. Preliminary data suggest that RDD and R-loop formations may be coupled. These findings identify sequence substitution as an early step in cotranscriptional RNA processing.

  14. Interaction of gold nanoparticles with Pfu DNA polymerase and effect on polymerase chain reaction.

    Science.gov (United States)

    Sun, L-P; Wang, S; Zhang, Z-W; Ma, Y-Y; Lai, Y-Q; Weng, J; Zhang, Q-Q

    2011-03-01

    The interaction of gold nanoparticles with Pfu DNA polymerase has been investigated by a number of biological, optical and electronic spectroscopic techniques. Polymerase chain reaction was performed to show gold nanoparticles' biological effect. Ultraviolet-visible and circular dichroism spectra analysis were applied to character the structure of Pfu DNA polymerase after conjugation with gold nanoparticles. X-ray photoelectron spectroscopy was used to investigate the bond properties of the polymerase-gold nanoparticles complex. The authors demonstrate that gold nanoparticles do not affect the amplification efficiency of polymerase chain reaction using Pfu DNA polymerase, and Pfu DNA polymerase displays no significant changes of the secondary structure upon interaction with gold nanoparticles. The adsorption of Pfu DNA polymerase to gold nanoparticles is mainly through Au-NH(2) bond and electrostatic interaction. These findings may have important implications regarding the safety issue as gold nanoparticles are widely used in biomedical applications.

  15. Thioredoxin suppresses microscopic hopping of T7 DNA polymerase on duplex DNA

    NARCIS (Netherlands)

    Etson, Candice M.; Hamdan, Samir M.; Richardson, Charles C.; Oijen, Antoine M. van; Richardson, Charles C.

    2010-01-01

    The DNA polymerases involved in DNA replication achieve high processivity of nucleotide incorporation by forming a complex with processivity factors. A model system for replicative DNA polymerases, the bacteriophage T7 DNA polymerase (gp5), encoded by gene 5, forms a tight, 1:1 complex with

  16. Sensitivity of human cells expressing low-fidelity or weak-catalytic-activity variants of DNA polymerase ζ to genotoxic stresses.

    Science.gov (United States)

    Suzuki, Tetsuya; Grúz, Petr; Honma, Masamitsu; Adachi, Noritaka; Nohmi, Takehiko

    2016-09-01

    Translesion DNA polymerases (TLS pols) play critical roles in defense mechanisms against genotoxic agents. The defects or mutations of TLS pols are predicted to result in hypersensitivity of cells to environmental mutagens. In this study, human cells expressing DNA polymerase ζ (Pol ζ) variants with low fidelity or weak catalytic activity have been established with Nalm-6-MSH+ cells and their sensitivity to mutagenicity and cytotoxicity of benzo[a]pyrene diol epoxide (BPDE) and ultraviolet-C light (UV-C) was examined. The low-fidelity mutants were engineered by knocking-in DNA sequences that direct changes of leucine 2618 to either phenylalanine (L2618F) or methionine (L2618M) of Pol ζ. The weak-catalytic-activity mutants were generated by knocking-in DNA sequences that direct changes of either tyrosine 2779 to phenylalanine (Y2779F) or aspartate 2781 to asparagine (D2781N). In addition, a +1 frameshift mutation, i.e., CCC to CCCC, was introduced in the coding region of the TK1 gene to measure the mutant frequencies. Doubling time and spontaneous TK mutant frequencies of the established cell lines were similar to those of the wild-type cells. The low-fidelity mutants displayed, however, higher sensitivity to the mutagenicity of BPDE and UV-C than the wild-type cells although their cytotoxic sensitivity was not changed. In contrast, the weak-catalytic-activity mutants were more sensitive to the cytotoxicity of BPDE and UV-C than the wild-type cells, and displayed much higher sensitivity to the clastogenicity of BPDE than the wild-type cells in an in vitro micronucleus assay. These results indicate that human Pol ζ is involved in TLS across DNA lesions induced by BPDE and UV-C and also that the TLS plays important roles in induction of mutations, clastogenicity and in cellular survival of the damaged human cells. Similarities and differences in in vivo roles of yeast and human Pol ζ in genome integrity are discussed. Copyright © 2016 Elsevier B.V. All rights

  17. Inaccurate DNA synthesis in cell extracts of yeast producing active human DNA polymerase iota.

    Science.gov (United States)

    Makarova, Alena V; Grabow, Corinn; Gening, Leonid V; Tarantul, Vyacheslav Z; Tahirov, Tahir H; Bessho, Tadayoshi; Pavlov, Youri I

    2011-01-31

    Mammalian Pol ι has an unusual combination of properties: it is stimulated by Mn(2+) ions, can bypass some DNA lesions and misincorporates "G" opposite template "T" more frequently than incorporates the correct "A." We recently proposed a method of detection of Pol ι activity in animal cell extracts, based on primer extension opposite the template T with a high concentration of only two nucleotides, dGTP and dATP (incorporation of "G" versus "A" method of Gening, abbreviated as "misGvA"). We provide unambiguous proof of the "misGvA" approach concept and extend the applicability of the method for the studies of variants of Pol ι in the yeast model system with different cation cofactors. We produced human Pol ι in baker's yeast, which do not have a POLI ortholog. The "misGvA" activity is absent in cell extracts containing an empty vector, or producing catalytically dead Pol ι, or Pol ι lacking exon 2, but is robust in the strain producing wild-type Pol ι or its catalytic core, or protein with the active center L62I mutant. The signature pattern of primer extension products resulting from inaccurate DNA synthesis by extracts of cells producing either Pol ι or human Pol η is different. The DNA sequence of the template is critical for the detection of the infidelity of DNA synthesis attributed to DNA Pol ι. The primer/template and composition of the exogenous DNA precursor pool can be adapted to monitor replication fidelity in cell extracts expressing various error-prone Pols or mutator variants of accurate Pols. Finally, we demonstrate that the mutation rates in yeast strains producing human DNA Pols ι and η are not elevated over the control strain, despite highly inaccurate DNA synthesis by their extracts.

  18. Inaccurate DNA synthesis in cell extracts of yeast producing active human DNA polymerase iota.

    Directory of Open Access Journals (Sweden)

    Alena V Makarova

    2011-01-01

    Full Text Available Mammalian Pol ι has an unusual combination of properties: it is stimulated by Mn(2+ ions, can bypass some DNA lesions and misincorporates "G" opposite template "T" more frequently than incorporates the correct "A." We recently proposed a method of detection of Pol ι activity in animal cell extracts, based on primer extension opposite the template T with a high concentration of only two nucleotides, dGTP and dATP (incorporation of "G" versus "A" method of Gening, abbreviated as "misGvA". We provide unambiguous proof of the "misGvA" approach concept and extend the applicability of the method for the studies of variants of Pol ι in the yeast model system with different cation cofactors. We produced human Pol ι in baker's yeast, which do not have a POLI ortholog. The "misGvA" activity is absent in cell extracts containing an empty vector, or producing catalytically dead Pol ι, or Pol ι lacking exon 2, but is robust in the strain producing wild-type Pol ι or its catalytic core, or protein with the active center L62I mutant. The signature pattern of primer extension products resulting from inaccurate DNA synthesis by extracts of cells producing either Pol ι or human Pol η is different. The DNA sequence of the template is critical for the detection of the infidelity of DNA synthesis attributed to DNA Pol ι. The primer/template and composition of the exogenous DNA precursor pool can be adapted to monitor replication fidelity in cell extracts expressing various error-prone Pols or mutator variants of accurate Pols. Finally, we demonstrate that the mutation rates in yeast strains producing human DNA Pols ι and η are not elevated over the control strain, despite highly inaccurate DNA synthesis by their extracts.

  19. DNA Polymerases Drive DNA Sequencing-by-Synthesis Technologies: Both Past and Present

    Directory of Open Access Journals (Sweden)

    Cheng-Yao eChen

    2014-06-01

    Full Text Available Next-generation sequencing (NGS technologies have revolutionized modern biological and biomedical research. The engines responsible for this innovation are DNA polymerases; they catalyze the biochemical reaction for deriving template sequence information. In fact, DNA polymerase has been a cornerstone of DNA sequencing from the very beginning. E. coli DNA polymerase I proteolytic (Klenow fragment was originally utilized in Sanger's dideoxy chain terminating DNA sequencing chemistry. From these humble beginnings followed an explosion of organism-specific, genome sequence information accessible via public database. Family A/B DNA polymerases from mesophilic/thermophilic bacteria/archaea were modified and tested in today's standard capillary electrophoresis (CE and NGS sequencing platforms. These enzymes were selected for their efficient incorporation of bulky dye-terminator and reversible dye-terminator nucleotides respectively. Third generation, real-time single molecule sequencing platform requires slightly different enzyme properties. Enterobacterial phage ⱷ29 DNA polymerase copies long stretches of DNA and possesses a unique capability to efficiently incorporate terminal phosphate-labeled nucleoside polyphosphates. Furthermore, ⱷ29 enzyme has also been utilized in emerging DNA sequencing technologies including nanopore-, and protein-transistor-based sequencing. DNA polymerase is, and will continue to be, a crucial component of sequencing technologies.

  20. Repair of Clustered Damage and DNA Polymerase Iota.

    Science.gov (United States)

    Belousova, E A; Lavrik, O I

    2015-08-01

    Multiple DNA lesions occurring within one or two turns of the DNA helix known as clustered damage are a source of double-stranded DNA breaks, which represent a serious threat to the cells. Repair of clustered lesions is accomplished in several steps. If a clustered lesion contains oxidized bases, an individual DNA lesion is repaired by the base excision repair (BER) mechanism involving a specialized DNA polymerase after excising DNA damage. Here, we investigated DNA synthesis catalyzed by DNA polymerase iota using damaged DNA templates. Two types of DNA substrates were used as model DNAs: partial DNA duplexes containing breaks of different length, and DNA duplexes containing 5-formyluracil (5-foU) and uracil as a precursor of apurinic/apyrimidinic sites (AP) in opposite DNA strands. For the first time, we showed that DNA polymerase iota is able to catalyze DNA synthesis using partial DNA duplexes having breaks of different length as substrates. In addition, we found that DNA polymerase iota could catalyze DNA synthesis during repair of clustered damage via the BER system by using both undamaged and 5-foU-containing templates. We found that hPCNA (human proliferating cell nuclear antigen) increased efficacy of DNA synthesis catalyzed by DNA polymerase iota.

  1. Two distinct modes of RecA action are required for DNA polymerase V-catalyzed translesion synthesis.

    Science.gov (United States)

    Pham, Phuong; Seitz, Erica M; Saveliev, Sergei; Shen, Xuan; Woodgate, Roger; Cox, Michael M; Goodman, Myron F

    2002-08-20

    SOS mutagenesis in Escherichia coli requires DNA polymerase V (pol V) and RecA protein to copy damaged DNA templates. Here we show that two distinct biochemical modes for RecA protein are necessary for pol V-catalyzed translesion synthesis. One RecA mode is characterized by a strong stimulation in nucleotide incorporation either directly opposite a lesion or at undamaged template sites, but by the absence of lesion bypass. A separate RecA mode is necessary for translesion synthesis. The RecA1730 mutant protein, which was identified on the basis of its inability to promote pol V (UmuD'(2)C)-dependent UV-mutagenesis, appears proficient for the first mode of RecA action but is deficient in the second mode. Data are presented suggesting that the two RecA modes are "nonfilamentous". That is, contrary to current models for SOS mutagenesis, formation of a RecA nucleoprotein filament may not be required for copying damaged DNA templates. Instead, SOS mutagenesis occurs when pol V interacts with two RecA molecules, first at a 3' primer end, upstream of a template lesion, where RecA mode 1 stimulates pol V activity, and subsequently at a site immediately downstream of the lesion, where RecA mode 2 cocatalyzes lesion bypass. We posit that in vivo assembly of a RecA nucleoprotein filament may be required principally to target pol V to a site of DNA damage and to stabilize the pol V-RecA interaction at the lesion. However, it is only a RecA molecule located at the 3' filament tip, proximal to a damaged template base, that is directly responsible for translesion synthesis.

  2. Viewing Human DNA Polymerase β Faithfully and Unfaithfully Bypass an Oxidative Lesion by Time-Dependent Crystallography

    Science.gov (United States)

    Vyas, Rajan; Reed, Andrew J.; Tokarsky, E. John; Suo, Zucai

    2015-01-01

    One common oxidative DNA lesion, 8-oxo-7,8-dihydro-2′-deoxyguanine (8-oxoG), is highly mutagenic in vivo due to its anti-conformation forming a Watson–Crick base pair with correct deoxycytidine 5′-triphosphate (dCTP) and its syn-conformation forming a Hoogsteen base pair with incorrect deoxyadenosine 5′-triphosphate (dATP). Here, we utilized time-resolved X-ray crystallography to follow 8-oxoG bypass by human DNA polymerase β (hPolβ). In the 12 solved structures, both Watson–Crick (anti-8-oxoG:anti-dCTP) and Hoogsteen (syn-8-oxoG:anti-dATP) base pairing were clearly visible and were maintained throughout the chemical reaction. Additionally, a third Mg2+ appeared during the process of phosphodiester bond formation and was located between the reacting α- and β-phosphates of the dNTP, suggesting its role in stabilizing reaction intermediates. After phosphodiester bond formation, hPolβ reopened its conformation, pyrophosphate was released, and the newly incorporated primer 3′-terminal nucleotide stacked, rather than base paired, with 8-oxoG. These structures provide the first real-time pictures, to our knowledge, of how a polymerase correctly and incorrectly bypasses a DNA lesion. PMID:25825995

  3. Roles of POLD4, smallest subunit of DNA polymerase {delta}, in nuclear structures and genomic stability of human cells

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Qin Miao [Division of Molecular Carcinogenesis, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya (Japan); Akashi, Tomohiro [Division of Molecular Mycology and Medicine, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya (Japan); Masuda, Yuji; Kamiya, Kenji [Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima 734-8553 (Japan); Takahashi, Takashi [Division of Molecular Carcinogenesis, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya (Japan); Suzuki, Motoshi, E-mail: msuzuki@med.nagoya-u.ac.jp [Division of Molecular Carcinogenesis, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya (Japan)

    2010-01-01

    Mammalian DNA polymerase {delta} (pol {delta}) is essential for DNA replication, though the functions of this smallest subunit of POLD4 have been elusive. We investigated pol {delta} activities in vitro and found that it was less active in the absence of POLD4, irrespective of the presence of the accessory protein PCNA. shRNA-mediated reduction of POLD4 resulted in a marked decrease in colony formation activity by Calu6, ACC-LC-319, and PC-10 cells. We also found that POLD4 reduction was associated with an increased population of karyomere-like cells, which may be an indication of DNA replication stress and/or DNA damage. The karyomere-like cells retained an ability to progress through the cell cycle, suggesting that POLD4 reduction induces modest genomic instability, while allowing cells to grow until DNA damage reaches an intolerant level. Our results indicate that POLD4 is required for the in vitro pol {delta} activity, and that it functions in cell proliferation and maintenance of genomic stability of human cells.

  4. Roles of POLD4, smallest subunit of DNA polymerase δ, in nuclear structures and genomic stability of human cells

    International Nuclear Information System (INIS)

    Huang, Qin Miao; Akashi, Tomohiro; Masuda, Yuji; Kamiya, Kenji; Takahashi, Takashi; Suzuki, Motoshi

    2010-01-01

    Mammalian DNA polymerase δ (pol δ) is essential for DNA replication, though the functions of this smallest subunit of POLD4 have been elusive. We investigated pol δ activities in vitro and found that it was less active in the absence of POLD4, irrespective of the presence of the accessory protein PCNA. shRNA-mediated reduction of POLD4 resulted in a marked decrease in colony formation activity by Calu6, ACC-LC-319, and PC-10 cells. We also found that POLD4 reduction was associated with an increased population of karyomere-like cells, which may be an indication of DNA replication stress and/or DNA damage. The karyomere-like cells retained an ability to progress through the cell cycle, suggesting that POLD4 reduction induces modest genomic instability, while allowing cells to grow until DNA damage reaches an intolerant level. Our results indicate that POLD4 is required for the in vitro pol δ activity, and that it functions in cell proliferation and maintenance of genomic stability of human cells.

  5. DNA polymerase zeta cooperates with polymerases kappa and iota in translesion DNA synthesis across pyrimidine photodimers in cells from XPV patients.

    Science.gov (United States)

    Ziv, Omer; Geacintov, Nicholas; Nakajima, Satoshi; Yasui, Akira; Livneh, Zvi

    2009-07-14

    Human cells tolerate UV-induced cyclobutane pyrimidine dimers (CPD) by translesion DNA synthesis (TLS), carried out by DNA polymerase eta, the POLH gene product. A deficiency in DNA polymerase eta due to germ-line mutations in POLH causes the hereditary disease xeroderma pigmentosum variant (XPV), which is characterized by sunlight sensitivity and extreme predisposition to sunlight-induced skin cancer. XPV cells are UV hypermutable due to the activity of mutagenic TLS across CPD, which explains the cancer predisposition of the patients. However, the identity of the backup polymerase that carries out this mutagenic TLS was unclear. Here, we show that DNA polymerase zeta cooperates with DNA polymerases kappa and iota to carry out error-prone TLS across a TT CPD. Moreover, DNA polymerases zeta and kappa, but not iota, protect XPV cells against UV cytotoxicity, independently of nucleotide excision repair. This presents an extreme example of benefit-risk balance in the activity of TLS polymerases, which provide protection against UV cytotoxicity at the cost of increased mutagenic load.

  6. DNA polymerase ζ cooperates with polymerases κ and ι in translesion DNA synthesis across pyrimidine photodimers in cells from XPV patients

    Science.gov (United States)

    Ziv, Omer; Geacintov, Nicholas; Nakajima, Satoshi; Yasui, Akira; Livneh, Zvi

    2009-01-01

    Human cells tolerate UV-induced cyclobutane pyrimidine dimers (CPD) by translesion DNA synthesis (TLS), carried out by DNA polymerase η, the POLH gene product. A deficiency in DNA polymerase η due to germ-line mutations in POLH causes the hereditary disease xeroderma pigmentosum variant (XPV), which is characterized by sunlight sensitivity and extreme predisposition to sunlight-induced skin cancer. XPV cells are UV hypermutable due to the activity of mutagenic TLS across CPD, which explains the cancer predisposition of the patients. However, the identity of the backup polymerase that carries out this mutagenic TLS was unclear. Here, we show that DNA polymerase ζ cooperates with DNA polymerases κ and ι to carry out error-prone TLS across a TT CPD. Moreover, DNA polymerases ζ and κ, but not ι, protect XPV cells against UV cytotoxicity, independently of nucleotide excision repair. This presents an extreme example of benefit-risk balance in the activity of TLS polymerases, which provide protection against UV cytotoxicity at the cost of increased mutagenic load. PMID:19564618

  7. COMPARISON OF SIX COMMERCIALLY-AVAILABLE DNA POLYMERASES FOR DIRECT PCR

    Directory of Open Access Journals (Sweden)

    Masashi Miura

    2013-12-01

    Full Text Available SUMMARY The use of a “direct PCR” DNA polymerase enables PCR amplification without any prior DNA purification from blood samples due to the enzyme's resistance to inhibitors present in blood components. Such DNA polymerases are now commercially available. We compared the PCR performance of six direct PCR-type DNA polymerases (KOD FX, Mighty Amp, Hemo KlenTaq, Phusion Blood II, KAPA Blood, and BIOTAQ in dried blood eluted from a filter paper with TE buffer. GoTaq Flexi was used as a standard DNA polymerase. PCR performance was evaluated by a nested PCR technique for detecting Plasmodium falciparum genomic DNA in the presence of the blood components. Although all six DNA polymerases showed resistance to blood components compared to the standard Taq polymerase, the KOD FX and BIOTAQ DNA polymerases were resistant to inhibitory blood components at concentrations of 40%, and their PCR performance was superior to that of other DNA polymerases. When the reaction mixture contained a mild detergent, only KOD FX DNA polymerase retained the original amount of amplified product. These results indicate that KOD FX DNA polymerase is the most resistant to inhibitory blood components and/or detergents. Thus, KOD FX DNA polymerase could be useful in serological studies to simultaneously detect antibodies and DNA in eluents for antibodies. KOD FX DNA polymerase is thus not limited to use in detecting malaria parasites, but could also be employed to detect other blood-borne pathogens.

  8. Escherichia coli DnaE Polymerase Couples Pyrophosphatase Activity to DNA Replication.

    Directory of Open Access Journals (Sweden)

    Fabio Lapenta

    Full Text Available DNA Polymerases generate pyrophosphate every time they catalyze a step of DNA elongation. This elongation reaction is generally believed as thermodynamically favoured by the hydrolysis of pyrophosphate, catalyzed by inorganic pyrophosphatases. However, the specific action of inorganic pyrophosphatases coupled to DNA replication in vivo was never demonstrated. Here we show that the Polymerase-Histidinol-Phosphatase (PHP domain of Escherichia coli DNA Polymerase III α subunit features pyrophosphatase activity. We also show that this activity is inhibited by fluoride, as commonly observed for inorganic pyrophosphatases, and we identified 3 amino acids of the PHP active site. Remarkably, E. coli cells expressing variants of these catalytic residues of α subunit feature aberrant phenotypes, poor viability, and are subject to high mutation frequencies. Our findings indicate that DNA Polymerases can couple DNA elongation and pyrophosphate hydrolysis, providing a mechanism for the control of DNA extension rate, and suggest a promising target for novel antibiotics.

  9. Accommodation of an N-(deoxyguanosin-8-yl)-2-acetylaminofluorene adduct in the active site of human DNA polymerase ι: Hoogsteen or Watson-Crick base pairing?†

    Science.gov (United States)

    Donny-Clark, Kerry; Shapiro, Robert; Broyde, Suse

    2009-01-01

    Bypass across DNA lesions by specialized polymerases is essential for maintenance of genomic stability. Human DNA polymerase ι (polι) is a bypass polymerase of the Y family. Crystal structures of polι suggest that Hoogsteen base pairing is employed to bypass minor groove DNA lesions, placing them on the spacious major groove side of the enzyme. Primer extension studies have shown that polι is also capable of error-free nucleotide incorporation opposite the bulky major groove adduct N-(deoxyguanosin-8-yl)-2-acetyl-aminofluorene (dG-AAF). We present molecular dynamics simulations and free energy calculations suggesting that Watson-Crick base pairing could be employed in polι for bypass of dG-AAF. In polι with Hoogsteen paired dG-AAF the bulky AAF moiety would reside on the cramped minor groove side of the template. The Hoogsteen-capable conformation distorts the active site, disrupting interactions necessary for error-free incorporation of dC opposite the lesion. Watson-Crick pairing places the AAF rings on the spacious major groove side, similar to the position of minor groove adducts observed with Hoogsteen pairing. Watson-Crick paired structures show a well-ordered active site, with a near reaction-ready ternary complex. Thus our results suggest that polι would utilize the same spacious region for lesion bypass of both major and minor groove adducts. Therefore, purine adducts with bulk on the minor groove side would use Hoogsteen pairing, while adducts with the bulky lesion on the major groove side would utilize Watson-Crick base pairing as indicated by our MD simulations for dG-AAF. This suggests the possibility of an expanded role for polι in lesion bypass. PMID:19072536

  10. Double-stranded DNA translocase activity of transcription factor TFIIH and the mechanism of RNA polymerase II open complex formation.

    Science.gov (United States)

    Fishburn, James; Tomko, Eric; Galburt, Eric; Hahn, Steven

    2015-03-31

    Formation of the RNA polymerase II (Pol II) open complex (OC) requires DNA unwinding mediated by the transcription factor TFIIH helicase-related subunit XPB/Ssl2. Because XPB/Ssl2 binds DNA downstream from the location of DNA unwinding, it cannot function using a conventional helicase mechanism. Here we show that yeast TFIIH contains an Ssl2-dependent double-stranded DNA translocase activity. Ssl2 tracks along one DNA strand in the 5' → 3' direction, implying it uses the nontemplate promoter strand to reel downstream DNA into the Pol II cleft, creating torsional strain and leading to DNA unwinding. Analysis of the Ssl2 and DNA-dependent ATPase activity of TFIIH suggests that Ssl2 has a processivity of approximately one DNA turn, consistent with the length of DNA unwound during transcription initiation. Our results can explain why maintaining the OC requires continuous ATP hydrolysis and the function of TFIIH in promoter escape. Our results also suggest that XPB/Ssl2 uses this translocase mechanism during DNA repair rather than physically wedging open damaged DNA.

  11. Effects of Intermediates between Vitamins K2 and K3 on Mammalian DNA Polymerase Inhibition and Anti-Inflammatory Activity

    Directory of Open Access Journals (Sweden)

    Takeshi Azuma

    2011-02-01

    Full Text Available Previously, we reported that vitamin K3 (VK3, but not VK1 or VK2 (=MK-4, inhibits the activity of human DNA polymerase γ (pol γ. In this study, we chemically synthesized three intermediate compounds between VK2 and VK3, namely MK-3, MK-2 and MK-1, and investigated the inhibitory effects of all five compounds on the activity of mammalian pols. Among these compounds, MK-2 was the strongest inhibitor of mammalian pols α, κ and λ, which belong to the B, Y and X families of pols, respectively; whereas VK3 was the strongest inhibitor of human pol γ, an A-family pol. MK-2 potently inhibited the activity of all animal species of pol tested, and its inhibitory effect on pol λ activity was the strongest with an IC50 value of 24.6 μM. However, MK-2 did not affect the activity of plant or prokaryotic pols, or that of other DNA metabolic enzymes such as primase of pol α, RNA polymerase, polynucleotide kinase or deoxyribonuclease I. Because we previously found a positive relationship between pol λ inhibition and anti-inflammatory action, we examined whether these compounds could inhibit inflammatory responses. Among the five compounds tested, MK-2 caused the greatest reduction in 12-O-tetradecanoylphorbol-13-acetate (TPA-induced acute inflammation in mouse ear. In addition, in a cell culture system using mouse macrophages, MK-2 displayed the strongest suppression of the production of tumor necrosis factor (TNF-α induced by lipopolysaccharide (LPS. Moreover, MK-2 was found to inhibit the action of nuclear factor (NF-κB. In an in vivo mouse model of LPS-evoked acute inflammation, intraperitoneal injection of MK-2 in mice led to suppression of TNF-α production in serum. In conclusion, this study has identified VK2 and VK3 intermediates, such as MK-2, that are promising anti-inflammatory candidates.

  12. [DNA-dependent DNA polymerase induced by herpes virus papio (HVP) in producing cells].

    Science.gov (United States)

    D'iachenko, A G; Beriia, L Ia; Matsenko, L D; Kakubava, V V; Kokosh, L V

    1980-11-01

    A new DNA polymerase was found in the cells of suspension lymphoblastoid cultures, which produce lymphotropic baboon herpes virus (HVP). The enzyme was isolated in a partially purified form. In some properties the enzyme differs from other cellular DNA polymerases. The HVP-induced DNA polymerase has the molecular weight of 1,6 x 10(5) and sedimentation coefficient of about 8S. The enzyme is resistant to high salt concentrations and N-ethylmaleimide, but shows a pronounced sensitivity to phosphonoacetate. The enzyme effectively copies "activated" DNA and synthetic deoxyribohomopolymers. The attempts to detect the DNA polymerase activity in HVP virions were unsuccessful.

  13. Enhancement of DNA polymerase activity in potato tuber slices

    International Nuclear Information System (INIS)

    Watanabe, Akira; Imaseki, Hidemasa

    1977-01-01

    DNA polymerase was extracted from potato (Soleum tuberosum L.) tuber discs and the temporal correlation of its activity change to DNA synthesis in vivo was examined during aging of the discs. Most of the DNA polymerase was recovered as a bound form in the 18,000 x g precipitate. Reaction with the bound-form enzyme was dependent on the presence of four deoxynucleoside triphosphates, Mg 2+ , and a template. ''Activated'' DNA and heat-denatured DNA, but not native DNA, were utilized as templates. The polymerase activity was sensitive to SH reagents. Fresh discs, which do not synthesize DNA in vivo, contained a significant amount of DNA polymerase and its activity increased linearly with time until 48 hr after slicing and became four times that of fresh discs after 72 hr, whereas the activity of DNA synthesis in vivo increased with time and decreased after reaching a maximum at 30 hr. Cycloheximide inhibited the enhancement of polymerase activity. DNA polymerase from aged and fresh discs had identical requirements for deoxynucleotides and a template in their reactions, sensitivity to SH reagent, and affinity to thymidine triphosphate. (auth.)

  14. DNA polymerase. beta. reaction with ultraviolet-irradiated DNA incised by correndonuclease

    Energy Technology Data Exchange (ETDEWEB)

    Nowak, R; Zarebska, Z [Instytut Onkologii, Warsaw (Poland); Zmudzka, B [Polska Akademia Nauk, Warsaw. Inst. Biochemii i Biofizyki

    1980-09-19

    Covalently closed circular Col E1 DNA was ultraviolet-irradiated with a dose of 60 J/m/sup 2/, thus introducing about 3.2 pyrimidine dimers per DNA molecule. Treatment of irradiated Col E1 DNA with Micrococcus luteus correndonuclease resulted, in the vicinity of pyrimidine dimers, in an average of 3.3 incisions per DNA molecule, and converted DNA to the open circular form. Incised Col E1 DNA stimulated no reaction with calf thymus DNA polymerase ..cap alpha.. but was recognized as a template by DNA polymerase ..beta... The latter enzyme incorporated about 1.6 molecules of dTMP (corresponding to 6 molecules of dNMP) per one correndonuclease incision. The length of the DNA polymerase ..beta.. product was comparable to the anticipated length of the DNA region within which the hydrogen bonds were disrupted owing to dimer formation. The enzyme required Mg/sup 2 +/ and four dNTPs for reaction and was resistant to N-ethylmaleimide or p-mercuribenzoate.

  15. DNA Polymerase Fidelity: Beyond Right and Wrong.

    Science.gov (United States)

    Washington, M Todd

    2016-11-01

    Accurate DNA replication depends on the ability of DNA polymerases to discriminate between correctly and incorrectly paired nucleotides. In this issue of Structure, Batra et al. (2016) show the structural basis for why DNA polymerases do not efficiently add correctly paired nucleotides immediately after incorporating incorrectly paired ones. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Bypass of a psoralen DNA interstrand cross-link by DNA polymerases beta, iota, and kappa in vitro

    Science.gov (United States)

    Smith, Leigh A.; Makarova, Alena V.; Samson, Laura; Thiesen, Katherine E.; Dhar, Alok; Bessho, Tadayoshi

    2012-01-01

    Repair of DNA inter-strand cross-links in mammalian cells involves several biochemically distinctive processes, including the release of one of the cross-linked strands and translesion DNA synthesis (TLS). In this report, we investigated in vitro TLS activity of psoralen DNA inter-strand cross-link by three DNA repair polymerases, DNA polymerase beta, kappa and iota. DNA polymerase beta is capable of bypassing a psoralen cross-link with a low efficiency. Cell extracts prepared from DNA polymerase beta knockout mouse embryonic fibroblast showed a reduced bypass activity of the psoralen cross-link and purified DNA polymerase beta restored the bypass activity. In addition, DNA polymerase iota mis-incorporated thymine across the psoralen cross-link and DNA polymerase kappa extended these mis-paired primer ends, suggesting that DNA polymerase iota may serve as an inserter and DNA polymerase kappa may play a role as an extender in the repair of psoralen DNA inter-strand cross-links. The results demonstrated here indicate that multiple DNA polymerases could participate in TLS steps in mammalian DNA inter-strand cross-link repair. PMID:23106263

  17. Developing Inhibitors of Translesion DNA Synthesis as Therapeutic Agents Against Lung Cancer

    Science.gov (United States)

    2014-10-01

    pol eta when replicating damaged DNA. 1S. SUBJECT TERMS: Mutagenesis, DNA polymerases, nucleoside analogs, chemotherapeutic agents 16. SECURITY ...such as polymerase eta, iota , and kappa that are involved in replicating damaged DNA. Our kinetic data obtained under Task 1B indicates that pol eta

  18. DNA Polymerases λ and β: The Double-Edged Swords of DNA Repair

    Directory of Open Access Journals (Sweden)

    Elisa Mentegari

    2016-08-01

    Full Text Available DNA is constantly exposed to both endogenous and exogenous damages. More than 10,000 DNA modifications are induced every day in each cell’s genome. Maintenance of the integrity of the genome is accomplished by several DNA repair systems. The core enzymes for these pathways are the DNA polymerases. Out of 17 DNA polymerases present in a mammalian cell, at least 13 are specifically devoted to DNA repair and are often acting in different pathways. DNA polymerases β and λ are involved in base excision repair of modified DNA bases and translesion synthesis past DNA lesions. Polymerase λ also participates in non-homologous end joining of DNA double-strand breaks. However, recent data have revealed that, depending on their relative levels, the cell cycle phase, the ratio between deoxy- and ribo-nucleotide pools and the interaction with particular auxiliary proteins, the repair reactions carried out by these enzymes can be an important source of genetic instability, owing to repair mistakes. This review summarizes the most recent results on the ambivalent properties of these enzymes in limiting or promoting genetic instability in mammalian cells, as well as their potential use as targets for anticancer chemotherapy.

  19. DNA Polymerases λ and β: The Double-Edged Swords of DNA Repair.

    Science.gov (United States)

    Mentegari, Elisa; Kissova, Miroslava; Bavagnoli, Laura; Maga, Giovanni; Crespan, Emmanuele

    2016-08-31

    DNA is constantly exposed to both endogenous and exogenous damages. More than 10,000 DNA modifications are induced every day in each cell's genome. Maintenance of the integrity of the genome is accomplished by several DNA repair systems. The core enzymes for these pathways are the DNA polymerases. Out of 17 DNA polymerases present in a mammalian cell, at least 13 are specifically devoted to DNA repair and are often acting in different pathways. DNA polymerases β and λ are involved in base excision repair of modified DNA bases and translesion synthesis past DNA lesions. Polymerase λ also participates in non-homologous end joining of DNA double-strand breaks. However, recent data have revealed that, depending on their relative levels, the cell cycle phase, the ratio between deoxy- and ribo-nucleotide pools and the interaction with particular auxiliary proteins, the repair reactions carried out by these enzymes can be an important source of genetic instability, owing to repair mistakes. This review summarizes the most recent results on the ambivalent properties of these enzymes in limiting or promoting genetic instability in mammalian cells, as well as their potential use as targets for anticancer chemotherapy.

  20. The replicative DNA polymerase of herpes simplex virus 1 exhibits apurinic/apyrimidinic and 5′-deoxyribose phosphate lyase activities

    Science.gov (United States)

    Bogani, Federica; Boehmer, Paul E.

    2008-01-01

    Base excision repair (BER) is essential for maintaining genome stability both to counter the accumulation of unusual bases and to protect from base loss in the DNA. Herpes simplex virus 1 (HSV-1) is a large dsDNA virus that encodes its own DNA replication machinery, including enzymes involved in nucleotide metabolism. We report on a replicative family B and a herpesvirus-encoded DNA Pol that possesses DNA lyase activity. We have discovered that the catalytic subunit of the HSV-1 DNA polymerase (Pol) (UL30) exhibits apurinic/apyrimidinic (AP) and 5′-deoxyribose phosphate (dRP) lyase activities. These activities are integral to BER and lead to DNA cleavage on the 3′ side of abasic sites and 5′-dRP residues that remain after cleavage by 5′-AP endonuclease. The UL30-catalyzed reaction occurs independently of divalent cation and proceeds via a Schiff base intermediate, indicating that it occurs via a lyase mechanism. Partial proteolysis of the Schiff base shows that the DNA lyase activity resides in the Pol domain of UL30. These observations together with the presence of a virus-encoded uracil DNA glycosylase indicates that HSV-1 has the capacity to perform critical steps in BER. These findings have implications on the role of BER in viral genome maintenance during lytic replication and reactivation from latency. PMID:18695225

  1. Discovery of cyanophage genomes which contain mitochondrial DNA polymerase.

    Science.gov (United States)

    Chan, Yi-Wah; Mohr, Remus; Millard, Andrew D; Holmes, Antony B; Larkum, Anthony W; Whitworth, Anna L; Mann, Nicholas H; Scanlan, David J; Hess, Wolfgang R; Clokie, Martha R J

    2011-08-01

    DNA polymerase γ is a family A DNA polymerase responsible for the replication of mitochondrial DNA in eukaryotes. The origins of DNA polymerase γ have remained elusive because it is not present in any known bacterium, though it has been hypothesized that mitochondria may have inherited the enzyme by phage-mediated nonorthologous displacement. Here, we present an analysis of two full-length homologues of this gene, which were found in the genomes of two bacteriophages, which infect the chlorophyll-d containing cyanobacterium Acaryochloris marina. Phylogenetic analyses of these phage DNA polymerase γ proteins show that they branch deeply within the DNA polymerase γ clade and therefore share a common origin with their eukaryotic homologues. We also found homologues of these phage polymerases in the environmental Community Cyberinfrastructure for Advanced Microbial Ecology Research and Analysis (CAMERA) database, which fell in the same clade. An analysis of the CAMERA assemblies containing the environmental homologues together with the filter fraction metadata indicated some of these assemblies may be of bacterial origin. We also show that the phage-encoded DNA polymerase γ is highly transcribed as the phage genomes are replicated. These findings provide data that may assist in reconstructing the evolution of mitochondria.

  2. Anti-tumor effects of novel 5-O-acyl plumbagins based on the inhibition of mammalian DNA replicative polymerase activity.

    Directory of Open Access Journals (Sweden)

    Moe Kawamura

    Full Text Available We previously found that vitamin K3 (menadione, 2-methyl-1,4-naphthoquinone inhibits the activity of human mitochondrial DNA polymerase γ (pol γ. In this study, we focused on plumbagin (5-hydroxy-2-methyl-1,4-naphthoquinone, and chemically synthesized novel plumbagins conjugated with C2:0 to C22:6 fatty acids (5-O-acyl plumbagins. These chemically modified plumbagins enhanced mammalian pol inhibition and their cytotoxic activity. Plumbagin conjugated with chains consisting of more than C18-unsaturated fatty acids strongly inhibited the activities of calf pol α and human pol γ. Plumbagin conjugated with oleic acid (C18:1-acyl plumbagin showed the strongest suppression of human colon carcinoma (HCT116 cell proliferation among the ten synthesized 5-O-acyl plumbagins. The inhibitory activity on pol α, a DNA replicative pol, by these compounds showed high correlation with their cancer cell proliferation suppressive activity. C18:1-Acyl plumbagin selectively inhibited the activities of mammalian pol species, but did not influence the activities of other pols and DNA metabolic enzymes tested. This compound inhibited the proliferation of various human cancer cell lines, and was the cytotoxic inhibitor showing strongest inhibition towards HT-29 colon cancer cells (LD50 = 2.9 µM among the nine cell lines tested. In an in vivo anti-tumor assay conducted on nude mice bearing solid tumors of HT-29 cells, C18:1-acyl plumbagin was shown to be a promising tumor suppressor. These data indicate that novel 5-O-acyl plumbagins act as anti-cancer agents based on mammalian DNA replicative pol α inhibition. Moreover, the results suggest that acylation of plumbagin is an effective chemical modification to improve the anti-cancer activity of vitamin K3 derivatives, such as plumbagin.

  3. Cooperation between catalytic and DNA binding domains enhances thermostability and supports DNA synthesis at higher temperatures by thermostable DNA polymerases.

    Science.gov (United States)

    Pavlov, Andrey R; Pavlova, Nadejda V; Kozyavkin, Sergei A; Slesarev, Alexei I

    2012-03-13

    We have previously introduced a general kinetic approach for comparative study of processivity, thermostability, and resistance to inhibitors of DNA polymerases [Pavlov, A. R., et al. (2002) Proc. Natl. Acad. Sci. U.S.A.99, 13510-13515]. The proposed method was successfully applied to characterize hybrid DNA polymerases created by fusing catalytic DNA polymerase domains with various sequence-nonspecific DNA binding domains. Here we use the developed kinetic analysis to assess basic parameters of DNA elongation by DNA polymerases and to further study the interdomain interactions in both previously constructed and new chimeric DNA polymerases. We show that connecting helix-hairpin-helix (HhH) domains to catalytic polymerase domains can increase thermostability, not only of DNA polymerases from extremely thermophilic species but also of the enzyme from a faculatative thermophilic bacterium Bacillus stearothermophilus. We also demonstrate that addition of Topo V HhH domains extends efficient DNA synthesis by chimerical polymerases up to 105 °C by maintaining processivity of DNA synthesis at high temperatures. We found that reversible high-temperature structural transitions in DNA polymerases decrease the rates of binding of these enzymes to the templates. Furthermore, activation energies and pre-exponential factors of the Arrhenius equation suggest that the mechanism of electrostatic enhancement of diffusion-controlled association plays a minor role in binding of templates to DNA polymerases.

  4. Cooperation between Catalytic and DNA-binding Domains Enhances Thermostability and Supports DNA Synthesis at Higher Temperatures by Thermostable DNA Polymerases

    Science.gov (United States)

    Pavlov, Andrey R.; Pavlova, Nadejda V.; Kozyavkin, Sergei A.; Slesarev, Alexei I.

    2012-01-01

    We have previously introduced a general kinetic approach for comparative study of processivity, thermostability, and resistance to inhibitors of DNA polymerases (Pavlov et. al., (2002) Proc. Natl. Acad. Sci. USA 99, 13510–13515). The proposed method was successfully applied to characterize hybrid DNA polymerases created by fusing catalytic DNA polymerase domains with various non-specific DNA binding domains. Here we use the developed kinetic analysis to assess basic parameters of DNA elongation by DNA polymerases and to further study the interdomain interactions in both previously constructed and new chimeric DNA polymerases. We show that connecting Helix-hairpin-Helix (HhH) domains to catalytic polymerase domains can increase thermostability, not only of DNA polymerases from extremely thermophilic species, but also of the enzyme from a faculatative thermophilic bacterium Bacillus stearothermophilus. We also demonstrate that addition of TopoV HhH domains extends efficient DNA synthesis by chimerical polymerases up to 105°C by maintaining processivity of DNA synthesis at high temperatures. We also found that reversible high-temperature structural transitions in DNA polymerases decrease the rates of binding of these enzymes to the templates. Furthermore, activation energies and pre-exponential factors of the Arrhenius equation suggest that the mechanism of electrostatic enhancement of diffusion-controlled association plays a minor role in binding templates to DNA polymerases. PMID:22320201

  5. Inhibiting DNA Polymerases as a Therapeutic Intervention against Cancer

    Directory of Open Access Journals (Sweden)

    Anthony J. Berdis

    2017-11-01

    Full Text Available Inhibiting DNA synthesis is an important therapeutic strategy that is widely used to treat a number of hyperproliferative diseases including viral infections, autoimmune disorders, and cancer. This chapter describes two major categories of therapeutic agents used to inhibit DNA synthesis. The first category includes purine and pyrmidine nucleoside analogs that directly inhibit DNA polymerase activity. The second category includes DNA damaging agents including cisplatin and chlorambucil that modify the composition and structure of the nucleic acid substrate to indirectly inhibit DNA synthesis. Special emphasis is placed on describing the molecular mechanisms of these inhibitory effects against chromosomal and mitochondrial DNA polymerases. Discussions are also provided on the mechanisms associated with resistance to these therapeutic agents. A primary focus is toward understanding the roles of specialized DNA polymerases that by-pass DNA lesions produced by DNA damaging agents. Finally, a section is provided that describes emerging areas in developing new therapeutic strategies targeting specialized DNA polymerases.

  6. The role of hRev7, the accessory subunit of hPolζ, in translesion synthesis past DNA damage induced by benzo[a]pyrene diol epoxide (BPDE

    Directory of Open Access Journals (Sweden)

    Maher Veronica M

    2010-12-01

    Full Text Available Abstract Background DNA polymerase zeta (Polζ is a specialized DNA polymerase that, unlike classical replicative polymerases, is capable of replicating past DNA lesions, i.e. of performing translesion synthesis (TLS. The catalytic subunit of hPolζ, hRev3, has been shown to play a critical role in DNA damage-induced mutagenesis in human cells, but less is known about the role of hRev7, the accessory subunit of hPolζ, in such mutagenesis. To address this question, we recently generated human fibroblasts with very significantly reduced levels of hRev7 protein and demonstrated that hRev7 is required to protect cells from ultraviolet(254 nm (UV radiation-induced cytotoxicity and mutagenesis (McNally et al., DNA Repair 7 (2008 597-604. The goal of the present study was to determine whether hRev7 is similarly involved in the tolerance of DNA damage induced by benzo[a]pyrene diol epoxide (BPDE, the reactive form of the widespread environmental carcinogen benzo[a]pyrene. Methods To determine whether hRev7 also plays a role in protecting human cells from the cytotoxicity and mutagenesis induced by benzo[a]pyrene diol epoxide (BPDE, cell strains with reduced hRev7 were compared to their parental strain and a vector control strain for the effect of BPDE on cell survival, induction of mutations, and the ability to progress through the cell cycle. Results The results show that cell strains with reduced hRev7 are more sensitive to the cytotoxic effect of BPDE than the control strains, and progress through S-phase at a slower rate than the control cells following BPDE treatment, indicating that hRev7, and likely hPolζ, is required for efficient bypass of BPDE-induced DNA lesions. However, neither the frequency nor kinds of mutations induced by BPDE in cells with reduced hRev7 differ significantly from those induced in the control strains, suggesting that hPolζ is not essential for inserting nucleotides opposite BPDE-induced DNA damage. Conclusions Taken

  7. Optimal conditions to use Pfu exo(-) DNA polymerase for highly efficient ligation-mediated polymerase chain reaction protocols.

    Science.gov (United States)

    Angers, M; Cloutier, J F; Castonguay, A; Drouin, R

    2001-08-15

    Ligation-Mediated Polymerase Chain Reaction (LMPCR) is the most sensitive sequencing technique available to map single-stranded DNA breaks at the nucleotide level of resolution using genomic DNA. LMPCR has been adapted to map DNA damage and reveal DNA-protein interactions inside living cells. However, the sequence context (GC content), the global break frequency and the current combination of DNA polymerases used in LMPCR affect the quality of the results. In this study, we developed and optimized an LMPCR protocol adapted for Pyrococcus furiosus exo(-) DNA polymerase (Pfu exo(-)). The relative efficiency of Pfu exo(-) was compared to T7-modified DNA polymerase (Sequenase 2.0) at the primer extension step and to Thermus aquaticus DNA polymerase (Taq) at the PCR amplification step of LMPCR. At all break frequencies tested, Pfu exo(-) proved to be more efficient than Sequenase 2.0. During both primer extension and PCR amplification steps, the ratio of DNA molecules per unit of DNA polymerase was the main determinant of the efficiency of Pfu exo(-), while the efficiency of Taq was less affected by this ratio. Substitution of NaCl for KCl in the PCR reaction buffer of Taq strikingly improved the efficiency of the DNA polymerase. Pfu exo(-) was clearly more efficient than Taq to specifically amplify extremely GC-rich genomic DNA sequences. Our results show that a combination of Pfu exo(-) at the primer extension step and Taq at the PCR amplification step is ideal for in vivo DNA analysis and DNA damage mapping using LMPCR.

  8. Inhibition of DNA replication, DNA repair synthesis, and DNA polymerases α and δ by butylphenyl deoxyguanosine triphosphate

    International Nuclear Information System (INIS)

    Dreslor, S.L.; Frattini, M.G.

    1987-01-01

    Semiconservative DNA replication in growing mammalian cells and ultraviolet (UV)-induced DNA repair synthesis in nongrowing mammalian cells are mediated by one or both of the aphidicolin-sensitive DNA polymerases, α and/or δ. They have studied the inhibition of replication and repair synthesis in permeable human cells by N 2 (p-n-butylphenyl)-2'-deoxyguanosine-5'-triphosphate (BuPh dGTP), an agent which inhibits polymerase α strongly and polymerase δ weakly. Both processes are inhibited by BuPh-dGTP in competition with dGTP. The K/sub i/'s are, for replication, 2-3 μM and, for repair synthesis, 3-4 μM, consistent with the involvement of the same DNA polymerase in both processes. Inhibition of isolated human polymerase α by BuPh-dGTP is also competitive with dGTP, but the K/sub i/ is approximately 10 nM, several hundred-fold lower than the K/sub i/'s of replication and repair synthesis. Isolated polymerase δ is inhibited by BuPh-dGTP at doses similar to those which inhibit replication and repair synthesis, however, attempts to determine the K/sub i/ of polymerase δ were hampered by the finding that the dependence of δ activity on deoxyribunucleotide concentration is parabolic at low doses. This behavior differs from the behavior of polymerase α and of cellular DNA replication and repair synthesis, all of which show a simple, hyperbolic relationship between activity and deoxyribonucleotide concentration. Thus, inhibition of DNA replication and UV induced DNA repair synthesis by BuPh dGTP is quantitatively similar to DNA polymerase δ, but some other characteristics of the cellular processes are more similar to those of polymerase α

  9. Molecular basis for PrimPol recruitment to replication forks by RPA.

    Science.gov (United States)

    Guilliam, Thomas A; Brissett, Nigel C; Ehlinger, Aaron; Keen, Benjamin A; Kolesar, Peter; Taylor, Elaine M; Bailey, Laura J; Lindsay, Howard D; Chazin, Walter J; Doherty, Aidan J

    2017-05-23

    DNA damage and secondary structures can stall the replication machinery. Cells possess numerous tolerance mechanisms to complete genome duplication in the presence of such impediments. In addition to translesion synthesis (TLS) polymerases, most eukaryotic cells contain a multifunctional replicative enzyme called primase-polymerase (PrimPol) that is capable of directly bypassing DNA damage by TLS, as well as repriming replication downstream of impediments. Here, we report that PrimPol is recruited to reprime through its interaction with RPA. Using biophysical and crystallographic approaches, we identify that PrimPol possesses two RPA-binding motifs and ascertained the key residues required for these interactions. We demonstrate that one of these motifs is critical for PrimPol's recruitment to stalled replication forks in vivo. In addition, biochemical analysis reveals that RPA serves to stimulate the primase activity of PrimPol. Together, these findings provide significant molecular insights into PrimPol's mode of recruitment to stalled forks to facilitate repriming and restart.

  10. RNA Pol II promotes transcription of centromeric satellite DNA in beetles.

    Directory of Open Access Journals (Sweden)

    Zeljka Pezer

    Full Text Available Transcripts of centromeric satellite DNAs are known to play a role in heterochromatin formation as well as in establishment of the kinetochore. However, little is known about basic mechanisms of satellite DNA expression within constitutive heterochromatin and its regulation. Here we present comprehensive analysis of transcription of abundant centromeric satellite DNA, PRAT from beetle Palorus ratzeburgii (Coleoptera. This satellite is characterized by preservation and extreme sequence conservation among evolutionarily distant insect species. PRAT is expressed in all three developmental stages: larvae, pupae and adults at similar level. Transcripts are abundant comprising 0.033% of total RNA and are heterogeneous in size ranging from 0.5 kb up to more than 5 kb. Transcription proceeds from both strands but with 10 fold different expression intensity and transcripts are not processed into siRNAs. Most of the transcripts (80% are not polyadenylated and remain in the nucleus while a small portion is exported to the cytoplasm. Multiple, irregularly distributed transcription initiation sites as well as termination sites have been mapped within the PRAT sequence using primer extension and RLM-RACE. The presence of cap structure as well as poly(A tails in a portion of the transcripts indicate RNA polymerase II-dependent transcription and a putative polymerase II promoter site overlaps the most conserved part of the PRAT sequence. The treatment of larvae with alpha-amanitin decreases the level of PRAT transcripts at concentrations that selectively inhibit pol II activity. In conclusion, stable, RNA polymerase II dependant transcripts of abundant centromeric satellite DNA, not regulated by RNAi, have been identified and characterized. This study offers a basic understanding of expression of highly abundant heterochromatic DNA which in beetle species constitutes up to 50% of the genome.

  11. Structures of an Apo and a Binary Complex of an Evolved Archeal B Family DNA Polymerase Capable of Synthesising Highly Cy-Dye Labelled DNA

    Science.gov (United States)

    Wynne, Samantha A.; Pinheiro, Vitor B.; Holliger, Philipp; Leslie, Andrew G. W.

    2013-01-01

    Thermophilic DNA polymerases of the polB family are of great importance in biotechnological applications including high-fidelity PCR. Of particular interest is the relative promiscuity of engineered versions of the exo- form of polymerases from the Thermo- and Pyrococcales families towards non-canonical substrates, which enables key advances in Next-generation sequencing. Despite this there is a paucity of structural information to guide further engineering of this group of polymerases. Here we report two structures, of the apo form and of a binary complex of a previously described variant (E10) of Pyrococcus furiosus (Pfu) polymerase with an ability to fully replace dCTP with Cyanine dye-labeled dCTP (Cy3-dCTP or Cy5-dCTP) in PCR and synthesise highly fluorescent “CyDNA” densely decorated with cyanine dye heterocycles. The apo form of Pfu-E10 closely matches reported apo form structures of wild-type Pfu. In contrast, the binary complex (in the replicative state with a duplex DNA oligonucleotide) reveals a closing movement of the thumb domain, increasing the contact surface with the nascent DNA duplex strand. Modelling based on the binary complex suggests how bulky fluorophores may be accommodated during processive synthesis and has aided the identification of residues important for the synthesis of unnatural nucleic acid polymers. PMID:23940661

  12. Effect of DNA polymerase inhibitors on DNA repair in intact and permeable human fibroblasts: Evidence that DNA polymerases δ and β are involved in DNA repair synthesis induced by N-methyl-N'-nitro-N-nitrosoguanidine

    International Nuclear Information System (INIS)

    Hammond, R.A.; Miller, M.R.; McClung, J.K.

    1990-01-01

    The involvement of DNA polymerases α, β, and δ in DNA repair synthesis induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) was investigated in human fibroblasts (HF). The effects of anti-(DNA polymerase α) monoclonal antibody, (p-n-butylphenyl)deoxyguanosine triphosphate (BuPdGTP), dideoxythymidine triphosphate (ddTTP), and aphidicolin on MNNG-induced DNA repair synthesis were investigated to dissect the roles of the different DNA polymerases. A subcellular system (permeable cells), in which DNA repair synthesis and DNA replication were differentiated by CsCl gradient centrifugation of BrdUMP density-labeled DNA, was used to examine the effects of the polymerase inhibitors. Another approach investigated the effects of several of these inhibitors of MNNG-induced DNA repair synthesis in intact cells by measuring the amount of [ 3 H]thymidine incorporated into repair DNA as determined by autoradiography and quantitation with an automated video image analysis system. In permeable cells, MNNG-induced DNA repair synthesis was inhibited 56% by 50 μg of aphidicolin/mL, 6% by 10 μM BuPdGTP, 13% by anti-(DNA polymerse α) monoclonal antibodies, and 29% by ddTTP. In intact cells, MNNG-induced DNA repair synthesis was inhibited 57% by 50 μg of aphidicolin/mL and was not significantly inhibited by microinjecting anti-(DNA polymerase α) antibodies into HF nuclei. These results indicate that both DNA polymerase δ and β are involved in repairing DNA damage caused by MNNG

  13. General misincorporation frequency: Re-evaluation of the fidelity of DNA polymerases.

    Science.gov (United States)

    Yang, Jie; Li, Bianbian; Liu, Xiaoying; Tang, Hong; Zhuang, Xiyao; Yang, Mingqi; Xu, Ying; Zhang, Huidong; Yang, Chun

    2018-02-19

    DNA replication in cells is performed in the presence of four dNTPs and four rNTPs. In this study, we re-evaluated the fidelity of DNA polymerases using the general misincorporation frequency consisting of three incorrect dNTPs and four rNTPs but not using the traditional special misincorporation frequency with only the three incorrect dNTPs. We analyzed both the general and special misincorporation frequencies of nucleotide incorporation opposite dG, rG, or 8-oxoG by Pseudomonas aeruginosa phage 1 (PaP1) DNA polymerase Gp90 or Sulfolobus solfataricus DNA polymerase Dpo4. Both misincorporation frequencies of other DNA polymerases published were also summarized and analyzed. The general misincorporation frequency is obviously higher than the special misincorporation frequency for many DNA polymerases, indicating the real fidelity of a DNA polymerase should be evaluated using the general misincorporation frequency. Copyright © 2018 Elsevier Inc. All rights reserved.

  14. The proofreading 3'→5' exonuclease activity of DNA polymerases: a kinetic barrier to translesion DNA synthesis

    International Nuclear Information System (INIS)

    Khare, Vineeta; Eckert, Kristin A.

    2002-01-01

    The 3'→5' exonuclease activity intrinsic to several DNA polymerases plays a primary role in genetic stability; it acts as a first line of defense in correcting DNA polymerase errors. A mismatched basepair at the primer terminus is the preferred substrate for the exonuclease activity over a correct basepair. The efficiency of the exonuclease as a proofreading activity for mispairs containing a DNA lesion varies, however, being dependent upon both the DNA polymerase/exonuclease and the type of DNA lesion. The exonuclease activities intrinsic to the T4 polymerase (family B) and DNA polymerase γ (family A) proofread DNA mispairs opposite endogenous DNA lesions, including alkylation, oxidation, and abasic adducts. However, the exonuclease of the Klenow polymerase cannot discriminate between correct and incorrect bases opposite alkylation and oxidative lesions. DNA damage alters the dynamics of the intramolecular partitioning of DNA substrates between the 3'→5' exonuclease and polymerase activities. Enzymatic idling at lesions occurs when an exonuclease activity efficiently removes the same base that is preferentially incorporated by the DNA polymerase activity. Thus, the exonuclease activity can also act as a kinetic barrier to translesion synthesis (TLS) by preventing the stable incorporation of bases opposite DNA lesions. Understanding the downstream consequences of exonuclease activity at DNA lesions is necessary for elucidating the mechanisms of translesion synthesis and damage-induced cytotoxicity

  15. Structural Transformation of Wireframe DNA Origami via DNA Polymerase Assisted Gap-Filling.

    Science.gov (United States)

    Agarwal, Nayan P; Matthies, Michael; Joffroy, Bastian; Schmidt, Thorsten L

    2018-03-27

    The programmability of DNA enables constructing nanostructures with almost any arbitrary shape, which can be decorated with many functional materials. Moreover, dynamic structures can be realized such as molecular motors and walkers. In this work, we have explored the possibility to synthesize the complementary sequences to single-stranded gap regions in the DNA origami scaffold cost effectively by a DNA polymerase rather than by a DNA synthesizer. For this purpose, four different wireframe DNA origami structures were designed to have single-stranded gap regions. This reduced the number of staple strands needed to determine the shape and size of the final structure after gap filling. For this, several DNA polymerases and single-stranded binding (SSB) proteins were tested, with T4 DNA polymerase being the best fit. The structures could be folded in as little as 6 min, and the subsequent optimized gap-filling reaction was completed in less than 3 min. The introduction of flexible gap regions results in fully collapsed or partially bent structures due to entropic spring effects. Finally, we demonstrated structural transformations of such deformed wireframe DNA origami structures with DNA polymerases including the expansion of collapsed structures and the straightening of curved tubes. We anticipate that this approach will become a powerful tool to build DNA wireframe structures more material-efficiently, and to quickly prototype and test new wireframe designs that can be expanded, rigidified, or mechanically switched. Mechanical force generation and structural transitions will enable applications in structural DNA nanotechnology, plasmonics, or single-molecule biophysics.

  16. DNA polymerase I is required for premeiotic DNA replication and sporulation but not for X-ray repair in Saccharomyces cerevisiae

    International Nuclear Information System (INIS)

    Budd, M.E.; Wittrup, K.D.; Bailey, J.E.; Campbell, J.L.

    1989-01-01

    We have used a set of seven temperature-sensitive mutants in the DNA polymerase I gene of Saccharomyces cerevisiae to investigate the role of DNA polymerase I in various aspects of DNA synthesis in vivo. Previously, we showed that DNA polymerase I is required for mitotic DNA replication. Here we extend our studies to several stages of meiosis and repair of X-ray-induced damage. We find that sporulation is blocked in all of the DNA polymerase temperature-sensitive mutants and that premeiotic DNA replication does not occur. Commitment to meiotic recombination is only 2% of wild-type levels. Thus, DNA polymerase I is essential for these steps. However, repair of X-ray-induced single-strand breaks is not defective in the DNA polymerase temperature-sensitive mutants, and DNA polymerase I is therefore not essential for repair of such lesions. These results suggest that DNA polymerase II or III or both, the two other nuclear yeast DNA polymerases for which roles have not yet been established, carry out repair in the absence of DNA polymerase I, but that DNA polymerase II and III cannot compensate for loss of DNA polymerase I in meiotic replication and recombination. These results do not, however, rule out essential roles for DNA polymerase II or III or both in addition to that for DNA polymerase I

  17. Crystal structure of DNA polymerase III β sliding clamp from Mycobacterium tuberculosis.

    Science.gov (United States)

    Gui, Wen-Jun; Lin, Shi-Qiang; Chen, Yuan-Yuan; Zhang, Xian-En; Bi, Li-Jun; Jiang, Tao

    2011-02-11

    The sliding clamp is a key component of DNA polymerase III (Pol III) required for genome replication. It is known to function with diverse DNA repair proteins and cell cycle-control proteins, making it a potential drug target. To extend our understanding of the structure/function relationship of the sliding clamp, we solved the crystal structure of the sliding clamp from Mycobacterium tuberculosis (M. tuberculosis), a human pathogen that causes most cases of tuberculosis (TB). The sliding clamp from M. tuberculosis forms a ring-shaped head-to-tail dimer with three domains per subunit. Each domain contains two α helices in the inner ring that lie against two β sheets in the outer ring. Previous studies have indicated that many Escherichia coli clamp-binding proteins have a conserved LF sequence, which is critical for binding to the hydrophobic region of the sliding clamp. Here, we analyzed the binding affinities of the M. tuberculosis sliding clamp and peptides derived from the α and δ subunits of Pol III, which indicated that the LF motif also plays an important role in the binding of the α and δ subunits to the sliding clamp of M. tuberculosis. Copyright © 2011 Elsevier Inc. All rights reserved.

  18. Excess Polθ functions in response to replicative stress in homologous recombination-proficient cancer cells

    Directory of Open Access Journals (Sweden)

    T. Goullet de Rugy

    2016-10-01

    Full Text Available DNA polymerase theta (Polθ is a specialized A-family DNA polymerase that functions in processes such as translesion synthesis (TLS, DNA double-strand break repair and DNA replication timing. Overexpression of POLQ, the gene encoding Polθ, is a prognostic marker for an adverse outcome in a wide range of human cancers. While increased Polθ dosage was recently suggested to promote survival of homologous recombination (HR-deficient cancer cells, it remains unclear whether POLQ overexpression could be also beneficial to HR-proficient cancer cells. By performing a short interfering (siRNA screen in which genes encoding druggable proteins were knocked down in Polθ-overexpressing cells as a means to uncover genetic vulnerabilities associated with POLQ overexpression, we could not identify genes that were essential for viability in Polθ-overexpressing cells in normal growth conditions. We also showed that, upon external DNA replication stress, Polθ expression promotes cell survival and limits genetic instability. Finally, we report that POLQ expression correlates with the expression of a set of HR genes in breast, lung and colorectal cancers. Collectively, our data suggest that Polθ upregulation, besides its importance for survival of HR-deficient cancer cells, may be crucial also for HR-proficient cells to better tolerate DNA replication stress, as part of a global gene deregulation response, including HR genes.

  19. Fusion of Taq DNA polymerase with single-stranded DNA binding-like protein of Nanoarchaeum equitans-Expression and characterization.

    Directory of Open Access Journals (Sweden)

    Marcin Olszewski

    Full Text Available DNA polymerases are present in all organisms and are important enzymes that synthesise DNA molecules. They are used in various fields of science, predominantly as essential components for in vitro DNA syntheses, known as PCR. Modern diagnostics, molecular biology and genetic engineering need DNA polymerases which demonstrate improved performance. This study was aimed at obtaining a new NeqSSB-TaqS fusion DNA polymerase from the Taq DNA Stoffel domain and a single-stranded DNA binding-like protein of Nanoarchaeum equitans in order to significantly improve the properties of DNA polymerase. The DNA coding sequence of Taq Stoffel DNA polymerase and the nonspecific DNA-binding protein of Nanoarchaeum equitans (NeqSSB-like protein were fused. A novel recombinant gene was obtained which was cloned into the pET-30 Ek/LIC vector and introduced into E. coli for expression. The recombinant enzyme was purified and its enzymatic properties including DNA polymerase activity, PCR amplification rate, thermostability, processivity and resistance to inhibitors, were tested. The yield of the target protein reached approximately 18 mg/l after 24 h of the IPTG induction. The specific activity of the polymerase was 2200 U/mg. The recombinant NeqSSB-TaqS exhibited a much higher extension rate (1000 bp template in 20 s, processivity (19 nt, thermostability (half-life 35 min at 95°C and higher tolerance to PCR inhibitors (0.3-1.25% of whole blood, 0.84-13.5 μg of lactoferrin and 4.7-150 ng of heparin than Taq Stoffel DNA polymerase. Furthermore, our studies show that NeqSSB-TaqS DNA polymerase has a high level of flexibility in relation to Mg2+ ions (from 1 to 5 mM and KCl or (NH42SO4 salts (more than 60 mM and 40 mM, respectively. Using NeqSSB-TaqS DNA polymerase instead of the Taq DNA polymerase could be a better choice in many PCR applications.

  20. Accurate Digital Polymerase Chain Reaction Quantification of Challenging Samples Applying Inhibitor-Tolerant DNA Polymerases.

    Science.gov (United States)

    Sidstedt, Maja; Romsos, Erica L; Hedell, Ronny; Ansell, Ricky; Steffen, Carolyn R; Vallone, Peter M; Rådström, Peter; Hedman, Johannes

    2017-02-07

    Digital PCR (dPCR) enables absolute quantification of nucleic acids by partitioning of the sample into hundreds or thousands of minute reactions. By assuming a Poisson distribution for the number of DNA fragments present in each chamber, the DNA concentration is determined without the need for a standard curve. However, when analyzing nucleic acids from complex matrixes such as soil and blood, the dPCR quantification can be biased due to the presence of inhibitory compounds. In this study, we evaluated the impact of varying the DNA polymerase in chamber-based dPCR for both pure and impure samples using the common PCR inhibitor humic acid (HA) as a model. We compared the TaqMan Universal PCR Master Mix with two alternative DNA polymerases: ExTaq HS and Immolase. By using Bayesian modeling, we show that there is no difference among the tested DNA polymerases in terms of accuracy of absolute quantification for pure template samples, i.e., without HA present. For samples containing HA, there were great differences in performance: the TaqMan Universal PCR Master Mix failed to correctly quantify DNA with more than 13 pg/nL HA, whereas Immolase (1 U) could handle up to 375 pg/nL HA. Furthermore, we found that BSA had a moderate positive effect for the TaqMan Universal PCR Master Mix, enabling accurate quantification for 25 pg/nL HA. Increasing the amount of DNA polymerase from 1 to 5 U had a strong effect for ExTaq HS, elevating HA-tolerance four times. We also show that the average Cq values of positive reactions may be used as a measure of inhibition effects, e.g., to determine whether or not a dPCR quantification result is reliable. The statistical models developed to objectively analyze the data may also be applied in quality control. We conclude that the choice of DNA polymerase in dPCR is crucial for the accuracy of quantification when analyzing challenging samples.

  1. InterProScan Result: FS758275 [KAIKOcDNA[Archive

    Lifescience Database Archive (English)

    Full Text Available FS758275 FS758275_1_ORF2 2EC8961369A7A64F PANTHER PTHR11064:SF10 DNA POLYMERASE EPSILON P17 SUBUNIT (DNA POL...YMERASE EPSILON SUBUNIT 3) NA ? IPR009072 unintegrated Molecular Function: DNA binding (GO:0003677) ...

  2. InterProScan Result: FS827626 [KAIKOcDNA[Archive

    Lifescience Database Archive (English)

    Full Text Available FS827626 FS827626_6_ORF2 2EC8961369A7A64F PANTHER PTHR11064:SF10 DNA POLYMERASE EPSILON P17 SUBUNIT (DNA POL...YMERASE EPSILON SUBUNIT 3) NA ? IPR009072 unintegrated Molecular Function: DNA binding (GO:0003677) ...

  3. Catalytic properties of RNA polymerases IV and V: accuracy, nucleotide incorporation and rNTP/dNTP discrimination.

    Science.gov (United States)

    Marasco, Michelle; Li, Weiyi; Lynch, Michael; Pikaard, Craig S

    2017-11-02

    All eukaryotes have three essential nuclear multisubunit RNA polymerases, abbreviated as Pol I, Pol II and Pol III. Plants are remarkable in having two additional multisubunit RNA polymerases, Pol IV and Pol V, which synthesize noncoding RNAs that coordinate RNA-directed DNA methylation for silencing of transposons and a subset of genes. Based on their subunit compositions, Pols IV and V clearly evolved as specialized forms of Pol II, but their catalytic properties remain undefined. Here, we show that Pols IV and V differ from one another, and Pol II, in nucleotide incorporation rate, transcriptional accuracy and the ability to discriminate between ribonucleotides and deoxyribonucleotides. Pol IV transcription is considerably more error-prone than Pols II or V, which may be tolerable in its synthesis of short RNAs that serve as precursors for siRNAs targeting non-identical members of transposon families. By contrast, Pol V exhibits high fidelity transcription, similar to Pol II, suggesting a need for Pol V transcripts to faithfully reflect the DNA sequence of target loci to which siRNA-Argonaute silencing complexes are recruited. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

  4. HeLa Cells Containing a Truncated Form of DNA Polymerase Beta are More Sensitized to Alkylating Agents than to Agents Inducing Oxidative Stress.

    Science.gov (United States)

    Khanra, Kalyani; Chakraborty, Anindita; Bhattacharyya, Nandan

    2015-01-01

    The present study was aimed at determining the effects of alkylating and oxidative stress inducing agents on a newly identified variant of DNA polymerase beta (polβ Δ208-304) specific for ovarian cancer. Pol β Δ208-304 has a deletion of exons 11-13 which lie in the catalytic part of enzyme. We compared the effect of these chemicals on HeLa cells and HeLa cells stably transfected with this variant cloned into in pcDNAI/neo vector by MTT, colony forming and apoptosis assays. Polβ Δ208-304 cells exhibited greater sensitivity to an alkylating agent and less sensitivity towards H2O2 and UV when compared with HeLa cells alone. It has been shown that cell death in Pol β Δ208-304 transfected HeLa cells is mediated by the caspase 9 cascade. Exon 11 has nucleotidyl selection activity, while exons 12 and 13 have dNTP selection activity. Hence deletion of this part may affect polymerizing activity although single strand binding and double strand binding activity may remain same. The lack of this part may adversely affect catalytic activity of DNA polymerase beta so that the variant may act as a dominant negative mutant. This would represent clinical significance if translated into a clinical setting because resistance to radiation or chemotherapy during the relapse of the disease could be potentially overcome by this approach.

  5. The essential DNA polymerases δ and ε are involved in repair of UV-damaged DNA in the yeast Saccharomyces cerevisiae

    International Nuclear Information System (INIS)

    Halas, A.; Policinska, Z.; Baranowska, H.; Jachymczyk, W.J.

    1999-01-01

    We have studied the ability of yeast DNA polymerases to carry out repair of lesions caused by UV irradiation in Saccharomyces cerevisiae. By the analysis of postirradiation relative molecular mass changes in cellular DNA of different DNA polymerases mutant strains, it was established that mutations in DNA polymerases δ and ε showed accumulation of single-strand breaks indicating defective repair. Mutations in other DNA polymerase genes exhibited no defects in DNA repair. Thus, the data obtained suggest that DNA polymerases δ and ε are both necessary for DNA replication and for repair of lesions caused by UV irradiation. The results are discussed in the light of current concepts concerning the specificity of DNA polymerases in DNA repair. (author)

  6. Modulation of DNA polymerase beta-dependent base excision repair in cultured human cells after low dose exposure to arsenite

    International Nuclear Information System (INIS)

    Sykora, Peter; Snow, Elizabeth T.

    2008-01-01

    Base excision repair (BER) is crucial for development and for the repair of endogenous DNA damage. However, unlike nucleotide excision repair, the regulation of BER is not well understood. Arsenic, a well-established human carcinogen, is known to produce oxidative DNA damage, which is repaired primarily by BER, whilst high doses of arsenic can also inhibit DNA repair. However, the mechanism of repair inhibition by arsenic and the steps inhibited are not well defined. To address this question we have investigated the regulation of DNA polymerase β (Pol β) and AP endonuclease (APE1), in response to low, physiologically relevant doses of arsenic. GM847 lung fibroblasts and HaCaT keratinocytes were exposed to sodium arsenite, As(III), and mRNA, protein levels and BER activity were assessed. Both Pol β and APE1 mRNA exhibited significant dose-dependant down regulation at doses of As(III) above 1 μM. However, at lower doses Pol β mRNA and protein levels, and consequently, BER activity were significantly increased. In contrast, APE1 protein levels were only marginally increased by low doses of As(III) and there was no correlation between APE1 and overall BER activity. Enzyme supplementation of nuclear extracts confirmed that Pol β was rate limiting. These changes in BER correlated with overall protection against sunlight UV-induced toxicity at low doses of As(III) and produced synergistic toxicity at high doses. The results provide evidence that changes in BER due to low doses of arsenic could contribute to a non-linear, threshold dose response for arsenic carcinogenesis

  7. Involvement of DNA polymerase δ in DNA repair synthesis in human fibroblasts at late times after ultraviolet irradiation

    International Nuclear Information System (INIS)

    Dresler, S.L.; Gowans, B.J.; Robinson-Hill, R.M.; Hunting, D.J.

    1988-01-01

    DNA repair synthesis following UV irradiation of confluent human fibroblasts has a biphasic time course with an early phase of rapid nucleotide incorporation and a late phase of much slower nucleotide incorporation. The biphasic nature of this curve suggests that two distinct DNA repair systems may be operative. Previous studies have specifically implicated DNA polymerase δ as the enzyme involved in DNA repair synthesis occurring immediately after UV damage. In this paper, the authors describe studies of DNA polymerase involvement in DNA repair synthesis in confluent human fibroblasts at late times after UV irradiation. Late UV-induced DNA repair synthesis in both intact and permeable cells was found to be inhibited by aphidicolin, indicating the involvement of one of the aphidicolin-sensitive DNA polymerases, α or δ. In permeable cells, the process was further analyzed by using the nucleotide analogue (butylphenyl)-2'-deoxyguanosine 5'-triphosphate, which inhibits DNA polymerase α several hundred times more strongly than it inhibits DNA polymerase δ. The (butylphenyl)-2'-deoxyguanosine 5'-triphosphate inhibition curve for late UV-induced repair synthesis was very similar to that for polymerase δ. It appears that repair synthesis at late time after UV irradiation, like repair synthesis at early times, is mediated by DNA polymerase δ

  8. DNA polymerase β decrement triggers death of olfactory bulb cells and impairs olfaction in a mouse model of Alzheimer's disease.

    Science.gov (United States)

    Misiak, Magdalena; Vergara Greeno, Rebeca; Baptiste, Beverly A; Sykora, Peter; Liu, Dong; Cordonnier, Stephanie; Fang, Evandro F; Croteau, Deborah L; Mattson, Mark P; Bohr, Vilhelm A

    2017-02-01

    Alzheimer's disease (AD) involves the progressive degeneration of neurons critical for learning and memory. In addition, patients with AD typically exhibit impaired olfaction associated with neuronal degeneration in the olfactory bulb (OB). Because DNA base excision repair (BER) is reduced in brain cells during normal aging and AD, we determined whether inefficient BER due to reduced DNA polymerase-β (Polβ) levels renders OB neurons vulnerable to degeneration in the 3xTgAD mouse model of AD. We interrogated OB histopathology and olfactory function in wild-type and 3xTgAD mice with normal or reduced Polβ levels. Compared to wild-type control mice, Polβ heterozygous (Polβ +/- ), and 3xTgAD mice, 3xTgAD/Polβ +/- mice exhibited impaired performance in a buried food test of olfaction. Polβ deficiency did not affect the proliferation of OB neural progenitor cells in the subventricular zone. However, numbers of newly generated neurons were reduced by approximately 25% in Polβ +/- and 3xTgAD mice, and by over 60% in the 3xTgAD/Polβ +/- mice compared to wild-type control mice. Analyses of DNA damage and apoptosis revealed significantly greater degeneration of OB neurons in 3xTgAD/Polβ +/- mice compared to 3xTgAD mice. Levels of amyloid β-peptide (Aβ) accumulation in the OB were similar in 3xTgAD and 3xTgAD/Polβ +/- mice, and cultured Polβ-deficient neurons exhibited increased vulnerability to Aβ-induced death. Olfactory deficit is an early sign in human AD, but the mechanism is not yet understood. Our findings in a new AD mouse model demonstrate that diminution of BER can endanger OB neurons, and suggest a mechanism underlying early olfactory impairment in AD. © 2016 The Authors. Aging Cell published by the Anatomical Society and John Wiley & Sons Ltd.

  9. Recent Insight into the Kinetic Mechanisms and Conformational Dynamics of Y-Family DNA Polymerases

    OpenAIRE

    Maxwell, Brian A.; Suo, Zucai

    2014-01-01

    The kinetic mechanisms by which DNA polymerases catalyze DNA replication and repair have long been areas of active research. Recently discovered Y-family DNA polymerases catalyze the bypass of damaged DNA bases that would otherwise block replicative DNA polymerases and stall replication forks. Unlike DNA polymerases from the five other families, the Y-family DNA polymerases have flexible, solvent-accessible active sites that are able to tolerate various types of damaged template bases and all...

  10. UVB DNA dosimeters analyzed by polymerase chain reactors

    International Nuclear Information System (INIS)

    Yoshida, Hiroko; Regan, J.D.; Florida Inst. of Tech., Melbourne, FL

    1997-01-01

    Purified bacteriophage λ DNA was dried on a UV-transparent polymer film and served as a UVB dosimeter for personal and ecological applications. Bacteriophage λ DNA was chosen because it is commercially available and inexpensive, and its entire sequence is known. Each dosimeter contained two sets of DNA sandwiched between UV-transparent polymer films, one exposed to solar radiation (experimental) and another protected from UV radiation by black paper (control). The DNA dosimeter was then analyzed by a polymerase chain reaction (PCR) that amplifies a 500 base pair specific region of λ DNA. Photoinduced damage in DNA blocks polymerase from synthesizing a new strand; therefore, the amount of amplified product in UV-exposed DNA was reduced from that found in control DNA. The dried λ DNA dosimeter is compact, robust, safe and transportable, stable over long storage times and provides the total UVB dose integrated over the exposure time. (author)

  11. DNA polymerases in the rat pituitary gland. Effect of oestrogens and sulpiride.

    Science.gov (United States)

    Jahn, G A; Kalbermann, L E; Machiavelli, G; Szijan, I; Burdman, J A

    1980-06-01

    Changes in the activity of DNA polymerase and [3H]thymidine incorporation into the DNA of the anterior pituitary gland were studied in oestrogenized male and pregnant rats. The activities of DNA polymerases alpha and beta, extracted in Tris--HCl or in sodium phosphate buffer were characterized according to their optimum pH and sensitivity to N-ethyl-maleimide. In the Tris-soluble fraction DNA polymerase activity is almost exclusively alpha, while in the phosphate soluble fraction it is a mixture of alpha and beta. The administration of oestrogens to male rats increases [3H]thymidine incorporation and enhances the activity of DNA polymerases in the Tris-soluble fraction, while the activity of the phosphate-soluble enzyme does not change. Sulpiride administration results in a further increment of [3H]thymidine incorporation and of DNA polymerase activity in the Tris-soluble fraction. In pregnant rats sulpiride also produces an increment of DNA polymerase activity only in the Tris-soluble fraction. Thus, the activity of the Tris-soluble fraction from APG behaves as DNA polymerase alpha. This activity changes in parallel with [3H]thymidine incorporation into DNA which is an indication of cell proliferation in the gland. This is discussed with respect to a negative feedback mechanism between intracellular prolactin concentration and DNA synthesis in the APG.

  12. InterProScan Result: FS827626 [KAIKOcDNA[Archive

    Lifescience Database Archive (English)

    Full Text Available FS827626 FS827626_6_ORF2 2EC8961369A7A64F PANTHER PTHR11064:SF10 DNA POLYMERASE EPSILON P17 SUBUNIT (DNA POL...YMERASE EPSILON SUBUNIT 3) 9e-35 T IPR009072 unintegrated Molecular Function: DNA binding (GO:0003677) ...

  13. InterProScan Result: FS758275 [KAIKOcDNA[Archive

    Lifescience Database Archive (English)

    Full Text Available FS758275 FS758275_1_ORF2 2EC8961369A7A64F PANTHER PTHR11064:SF10 DNA POLYMERASE EPSILON P17 SUBUNIT (DNA POL...YMERASE EPSILON SUBUNIT 3) 9e-35 T IPR009072 unintegrated Molecular Function: DNA binding (GO:0003677) ...

  14. Characterization of Recombinant Thermococcus kodakaraensis (KOD) DNA Polymerases Produced Using Silkworm-Baculovirus Expression Vector System

    KAUST Repository

    Yamashita, Mami

    2017-05-08

    The KOD DNA polymerase from Thermococcus kodakarensis (Tkod-Pol) has been preferred for PCR due to its rapid elongation rate, extreme thermostability and outstanding fidelity. Here in this study, we utilized silkworm-baculovirus expression vector system (silkworm-BEVS) to express the recombinant Tkod-Pol (rKOD) with N-terminal (rKOD-N) or C-terminal (rKOD-C) tandem fusion tags. By using BEVS, we produced functional rKODs with satisfactory yields, about 1.1 mg/larva for rKOD-N and 0.25 mg/larva for rKOD-C, respectively. Interestingly, we found that rKOD-C shows higher thermostability at 95 °C than that of rKOD-N, while that rKOD-N is significantly unstable after exposing to long period of heat-shock. We also assessed the polymerase activity as well as the fidelity of purified rKODs under various conditions. Compared with commercially available rKOD, which is expressed in E. coli expression system, rKOD-C exhibited almost the same PCR performance as the commercial rKOD did, while rKOD-N did lower performance. Taken together, our results suggested that silkworm-BEVS can be used to express and purify efficient rKOD in a commercial way.

  15. Characterization of Recombinant Thermococcus kodakaraensis (KOD) DNA Polymerases Produced Using Silkworm-Baculovirus Expression Vector System

    KAUST Repository

    Yamashita, Mami; Xu, Jian; Morokuma, Daisuke; Hirata, Kazuma; Hino, Masato; Mon, Hiroaki; Takahashi, Masateru; Hamdan, Samir; Sakashita, Kosuke; Iiyama, Kazuhiro; Banno, Yutaka; Kusakabe, Takahiro; Lee, Jae Man

    2017-01-01

    The KOD DNA polymerase from Thermococcus kodakarensis (Tkod-Pol) has been preferred for PCR due to its rapid elongation rate, extreme thermostability and outstanding fidelity. Here in this study, we utilized silkworm-baculovirus expression vector system (silkworm-BEVS) to express the recombinant Tkod-Pol (rKOD) with N-terminal (rKOD-N) or C-terminal (rKOD-C) tandem fusion tags. By using BEVS, we produced functional rKODs with satisfactory yields, about 1.1 mg/larva for rKOD-N and 0.25 mg/larva for rKOD-C, respectively. Interestingly, we found that rKOD-C shows higher thermostability at 95 °C than that of rKOD-N, while that rKOD-N is significantly unstable after exposing to long period of heat-shock. We also assessed the polymerase activity as well as the fidelity of purified rKODs under various conditions. Compared with commercially available rKOD, which is expressed in E. coli expression system, rKOD-C exhibited almost the same PCR performance as the commercial rKOD did, while rKOD-N did lower performance. Taken together, our results suggested that silkworm-BEVS can be used to express and purify efficient rKOD in a commercial way.

  16. Phosphorylation of ETS-1 is a critical event in DNA polymerase iota-induced invasion and metastasis of esophageal squamous cell carcinoma.

    Science.gov (United States)

    He, Chao; Wu, Shuhua; Gao, Aidi; Su, Ye; Min, Han; Shang, Zeng-Fu; Wu, Jinchang; Yang, Li; Ding, Wei-Qun; Zhou, Jundong

    2017-12-01

    An aberrantly elevated expression of DNA polymerase ι (Pol ι) is significantly associated with poor prognosis of patients with esophageal squamous cell carcinoma (ESCC), yet the mechanisms behind this phenomenon remain obscure. Based on the RNA-Seq transcriptome and real-time PCR analysis, we identified ETS-1 as a candidate gene involved in Pol ι-mediated progression of ESCC. Wound-healing and transwell assay indicated that downregulation of ETS-1 attenuates Pol ι-mediated invasiveness of ESCC. Signaling pathway analysis showed that Pol ι enhances ETS-1 phosphorylation at threonine-38 through the Erk signaling pathway in ESCC cells. Kaplan-Meier analysis, based on 93 clinical tissue samples, revealed that ETS-1 phosphorylation at threonine-38 is associated with poor prognosis of ESCC patients. The present study thus demonstrates that phosphorylation of ETS-1 is a critical event in the Pol ι-induced invasion and metastasis of ESCC. © 2017 The Authors. Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.

  17. EBV DNA polymerase inhibition of tannins from Eugenia uniflora.

    Science.gov (United States)

    Lee, M H; Chiou, J F; Yen, K Y; Yang, L L

    2000-06-30

    Nasopharyngeal carcinoma (NPC) is one of the high population malignant tumors among Chinese in southern China and southeast Asia. Epstein-Barr virus (EBV) is a human B lymphotropic herpes virus which is known to be closely associated with NPC. EBV DNA polymerase is a key enzyme during EBV replication and is measured by its radioactivity. The addition of phorbol 12-myristate 13-acetate to Raji cell cultures led to a large increase in EBV DNA polymerase, which was purified by sequential DEAE-cellulose, phosphocellulose and DNA-cellulose column chromatography. Four tannins were isolated from the active fractions of Eugenia uniflora L., which were tested for the inhibition of EBV DNA polymerase. The results showed the 50% inhibitory concentration (IC(50)) values of gallocatechin, oenothein B, eugeniflorins D(1) and D(2) were 26.5 62.3, 3.0 and 3.5 microM, respectively. Furthermore, when compared with the positive control (phosphonoacetic acid), an inhibitor of EBV replication, the IC(50) value was 16.4 microM. In view of the results, eugeniflorins D(1) and D(2) are the potency principles in the inhibition of EBV DNA polymerase from E. uniflora.

  18. A domain of the Klenow fragment of Escherichia coli DNA polymerase I has polymerase but no exonuclease activity.

    Science.gov (United States)

    Freemont, P S; Ollis, D L; Steitz, T A; Joyce, C M

    1986-09-01

    The Klenow fragment of DNA polymerase I from Escherichia coli has two enzymatic activities: DNA polymerase and 3'-5' exonuclease. The crystal structure showed that the fragment is folded into two distinct domains. The smaller domain has a binding site for deoxynucleoside monophosphate and a divalent metal ion that is thought to identify the 3'-5' exonuclease active site. The larger C-terminal domain contains a deep cleft that is believed to bind duplex DNA. Several lines of evidence suggested that the large domain also contains the polymerase active site. To test this hypothesis, we have cloned the DNA coding for the large domain into an expression system and purified the protein product. We find that the C-terminal domain has polymerase activity (albeit at a lower specific activity than the native Klenow fragment) but no measurable 3'-5' exonuclease activity. These data are consistent with the hypothesis that each of the three enzymatic activities of DNA polymerase I from E. coli resides on a separate protein structural domain.

  19. DNA polymerase I-mediated ultraviolet repair synthesis in toluene-treated Escherichia coli

    International Nuclear Information System (INIS)

    Dorson, J.W.; Moses, R.E.

    1978-01-01

    DNA synthesis after ultraviolet irradiation is low in wild type toluene-treated cells. The level of repair incorporation is greater in strains deficient in DNA polymerase I. The low level of repair synthesis is attributable to the concerted action of DNA polymerase I and polynucleotide ligase. Repair synthesis is stimulated by blocking ligase activity with the addition of nicotinamide mononucleotide (NMN) or the use of a ligase temperature-sensitive mutant. NMN stimulation is specific for DNA polymerase I-mediated repair synthesis, as it is absent in isogenic strains deficient in the polymerase function or the 5' yields 3' exonuclease function associated with DNA polymerase I. DNA synthesis that is stimulated by NMN is proportional to the ultraviolet exposure at low doses, nonconservative in nature, and is dependent on the uvrA gene product but is independent of the recA gene product. These criteria place this synthesis in the excision repair pathway. The NMN-stimulated repair synthesis requires ATP and is N-ethylmaleimide-resistant. The use of NMN provides a direct means for evaluating the involvement of DNA polymerase I in excision repair

  20. Analysis of DNA polymerase activity in Petunia protoplasts treated with clastogenic agents

    International Nuclear Information System (INIS)

    Benediktsson, I.; Spampinato, C.P.; Andreo, C.S.; Schieder, O.

    1994-01-01

    Clastogenic agents, i.e. agents that can induce chromosome or DNA breakage, have been shown to enhance the role of direct gene transfer to protoplasts. The effect was analysed at the enzymatic level using protoplast homogenates as well as intact protoplasts. For that purpose existing procedures were modified to enable measurement of DNA polymerase in vivo. In the system used, external DNA was able to enter the cells without the addition of membrane-permeabilizing compounds. When comparing total DNA polymerase activity of protoplasts irradiated with X-rays or UV-light with that of untreated cells we did not observe significant differences. Incubation of protoplasts with high doses of bleomycin affected total DNA polymerase activity negatively. but dideoxythymidine triphosphate-sensitive activity was not influenced. We conclude that the DNA strand-breaks induced by low doses of X-rays. UV-light or bleomycin do not increase the total or the repair-DNA polymerase activity and. therefore. that the increase in the transformation rates after DNA strand-breaking is not preceded by enhanced DNA polymerase activity. (author)

  1. NSC666715 and Its Analogs Inhibit Strand-Displacement Activity of DNA Polymerase β and Potentiate Temozolomide-Induced DNA Damage, Senescence and Apoptosis in Colorectal Cancer Cells.

    Directory of Open Access Journals (Sweden)

    Aruna S Jaiswal

    Full Text Available Recently approved chemotherapeutic agents to treat colorectal cancer (CRC have made some impact; however, there is an urgent need for newer targeted agents and strategies to circumvent CRC growth and metastasis. CRC frequently exhibits natural resistance to chemotherapy and those who do respond initially later acquire drug resistance. A mechanism to potentially sensitize CRC cells is by blocking the DNA polymerase β (Pol-β activity. Temozolomide (TMZ, an alkylating agent, and other DNA-interacting agents exert DNA damage primarily repaired by a Pol-β-directed base excision repair (BER pathway. In previous studies, we used structure-based molecular docking of Pol-β and identified a potent small molecule inhibitor (NSC666715. In the present study, we have determined the mechanism by which NSC666715 and its analogs block Fen1-induced strand-displacement activity of Pol-β-directed LP-BER, cause apurinic/apyrimidinic (AP site accumulation and induce S-phase cell cycle arrest. Induction of S-phase cell cycle arrest leads to senescence and apoptosis of CRC cells through the p53/p21 pathway. Our initial findings also show a 10-fold reduction of the IC50 of TMZ when combined with NSC666715. These results provide a guide for the development of a target-defined strategy for CRC chemotherapy that will be based on the mechanisms of action of NSC666715 and TMZ. This combination strategy can be used as a framework to further reduce the TMZ dosages and resistance in CRC patients.

  2. DNA Polymerase α (swi7) and the Flap Endonuclease Fen1 (rad2) Act Together in the S-Phase Alkylation Damage Response in S. pombe

    Science.gov (United States)

    Koulintchenko, Milana; Vengrova, Sonya; Eydmann, Trevor; Arumugam, Prakash; Dalgaard, Jacob Z.

    2012-01-01

    Polymerase α is an essential enzyme mainly mediating Okazaki fragment synthesis during lagging strand replication. A specific point mutation in Schizosaccharomyces pombe polymerase α named swi7-1, abolishes imprinting required for mating-type switching. Here we investigate whether this mutation confers any genome-wide defects. We show that the swi7-1 mutation renders cells hypersensitive to the DNA damaging agents methyl methansulfonate (MMS), hydroxyurea (HU) and UV and incapacitates activation of the intra-S checkpoint in response to DNA damage. In addition we show that, in the swi7-1 background, cells are characterized by an elevated level of repair foci and recombination, indicative of increased genetic instability. Furthermore, we detect novel Swi1-, -Swi3- and Pol α- dependent alkylation damage repair intermediates with mobility on 2D-gel that suggests presence of single-stranded regions. Genetic interaction studies showed that the flap endonuclease Fen1 works in the same pathway as Pol α in terms of alkylation damage response. Fen1 was also required for formation of alkylation- damage specific repair intermediates. We propose a model to explain how Pol α, Swi1, Swi3 and Fen1 might act together to detect and repair alkylation damage during S-phase. PMID:23071723

  3. Estrogen Drives Cellular Transformation and Mutagenesis in Cells Expressing the Breast Cancer-Associated R438W DNA Polymerase Lambda Protein.

    Science.gov (United States)

    Nemec, Antonia A; Bush, Korie B; Towle-Weicksel, Jamie B; Taylor, B Frazier; Schulz, Vincent; Weidhaas, Joanne B; Tuck, David P; Sweasy, Joann B

    2016-11-01

    Repair of DNA damage is critical for maintaining the genomic integrity of cells. DNA polymerase lambda (POLL/Pol λ) is suggested to function in base excision repair (BER) and nonhomologous end-joining (NHEJ), and is likely to play a role in damage tolerance at the replication fork. Here, using next-generation sequencing, it was discovered that the POLL rs3730477 single-nucleotide polymorphism (SNP) encoding R438W Pol λ was significantly enriched in the germlines of breast cancer patients. Expression of R438W Pol λ in human breast epithelial cells induces cellular transformation and chromosomal aberrations. The role of estrogen was assessed as it is commonly used in hormone replacement therapies and is a known breast cancer risk factor. Interestingly, the combination of estrogen treatment and the expression of the R438W Pol λ SNP drastically accelerated the rate of transformation. Estrogen exposure produces 8-oxoguanine lesions that persist in cells expressing R438W Pol λ compared with wild-type (WT) Pol λ-expressing cells. Unlike WT Pol λ, which performs error-free bypass of 8-oxoguanine lesions, expression of R438W Pol λ leads to an increase in mutagenesis and replicative stress in cells treated with estrogen. Together, these data suggest that individuals who carry the rs3730477 POLL germline variant have an increased risk of estrogen-associated breast cancer. The Pol λ R438W mutation can serve as a biomarker to predict cancer risk and implicates that treatment with estrogen in individuals with this mutation may further increase their risk of breast cancer. Mol Cancer Res; 14(11); 1068-77. ©2016 AACR. ©2016 American Association for Cancer Research.

  4. Architecture of the RNA polymerase II-Mediator core initiation complex.

    Science.gov (United States)

    Plaschka, C; Larivière, L; Wenzeck, L; Seizl, M; Hemann, M; Tegunov, D; Petrotchenko, E V; Borchers, C H; Baumeister, W; Herzog, F; Villa, E; Cramer, P

    2015-02-19

    The conserved co-activator complex Mediator enables regulated transcription initiation by RNA polymerase (Pol) II. Here we reconstitute an active 15-subunit core Mediator (cMed) comprising all essential Mediator subunits from Saccharomyces cerevisiae. The cryo-electron microscopic structure of cMed bound to a core initiation complex was determined at 9.7 Å resolution. cMed binds Pol II around the Rpb4-Rpb7 stalk near the carboxy-terminal domain (CTD). The Mediator head module binds the Pol II dock and the TFIIB ribbon and stabilizes the initiation complex. The Mediator middle module extends to the Pol II foot with a 'plank' that may influence polymerase conformation. The Mediator subunit Med14 forms a 'beam' between the head and middle modules and connects to the tail module that is predicted to bind transcription activators located on upstream DNA. The Mediator 'arm' and 'hook' domains contribute to a 'cradle' that may position the CTD and TFIIH kinase to stimulate Pol II phosphorylation.

  5. A polymerase chain reaction strategy for the diagnosis of camelpox.

    Science.gov (United States)

    Balamurugan, Vinayagamurthy; Bhanuprakash, Veerakyathappa; Hosamani, Madhusudhan; Jayappa, Kallesh Danappa; Venkatesan, Gnanavel; Chauhan, Bina; Singh, Raj Kumar

    2009-03-01

    Camelpox is a contagious viral skin disease that is mostly seen in young camels. The disease is caused by the Camelpox virus (CMLV). In the present study, a polymerase chain reaction (PCR) assay based on the C18L gene (encoding ankyrin repeat protein) and a duplex PCR based on the C18L and DNA polymerase (DNA pol) genes were developed. The former assay yields a specific amplicon of 243 bp of the C18L gene, whereas the duplex PCR yields 243- and 96-bp products of the C18L and DNA pol genes, respectively, in CMLV, and only a 96-bp product of the DNA pol gene in other orthopoxviruses. The limit of detection was as low as 0.4 ng of viral DNA. Both PCR assays were employed successfully for the direct detection and differentiation of CMLV from other orthopoxviruses, capripoxviruses, and parapoxviruses in both cell culture samples and clinical material. Furthermore, a highly sensitive SYBR Green dye-based, real-time PCR was optimized for quantitation of CMLV DNA. In the standard curve of the quantitative assay, the melting temperature of the specific amplicon at 77.6 degrees C with peak measured fluorescence in dissociation plot was observed with an efficiency of 102%. To the authors' knowledge, this is the first report to describe a C18L gene-based PCR for specific diagnosis of camelpox infection.

  6. Global conformational dynamics of a Y-family DNA polymerase during catalysis.

    Directory of Open Access Journals (Sweden)

    Cuiling Xu

    2009-10-01

    Full Text Available Replicative DNA polymerases are stalled by damaged DNA while the newly discovered Y-family DNA polymerases are recruited to rescue these stalled replication forks, thereby enhancing cell survival. The Y-family DNA polymerases, characterized by low fidelity and processivity, are able to bypass different classes of DNA lesions. A variety of kinetic and structural studies have established a minimal reaction pathway common to all DNA polymerases, although the conformational intermediates are not well defined. Furthermore, the identification of the rate-limiting step of nucleotide incorporation catalyzed by any DNA polymerase has been a matter of long debate. By monitoring time-dependent fluorescence resonance energy transfer (FRET signal changes at multiple sites in each domain and DNA during catalysis, we present here a real-time picture of the global conformational transitions of a model Y-family enzyme: DNA polymerase IV (Dpo4 from Sulfolobus solfataricus. Our results provide evidence for a hypothetical DNA translocation event followed by a rapid protein conformational change prior to catalysis and a subsequent slow, post-chemistry protein conformational change. Surprisingly, the DNA translocation step was induced by the binding of a correct nucleotide. Moreover, we have determined the directions, rates, and activation energy barriers of the protein conformational transitions, which indicated that the four domains of Dpo4 moved in a synchronized manner. These results showed conclusively that a pre-chemistry conformational change associated with domain movements was too fast to be the rate-limiting step. Rather, the rearrangement of active site residues limited the rate of correct nucleotide incorporation. Collectively, the conformational dynamics of Dpo4 offer insights into how the inter-domain movements are related to enzymatic function and their concerted interactions with other proteins at the replication fork.

  7. Polymerase study: Improved detection of Salmonella and Campylobacter through the optimized use of DNA polymerases in diagnostic real-time PCR

    DEFF Research Database (Denmark)

    Søndergaard, Mette Sofie Rousing; Löfström, Charlotta; Al-Habib, Zahra Fares Sayer

    DNA extractions and intermediate or bad with the crude extractions, while TaKaRa ExTaq HS only performed well with the purest extractions of fecal samples and intermediate with semi-automated magnetic beads based extracted fecal samples. In conclusion, our data shows that exchanging the DNA polymerase......Diagnostic analyses of foodborne pathogens are increasingly based on molecular methods such as PCR, which can improve the sensitivity and reduce the analysis time. The core of PCR is the enzyme performing the reaction: the DNA polymerase. Changing the polymerase can influence the sensitivity...... commercially available polymerases and four master mixes in two validated PCR assays, for Campylobacter and Salmonella, respectively, to develop more sensitive, robust and cost effective assays. The polymerases were screened on purified DNA and the five best performing, for each PCR assay, were then applied...

  8. The spontaneous replication error and the mismatch discrimination mechanisms of human DNA polymerase β

    Science.gov (United States)

    Koag, Myong-Chul; Nam, Kwangho; Lee, Seongmin

    2014-01-01

    To provide molecular-level insights into the spontaneous replication error and the mismatch discrimination mechanisms of human DNA polymerase β (polβ), we report four crystal structures of polβ complexed with dG•dTTP and dA•dCTP mismatches in the presence of Mg2+ or Mn2+. The Mg2+-bound ground-state structures show that the dA•dCTP-Mg2+ complex adopts an ‘intermediate’ protein conformation while the dG•dTTP-Mg2+ complex adopts an open protein conformation. The Mn2+-bound ‘pre-chemistry-state’ structures show that the dA•dCTP-Mn2+ complex is structurally very similar to the dA•dCTP-Mg2+ complex, whereas the dG•dTTP-Mn2+ complex undergoes a large-scale conformational change to adopt a Watson–Crick-like dG•dTTP base pair and a closed protein conformation. These structural differences, together with our molecular dynamics simulation studies, suggest that polβ increases replication fidelity via a two-stage mismatch discrimination mechanism, where one is in the ground state and the other in the closed conformation state. In the closed conformation state, polβ appears to allow only a Watson–Crick-like conformation for purine•pyrimidine base pairs, thereby discriminating the mismatched base pairs based on their ability to form the Watson–Crick-like conformation. Overall, the present studies provide new insights into the spontaneous replication error and the replication fidelity mechanisms of polβ. PMID:25200079

  9. Nature of the Nucleosomal Barrier to RNA Polymerase II | Center for Cancer Research

    Science.gov (United States)

    In the cell, RNA polymerase II (pol II) efficiently transcribes DNA packaged into nucleosomes, but in vitro encounters with the nucleosomes induce catalytic inactivation (arrest) of the pol II core enzyme. To determine potential mechanisms making nucleosomes transparent to transcription in vivo, we analyzed the nature of the nucleosome-induced arrest. We found that the arrests

  10. Mutations of mtDNA polymerase-γ and hyperlactataemia in the HIV ...

    African Journals Online (AJOL)

    Mutations of mtDNA polymerase-γ and hyperlactataemia in the HIV-infected Zulu population of South Africa. ... D B A Ojwach, C Aldous, P Kocheleff, B Sartorius ... of their capacity to impede human mitochondrial DNA polymerase-γ (POLG), ...

  11. Competition between replicative and translesion polymerases during homologous recombination repair in Drosophila.

    Directory of Open Access Journals (Sweden)

    Daniel P Kane

    Full Text Available In metazoans, the mechanism by which DNA is synthesized during homologous recombination repair of double-strand breaks is poorly understood. Specifically, the identities of the polymerase(s that carry out repair synthesis and how they are recruited to repair sites are unclear. Here, we have investigated the roles of several different polymerases during homologous recombination repair in Drosophila melanogaster. Using a gap repair assay, we found that homologous recombination is impaired in Drosophila lacking DNA polymerase zeta and, to a lesser extent, polymerase eta. In addition, the Pol32 protein, part of the polymerase delta complex, is needed for repair requiring extensive synthesis. Loss of Rev1, which interacts with multiple translesion polymerases, results in increased synthesis during gap repair. Together, our findings support a model in which translesion polymerases and the polymerase delta complex compete during homologous recombination repair. In addition, they establish Rev1 as a crucial factor that regulates the extent of repair synthesis.

  12. RecQL5 promotes genome stabilization through two parallel mechanisms--interacting with RNA polymerase II and acting as a helicase.

    Science.gov (United States)

    Islam, M Nurul; Fox, David; Guo, Rong; Enomoto, Takemi; Wang, Weidong

    2010-05-01

    The RecQL5 helicase is essential for maintaining genome stability and reducing cancer risk. To elucidate its mechanism of action, we purified a RecQL5-associated complex and identified its major component as RNA polymerase II (Pol II). Bioinformatics and structural modeling-guided mutagenesis revealed two conserved regions in RecQL5 as KIX and SRI domains, already known in transcriptional regulators for Pol II. The RecQL5-KIX domain binds both initiation (Pol IIa) and elongation (Pol IIo) forms of the polymerase, whereas the RecQL5-SRI domain interacts only with the elongation form. Fully functional RecQL5 requires both helicase activity and associations with the initiation polymerase, because mutants lacking either activity are partially defective in the suppression of sister chromatid exchange and resistance to camptothecin-induced DNA damage, and mutants lacking both activities are completely defective. We propose that RecQL5 promotes genome stabilization through two parallel mechanisms: by participation in homologous recombination-dependent DNA repair as a RecQ helicase and by regulating the initiation of Pol II to reduce transcription-associated replication impairment and recombination.

  13. Functional mapping of the fission yeast DNA polymerase δ B-subunit Cdc1 by site-directed and random pentapeptide insertion mutagenesis

    Directory of Open Access Journals (Sweden)

    Gray Fiona C

    2009-08-01

    Full Text Available Abstract Background DNA polymerase δ plays an essential role in chromosomal DNA replication in eukaryotic cells, being responsible for synthesising the bulk of the lagging strand. In fission yeast, Pol δ is a heterotetrameric enzyme comprising four evolutionarily well-conserved proteins: the catalytic subunit Pol3 and three smaller subunits Cdc1, Cdc27 and Cdm1. Pol3 binds directly to the B-subunit, Cdc1, which in turn binds the C-subunit, Cdc27. Human Pol δ comprises the same four subunits, and the crystal structure was recently reported of a complex of human p50 and the N-terminal domain of p66, the human orthologues of Cdc1 and Cdc27, respectively. Results To gain insights into the structure and function of Cdc1, random and directed mutagenesis techniques were used to create a collection of thirty alleles encoding mutant Cdc1 proteins. Each allele was tested for function in fission yeast and for binding of the altered protein to Pol3 and Cdc27 using the two-hybrid system. Additionally, the locations of the amino acid changes in each protein were mapped onto the three-dimensional structure of human p50. The results obtained from these studies identify amino acid residues and regions within the Cdc1 protein that are essential for interaction with Pol3 and Cdc27 and for in vivo function. Mutations specifically defective in Pol3-Cdc1 interactions allow the identification of a possible Pol3 binding surface on Cdc1. Conclusion In the absence of a three-dimensional structure of the entire Pol δ complex, the results of this study highlight regions in Cdc1 that are vital for protein function in vivo and provide valuable clues to possible protein-protein interaction surfaces on the Cdc1 protein that will be important targets for further study.

  14. Error-prone bypass of O6-methylguanine by DNA polymerase of Pseudomonas aeruginosa phage PaP1.

    Science.gov (United States)

    Gu, Shiling; Xiong, Jingyuan; Shi, Ying; You, Jia; Zou, Zhenyu; Liu, Xiaoying; Zhang, Huidong

    2017-09-01

    O 6 -Methylguanine (O 6 -MeG) is highly mutagenic and is commonly found in DNA exposed to methylating agents, generally leads to G:C to A:T mutagenesis. To study DNA replication encountering O 6 -MeG by the DNA polymerase (gp90) of P. aeruginosa phage PaP1, we analyzed steady-state and pre-steady-state kinetics of nucleotide incorporation opposite O 6 -MeG by gp90 exo - . O 6 -MeG partially inhibited full-length extension by gp90 exo - . O 6 -MeG greatly reduces dNTP incorporation efficiency, resulting in 67-fold preferential error-prone incorporation of dTTP than dCTP. Gp90 exo - extends beyond T:O 6 -MeG 2-fold more efficiently than C:O 6 -MeG. Incorporation of dCTP opposite G and incorporation of dCTP or dTTP opposite O 6 -MeG show fast burst phases. The pre-steady-state incorporation efficiency (k pol /K d,dNTP ) is decreased in the order of dCTP:G>dTTP:O 6 -MeG>dCTP:O 6 -MeG. The presence of O 6 -MeG at template does not affect the binding affinity of polymerase to DNA but it weakened their binding in the presence of dCTP and Mg 2+ . Misincorporation of dTTP opposite O 6 -MeG further weakens the binding affinity of polymerase to DNA. The priority of dTTP incorporation opposite O 6 -MeG is originated from the fact that dTTP can induce a faster conformational change step and a faster chemical step than dCTP. This study reveals that gp90 bypasses O 6 -MeG in an error-prone manner and provides further understanding in DNA replication encountering mutagenic alkylation DNA damage for P. aeruginosa phage PaP1. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. α,β-D-constrained nucleic acids are strong terminators of thermostable DNA polymerases in polymerase chain reaction.

    Directory of Open Access Journals (Sweden)

    Olivier Martínez

    Full Text Available (S(C5', R(P α,β-D- Constrained Nucleic Acids (CNA are dinucleotide building blocks that can feature either B-type torsional angle values or non-canonical values, depending on their 5'C and P absolute stereochemistry. These CNA are modified neither on the nucleobase nor on the sugar structure and therefore represent a new class of nucleotide with specific chemical and structural characteristics. They promote marked bending in a single stranded DNA so as to preorganize it into a loop-like structure, and they have been shown to induce rigidity within oligonucleotides. Following their synthesis, studies performed on CNA have only focused on the constraints that this family of nucleotides introduced into DNA. On the assumption that bending in a DNA template may produce a terminator structure, we investigated whether CNA could be used as a new strong terminator of polymerization in PCR. We therefore assessed the efficiency of CNA as a terminator in PCR, using triethylene glycol phosphate units as a control. Analyses were performed by denaturing gel electrophoresis and several PCR products were further analysed by sequencing. The results showed that the incorporation of only one CNA was always skipped by the polymerases tested. On the other hand, two CNA units always stopped proofreading polymerases, such as Pfu DNA polymerase, as expected for a strong replication terminator. Non-proofreading enzymes, e.g. Taq DNA polymerase, did not recognize this modification as a strong terminator although it was predominantly stopped by this structure. In conclusion, this first functional use of CNA units shows that these modified nucleotides can be used as novel polymerization terminators of proofreading polymerases. Furthermore, our results lead us to propose that CNA and their derivatives could be useful tools for investigating the behaviour of different classes of polymerases.

  16. DNA polymerase III of Escherichia coli is required for UV and ethyl methanesulfonate mutagenesis

    Energy Technology Data Exchange (ETDEWEB)

    Hagensee, M.E.; Timme, T.L.; Bryan, S.K.; Moses, R.E.

    1987-06-01

    Strains of Escherichia coli possessing the pcbA1 mutation, a functional DNA polymerase I, and a temperature-sensitive mutation in DNA polymerase III can survive at the restrictive temperature (43 degrees C) for DNA polymerase III. The mutation rate of the bacterial genome of such strains after exposure to either UV light or ethyl methanesulfonate was measured by its rifampicin resistance or amino acid requirements. In addition, Weigle mutagenesis of preirradiated lambda phage was also measured. In all cases, no increase in mutagenesis was noted at the restrictive temperature for DNA polymerase III. Introduction of a cloned DNA polymerase III gene returned the mutation rate of the bacterial genome as well as the Weigle mutagenesis to normal at 43 degrees C. Using a recA-lacZ fusion, the SOS response after UV irradiation was measured and found to be normal at the restrictive and permissive temperature for DNA polymerase III, as was induction of lambda prophage. Recombination was also normal at either temperature. Our studies demonstrate that a functional DNA polymerase III is strictly required for mutagenesis at a step other than SOS induction.

  17. PCR fidelity of pfu DNA polymerase and other thermostable DNA polymerases.

    OpenAIRE

    Cline, J; Braman, J C; Hogrefe, H H

    1996-01-01

    The replication fidelities of Pfu, Taq, Vent, Deep Vent and UlTma DNA polymerases were compared using a PCR-based forward mutation assay. Average error rates (mutation frequency/bp/duplication) increased as follows: Pfu (1.3 x 10(-6)) < Deep Vent (2.7 x 10(-6)) < Vent (2.8 x 10(-6)) < Taq (8.0 x 10(-6)) < < exo- Pfu and UlTma (approximately 5 x 10(-5)). Buffer optimization experiments indicated that Pfu fidelity was highest in the presence of 2-3 mM MgSO4 and 100-300 microM each dNTP and at p...

  18. Separation of DNA-dependent polymerase activities in Micrococcus radiodurans

    Energy Technology Data Exchange (ETDEWEB)

    Kitayama, S; Matsuyama, A [Institute of Physical and Chemical Research, Wako, Saitama (Japan)

    1977-03-02

    DNA polymerase activities in Micrococcus radiodurans were separated into two fractions after purification more than 2000 fold. They differ in pH optimum and residual activities in the absence of a full deoxyribonucleoside triphosphates complement. NAD partly inhibited one of the activities. Both activities were eluted as a single peak on gel filtration and sedimented at the same rate on glycerol gradient centrifugation. Molecular weight 140000 was calculated from Stokes radius and sedimentation constant. Deoxyribonuclease activity was detected on one of the polymerase activities which preferentially degraded double-stranded DNA. Priming activity of nicked DNA was reduced by ..gamma.. radiation. These results have been related to the possible roles in repair synthesis in vivo or DNA synthesis in permeable cells of M. radiodurans.

  19. Isolation and characterisation of the cDNA encoding a glycosylated accessory protein of pea chloroplast DNA polymerase.

    OpenAIRE

    Gaikwad, A; Tewari, K K; Kumar, D; Chen, W; Mukherjee, S K

    1999-01-01

    The cDNA encoding p43, a DNA binding protein from pea chloroplasts (ct) that binds to cognate DNA polymerase and stimulates the polymerase activity, has been cloned and characterised. The characteristic sequence motifs of hydroxyproline-rich glyco-proteins (HRGP) are present in the cDNA corres-ponding to the N-terminal domain of the mature p43. The protein was found to be highly O-arabinosylated. Chemically deglycosylated p43 (i.e. p29) retains its binding to both DNA and pea ct-DNA polymeras...

  20. Potent nonnucleoside reverse transcriptase inhibitors target HIV-1 Gag-Pol.

    Directory of Open Access Journals (Sweden)

    Anna Figueiredo

    2006-11-01

    Full Text Available Nonnucleoside reverse transcriptase inhibitors (NNRTIs target HIV-1 reverse transcriptase (RT by binding to a pocket in RT that is close to, but distinct, from the DNA polymerase active site and prevent the synthesis of viral cDNA. NNRTIs, in particular, those that are potent inhibitors of RT polymerase activity, can also act as chemical enhancers of the enzyme's inter-subunit interactions. However, the consequences of this chemical enhancement effect on HIV-1 replication are not understood. Here, we show that the potent NNRTIs efavirenz, TMC120, and TMC125, but not nevirapine or delavirdine, inhibit the late stages of HIV-1 replication. These potent NNRTIs enhanced the intracellular processing of Gag and Gag-Pol polyproteins, and this was associated with a decrease in viral particle production from HIV-1-transfected cells. The increased polyprotein processing is consistent with premature activation of the HIV-1 protease by NNRTI-enhanced Gag-Pol multimerization through the embedded RT sequence. These findings support the view that Gag-Pol multimerization is an important step in viral assembly and demonstrate that regulation of Gag-Pol/Gag-Pol interactions is a novel target for small molecule inhibitors of HIV-1 production. Furthermore, these drugs can serve as useful probes to further understand processes involved in HIV-1 particle assembly and maturation.

  1. Preparation of Phi29 DNA polymerase free of amplifiable DNA using ethidium monoazide, an ultraviolet-free light-emitting diode lamp and trehalose.

    Directory of Open Access Journals (Sweden)

    Hirokazu Takahashi

    Full Text Available We previously reported that multiply-primed rolling circle amplification (MRPCA using modified random RNA primers can amplify tiny amounts of circular DNA without producing any byproducts. However, contaminating DNA in recombinant Phi29 DNA polymerase adversely affects the outcome of MPRCA, especially for negative controls such as non-template controls. The amplified DNA in negative control casts doubt on the result of DNA amplification. Since Phi29 DNA polymerase has high affinity for both single-strand and double-stranded DNA, some amount of host DNA will always remain in the recombinant polymerase. Here we describe a procedure for preparing Phi29 DNA polymerase which is essentially free of amplifiable DNA. This procedure is realized by a combination of host DNA removal using appropriate salt concentrations, inactivation of amplifiable DNA using ethidium monoazide, and irradiation with visible light from a light-emitting diode lamp. Any remaining DNA, which likely exists as oligonucleotides captured by the Phi29 DNA polymerase, is degraded by the 3'-5' exonuclease activity of the polymerase itself in the presence of trehalose, used as an anti-aggregation reagent. Phi29 DNA polymerase purified by this procedure has little amplifiable DNA, resulting in reproducible amplification of at least ten copies of plasmid DNA without any byproducts and reducing reaction volume. This procedure could aid the amplification of tiny amounts DNA, thereby providing clear evidence of contamination from laboratory environments, tools and reagents.

  2. Mechanistic Studies with DNA Polymerases Reveal Complex Outcomes following Bypass of DNA Damage

    Directory of Open Access Journals (Sweden)

    Robert L. Eoff

    2010-01-01

    Full Text Available DNA is a chemically reactive molecule that is subject to many different covalent modifications from sources that are both endogenous and exogenous in origin. The inherent instability of DNA is a major obstacle to genomic maintenance and contributes in varying degrees to cellular dysfunction and disease in multi-cellular organisms. Investigations into the chemical and biological aspects of DNA damage have identified multi-tiered and overlapping cellular systems that have evolved as a means of stabilizing the genome. One of these pathways supports DNA replication events by in a sense adopting the mantra that one must “make the best of a bad situation” and tolerating covalent modification to DNA through less accurate copying of the damaged region. Part of this so-called DNA damage tolerance pathway involves the recruitment of specialized DNA polymerases to sites of stalled or collapsed replication forks. These enzymes have unique structural and functional attributes that often allow bypass of adducted template DNA and successful completion of genomic replication. What follows is a selective description of the salient structural features and bypass properties of specialized DNA polymerases with an emphasis on Y-family members.

  3. Site-specifically modified oligodeoxyribonucleotides as templates for Escherichia coli DNA polymerase I

    International Nuclear Information System (INIS)

    O'Connor, D.; Stoehrer, G.

    1985-01-01

    Oligodeoxyribonucleotides with site-specific modifications have been used as substrates for Escherichia coli DNA polymerase I holoenzyme and Klenow fragment. Modifications included the bulky guanine-8-aminofluorene adduct and a guanine oxidation product resembling the product of photosensitized DNA oxidation. By a combination of primers and nick-mers, conditions of single-strand-directed DNA synthesis and nick-translation could be created. The results show that the polymerase can bypass both types of lesions. Bypass occurs on a single-stranded template but is facilitated on a nicked, double-stranded template. Only purines, with guanine more favored than adenine, are incorporated across both lesions. The results indicate that site-specifically modified oligonucleotides can be sensitive probes for the action of polymerases on damaged templates. They also suggest a function for polymerase I, in its nick-translation capacity, during DNA repair and mutagenesis

  4. The interplay between polymerase organization and nucleosome occupancy along DNA : How dynamic roadblocks on the DNA induce the formation of RNA polymerase pelotons

    NARCIS (Netherlands)

    van den Berg, A.A.

    2017-01-01

    During transcription RNA polymerase (RNAP) moves along a DNA molecule to copy the information on the DNA to an RNA molecule. Many textbook pictures show an RNAP sliding along empty DNA, but in reality it is crowded on the DNA and RNAP competes for space with many proteins such as other RNAP’s and

  5. Conformational Selection and Induced Fit for RNA Polymerase and RNA/DNA Hybrid Backtracked Recognition

    Directory of Open Access Journals (Sweden)

    Haifeng eChen

    2015-11-01

    Full Text Available RNA polymerase catalyzes transcription with a high fidelity. If DNA/RNA mismatch or DNA damage occurs downstream, a backtracked RNA polymerase can proofread this situation. However, the backtracked mechanism is still poorly understood. Here we have performed multiple explicit-solvent molecular dynamics (MD simulations on bound and apo DNA/RNA hybrid to study backtracked recognition. MD simulations at room temperature suggest that specific electrostatic interactions play key roles in the backtracked recognition between the polymerase and DNA/RNA hybrid. Kinetics analysis at high temperature shows that bound and apo DNA/RNA hybrid unfold via a two-state process. Both kinetics and free energy landscape analyses indicate that bound DNA/RNA hybrid folds in the order of DNA/RNA contracting, the tertiary folding and polymerase binding. The predicted Φ-values suggest that C7, G9, dC12, dC15 and dT16 are key bases for the backtracked recognition of DNA/RNA hybrid. The average RMSD values between the bound structures and the corresponding apo ones and Kolmogorov-Smirnov (KS P test analyses indicate that the recognition between DNA/RNA hybrid and polymerase might follow an induced fit mechanism for DNA/RNA hybrid and conformation selection for polymerase. Furthermore, this method could be used to relative studies of specific recognition between nucleic acid and protein.

  6. Distinct energetics and closing pathways for DNA polymerase β with 8-oxoG template and different incoming nucleotides

    Directory of Open Access Journals (Sweden)

    Wang Yanli

    2007-02-01

    Full Text Available Abstract Background 8-Oxoguanine (8-oxoG is a common oxidative lesion frequently encountered by DNA polymerases such as the repair enzyme DNA polymerase β (pol β. To interpret in atomic and energetic detail how pol β processes 8-oxoG, we apply transition path sampling to delineate closing pathways of pol β 8-oxoG complexes with dCTP and dATP incoming nucleotides and compare the results to those of the nonlesioned G:dCTP and G:dATPanalogues. Results Our analyses show that the closing pathways of the 8-oxoG complexes are different from one another and from the nonlesioned analogues in terms of the individual transition states along each pathway, associated energies, and the stability of each pathway's closed state relative to the corresponding open state. In particular, the closed-to-open state stability difference in each system establishes a hierarchy of stability (from high to low as G:C > 8-oxoG:C > 8-oxoG:A > G:A, corresponding to -3, -2, 2, 9 kBT, respectively. This hierarchy of closed state stability parallels the experimentally observed processing efficiencies for the four pairs. Network models based on the calculated rate constants in each pathway indicate that the closed species are more populated than the open species for 8-oxoG:dCTP, whereas the opposite is true for 8-oxoG:dATP. Conclusion These results suggest that the lower insertion efficiency (larger Km for dATP compared to dCTP opposite 8-oxoG is caused by a less stable closed-form of pol β, destabilized by unfavorable interactions between Tyr271 and the mispair. This stability of the closed vs. open form can also explain the higher insertion efficiency for 8-oxoG:dATP compared to the nonlesioned G:dATP pair, which also has a higher overall conformational barrier. Our study offers atomic details of the complexes at different states, in addition to helping interpret the different insertion efficiencies of dATP and dCTP opposite 8-oxoG and G.

  7. Mitochondrial DNA polymerase from embryos of Drosophila melanogaster: purification, subunit structure, and partial characterization

    International Nuclear Information System (INIS)

    Wernette, C.M.; Kaguni, L.S.

    1986-01-01

    The mitochondrial DNA polymerase has been purified to near-homogeneity from early embryos of Drosophila melanogaster. Sodium dodecyl sulfate gel electrophoresis of the highly purified enzyme reveals two polypeptides with molecular masses of 125,000 and 35,000 daltons, in a ratio of 1:1. The enzyme has a sedimentation coefficient of 7.6 S and a stokes radius of 51 A. Taken together, the data suggest that the D. melanogaster DNA polymerase γ is a heterodimer. DNA polymerase activity gel analysis has allowed the assignment of the DNA polymerization function to the large subunit. The DNA polymerase exhibits a remarkable ability to utilize efficiently a variety of template-primers including gapped DNA, poly(rA).oligo(dT) and singly primed phiX174 DNA. Both the crude and the highly purified enzymes are stimulated by KCl, and inhibited by dideoxythymidine triphosphate and by N-ethylmaleimide. Thus, the catalytic properties of the near-homogeneous Drosophila enzyme are consistent with those of DNA polymerase γ as partially purified from several vertebrates

  8. Molecular Basis for DNA Double-Strand Break Annealing and Primer Extension by an NHEJ DNA Polymerase

    Directory of Open Access Journals (Sweden)

    Nigel C. Brissett

    2013-11-01

    Full Text Available Nonhomologous end-joining (NHEJ is one of the major DNA double-strand break (DSB repair pathways. The mechanisms by which breaks are competently brought together and extended during NHEJ is poorly understood. As polymerases extend DNA in a 5′-3′ direction by nucleotide addition to a primer, it is unclear how NHEJ polymerases fill in break termini containing 3′ overhangs that lack a primer strand. Here, we describe, at the molecular level, how prokaryotic NHEJ polymerases configure a primer-template substrate by annealing the 3′ overhanging strands from opposing breaks, forming a gapped intermediate that can be extended in trans. We identify structural elements that facilitate docking of the 3′ ends in the active sites of adjacent polymerases and reveal how the termini act as primers for extension of the annealed break, thus explaining how such DSBs are extended in trans. This study clarifies how polymerases couple break-synapsis to catalysis, providing a molecular mechanism to explain how primer extension is achieved on DNA breaks.

  9. DNA Polymerase κ Is a Key Cellular Factor for the Formation of Covalently Closed Circular DNA of Hepatitis B Virus.

    Directory of Open Access Journals (Sweden)

    Yonghe Qi

    2016-10-01

    Full Text Available Hepatitis B virus (HBV infection of hepatocytes begins by binding to its cellular receptor sodium taurocholate cotransporting polypeptide (NTCP, followed by the internalization of viral nucleocapsid into the cytoplasm. The viral relaxed circular (rc DNA genome in nucleocapsid is transported into the nucleus and converted into covalently closed circular (ccc DNA to serve as a viral persistence reservoir that is refractory to current antiviral therapies. Host DNA repair enzymes have been speculated to catalyze the conversion of rcDNA to cccDNA, however, the DNA polymerase(s that fills the gap in the plus strand of rcDNA remains to be determined. Here we conducted targeted genetic screening in combination with chemical inhibition to identify the cellular DNA polymerase(s responsible for cccDNA formation, and exploited recombinant HBV with capsid coding deficiency which infects HepG2-NTCP cells with similar efficiency of wild-type HBV to assure cccDNA synthesis is exclusively from de novo HBV infection. We found that DNA polymerase κ (POLK, a Y-family DNA polymerase with maximum activity in non-dividing cells, substantially contributes to cccDNA formation during de novo HBV infection. Depleting gene expression of POLK in HepG2-NTCP cells by either siRNA knockdown or CRISPR/Cas9 knockout inhibited the conversion of rcDNA into cccDNA, while the diminished cccDNA formation in, and hence the viral infection of, the knockout cells could be effectively rescued by ectopic expression of POLK. These studies revealed that POLK is a crucial host factor required for cccDNA formation during a de novo HBV infection and suggest that POLK may be a potential target for developing antivirals against HBV.

  10. Cell cycle phase dependent role of DNA polymerase beta in DNA repair and survival after ionizing radiation.

    NARCIS (Netherlands)

    Vermeulen, C.; Verwijs-Janssen, M.; Begg, A.C.; Vens, C.

    2008-01-01

    PURPOSE: The purpose of the present study was to determine the role of DNA polymerase beta in repair and response after ionizing radiation in different phases of the cell cycle. METHODS AND MATERIALS: Synchronized cells deficient and proficient in DNA polymerase beta were irradiated in different

  11. C-terminal phenylalanine of bacteriophage T7 single-stranded DNA-binding protein is essential for strand displacement synthesis by T7 DNA polymerase at a nick in DNA.

    Science.gov (United States)

    Ghosh, Sharmistha; Marintcheva, Boriana; Takahashi, Masateru; Richardson, Charles C

    2009-10-30

    Single-stranded DNA-binding protein (gp2.5), encoded by gene 2.5 of bacteriophage T7, plays an essential role in DNA replication. Not only does it remove impediments of secondary structure in the DNA, it also modulates the activities of the other replication proteins. The acidic C-terminal tail of gp2.5, bearing a C-terminal phenylalanine, physically and functionally interacts with the helicase and DNA polymerase. Deletion of the phenylalanine or substitution with a nonaromatic amino acid gives rise to a dominant lethal phenotype, and the altered gp2.5 has reduced affinity for T7 DNA polymerase. Suppressors of the dominant lethal phenotype have led to the identification of mutations in gene 5 that encodes the T7 DNA polymerase. The altered residues in the polymerase are solvent-exposed and lie in regions that are adjacent to the bound DNA. gp2.5 lacking the C-terminal phenylalanine has a lower affinity for gp5-thioredoxin relative to the wild-type gp2.5, and this affinity is partially restored by the suppressor mutations in DNA polymerase. gp2.5 enables T7 DNA polymerase to catalyze strand displacement DNA synthesis at a nick in DNA. The resulting 5'-single-stranded DNA tail provides a loading site for T7 DNA helicase. gp2.5 lacking the C-terminal phenylalanine does not support this event with wild-type DNA polymerase but does to a limited extent with T7 DNA polymerase harboring the suppressor mutations.

  12. C-terminal Phenylalanine of Bacteriophage T7 Single-stranded DNA-binding Protein Is Essential for Strand Displacement Synthesis by T7 DNA Polymerase at a Nick in DNA*

    Science.gov (United States)

    Ghosh, Sharmistha; Marintcheva, Boriana; Takahashi, Masateru; Richardson, Charles C.

    2009-01-01

    Single-stranded DNA-binding protein (gp2.5), encoded by gene 2.5 of bacteriophage T7, plays an essential role in DNA replication. Not only does it remove impediments of secondary structure in the DNA, it also modulates the activities of the other replication proteins. The acidic C-terminal tail of gp2.5, bearing a C-terminal phenylalanine, physically and functionally interacts with the helicase and DNA polymerase. Deletion of the phenylalanine or substitution with a nonaromatic amino acid gives rise to a dominant lethal phenotype, and the altered gp2.5 has reduced affinity for T7 DNA polymerase. Suppressors of the dominant lethal phenotype have led to the identification of mutations in gene 5 that encodes the T7 DNA polymerase. The altered residues in the polymerase are solvent-exposed and lie in regions that are adjacent to the bound DNA. gp2.5 lacking the C-terminal phenylalanine has a lower affinity for gp5-thioredoxin relative to the wild-type gp2.5, and this affinity is partially restored by the suppressor mutations in DNA polymerase. gp2.5 enables T7 DNA polymerase to catalyze strand displacement DNA synthesis at a nick in DNA. The resulting 5′-single-stranded DNA tail provides a loading site for T7 DNA helicase. gp2.5 lacking the C-terminal phenylalanine does not support this event with wild-type DNA polymerase but does to a limited extent with T7 DNA polymerase harboring the suppressor mutations. PMID:19726688

  13. A specific subdomain in φ29 DNA polymerase confers both processivity and strand-displacement capacity

    Science.gov (United States)

    Rodríguez, Irene; Lázaro, José M.; Blanco, Luis; Kamtekar, Satwik; Berman, Andrea J.; Wang, Jimin; Steitz, Thomas A.; Salas, Margarita; de Vega, Miguel

    2005-01-01

    Recent crystallographic studies of φ29 DNA polymerase have provided structural insights into its strand displacement and processivity. A specific insertion named terminal protein region 2 (TPR2), present only in protein-primed DNA polymerases, together with the exonuclease, thumb, and palm subdomains, forms two tori capable of interacting with DNA. To analyze the functional role of this insertion, we constructed a φ29 DNA polymerase deletion mutant lacking TPR2 amino acid residues Asp-398 to Glu-420. Biochemical analysis of the mutant DNA polymerase indicates that its DNA-binding capacity is diminished, drastically decreasing its processivity. In addition, removal of the TPR2 insertion abolishes the intrinsic capacity of φ29 DNA polymerase to perform strand displacement coupled to DNA synthesis. Therefore, the biochemical results described here directly demonstrate that TPR2 plays a critical role in strand displacement and processivity. PMID:15845765

  14. Effects of DNA polymerase inhibitors on replicative and repair DNA synthesis in ultraviolet-irradiated HeLa cells

    International Nuclear Information System (INIS)

    Morita, T.; Nakamura, H.; Tsutsui, Y.; Nishiyama, Y.; Yoshida, S.

    1982-01-01

    Aphidicolin specifically inhibits eukaryotic DNA polymerase α, while 2',3'-dideoxythymidine 5'-triphosphate (d 2 TTP) inhibits DNA polymerase ν and ν but not α. 1-ν-D-Arabinofuranosylcytosine 5'-triphosphate (araCTP) inhibits both DNA polymerase α and ν although to a different extent. Here we measured the effects of these inhibitors on repair DNA synthesis of U.V.-irradiated HeLa cells by two different methods. Firstly, aphidicolin, 1-ν-D-arabinofuranosylcytosine (araC, a precursor of araCTP) and 2',3'-dideoxythimidine (d 2 Thd, a precursor of d 2 TTP) were added directly to the culture medium. In this case, aphidicolin and araC strongly inhibited replicative DNA synthesis of HeLa cells, and they also inhibited repair synthesis after U.V.-irradiation but to a much lesser extent. In contrast, high concentrations of d 2 Thd inhibited repair DNA synthesis to a higher extent than replicative DNA synthesis. Secondly, the active form of inhibitor, d 2 TTP, was microinjected directly into cytoplasm or nuclei or U.V.-irradiated HeLa cells. Microinjection of d 2 TTP effectively inhibited repair synthesis. The microinjection of d 2 TTP, into either cytoplasm or nucleus, strongly inhibited replicative synthesis. These results might indicate that multiple DNA polymerases are involved in repair synthesis as well as in replicative synthesis

  15. Effect of the uvr D3 mutation on ultraviolet radiation-induced DNA-repair replication in Escherichia coli K12

    International Nuclear Information System (INIS)

    Carlson, K.M.; Smith, K.C.

    1981-01-01

    Ultraviolet-radiation-induced DNA-repair replication was measured in wild-type, polA1, uvrD3, and polA1 uvrD3 strains of Escherichia coli K 12. A large stimulation of repair replication was observed in the uvrD3 strain, compared to the wild-type and polA1 strains. This enhanced repair replication was reduced in the polA1 uvrD3 strain. Therefore, a uvrD3 mutation appears to affect the amount of repair replication performed by DNA polymerase I. In the polA1 strain, there also appears to be an effect of the uvrD3 mutation on the amount of repair replication performed by DNA polymerase III (and/or II). The enhanced repair replication observed for the uvrD3 strains appears to be in response to the enhanced DNA degradation observed for these strains. (orig.)

  16. Effects of coordination of diammineplatinum(II) with DNA on the activities of Escherichia coli DNA polymerase I

    International Nuclear Information System (INIS)

    Bernges, F.; Holler, E.

    1988-01-01

    The effects of the reaction of cis- and trans-diamminedichloroplatinum(II) with DNA have been measured with regard to DNA synthesis, 3'-5' exonuclease (proofreading), and 5'-3' exonuclease (repair) activities of Escherichia coli DNA polymerase I. Both isomers inhibit DNA synthetic activity of the polymerase through an increase in K/sub m/ values and a decrease in V/sub max/ values for platinated DNA but not for the nucleoside 5'-triphosphates as the varied substrates. The inhibition is a consequence of lowered binding affinity between platinated DNA and DNA polymerase, and of a platination-induced separation of template and primer strands. Strand separation enhances initial rates of 3'-5' excision of [ 3 H]dCMP from platinated DNA (proofreading), while total excision levels of nucleotides are decreased. In contrast to proofreading activity, the 5'-3' exonuclease activity (repair) discriminates between DNA which had reacted with cis- and with trans-diamminedichloroplatinum(II). While both initial rates and total excision are inhibited for the cis isomer, they are almost not affected for the trans isomer. This differential effect could explain why bacterial growth inhibition requires much higher concentrations of trans- than cis-diamminedichloroplatinum(II)

  17. Chromosomal location of the human gene for DNA polymerase β

    International Nuclear Information System (INIS)

    McBride, O.W.; Zmudzka, B.Z.; Wilson, S.H.

    1987-01-01

    Inhibition studies indicate that DNA polymerase β has a synthetic role in DNA repair after exposure of mammalian cells to some types of DNA-damaging agents. The primary structure of the enzyme is highly conserved in vertebrates, and nearly full-length cDNAs for the enzyme were recently cloned from mammalian cDNA libraries. Southern blot analysis of DNA from a panel of human-rodent somatic cell hybrids, using portions of the cDNA as probe, indicates that the gene for human DNA polymerase β is single copy and located on the short arm or proximal long arm of chromosome 8 (8pter-8q22). A restriction fragment length polymorphism (RFLP) was detected in normal individuals by using a probe from the 5' end of the cDNA, and this RFLP probably is due to an insertion or duplication of DNA in 20-25% of the population. This restriction site can be used as one marker for chromosome 8 genetic linkage studies and for family studies of traits potentially involving this DNA repair gene

  18. Chromatin Constrains the Initiation and Elongation of DNA Replication.

    Science.gov (United States)

    Devbhandari, Sujan; Jiang, Jieqing; Kumar, Charanya; Whitehouse, Iestyn; Remus, Dirk

    2017-01-05

    Eukaryotic chromosomal DNA is faithfully replicated in a complex series of cell-cycle-regulated events that are incompletely understood. Here we report the reconstitution of DNA replication free in solution with purified proteins from the budding yeast Saccharomyces cerevisiae. The system recapitulates regulated bidirectional origin activation; synthesis of leading and lagging strands by the three replicative DNA polymerases Pol α, Pol δ, and Pol ε; and canonical maturation of Okazaki fragments into continuous daughter strands. We uncover a dual regulatory role for chromatin during DNA replication: promoting origin dependence and determining Okazaki fragment length by restricting Pol δ progression. This system thus provides a functional platform for the detailed mechanistic analysis of eukaryotic chromosome replication. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Role of DNA polymerase α in chromosomal aberration production by ionizing radiation

    International Nuclear Information System (INIS)

    Bender, M.A.

    1983-01-01

    Aphidicolin is a tetracyclic diterpinoid fungal antibiotic which inhibits DNA synthesis in eukaryotic cells by interfering specifically with DNA polymerase α, apparently by binding to and inactivating the DNA-polymerase α complex. We have shown that aphidicolin, like other inhibitors of DNA synthesis, both induces chromosomal aberrations in human peripheral lymphocytes, and, as a post-treatment, interacts synergistically with x rays to produce greatly enhanced aberration yields. The present experiments explore the effects of aphidicolin in human lymphocytes in the post-DNA-synthetic G 2 phase of the cell cycle. These experiments utilized labeling with tritiated thymidine to positively identify cells in the S phase at the time of treatment, and used serial colcemid collections and fixations to determine aberration yields over as much of the G 2 phase as feasible. Because DNA polymerase α is the only DNA synthetic or repair enzyme known to be affected by aphidicolin, we infer that this enzyme is directly involved in the repair of DNA lesions which can result in visible chromosomal aberrations. (DT)

  20. PIP degron proteins, substrates of CRL4Cdt2, and not PIP boxes, interfere with DNA polymerase η and κ focus formation on UV damage.

    Science.gov (United States)

    Tsanov, Nikolay; Kermi, Chames; Coulombe, Philippe; Van der Laan, Siem; Hodroj, Dana; Maiorano, Domenico

    2014-04-01

    Proliferating cell nuclear antigen (PCNA) is a well-known scaffold for many DNA replication and repair proteins, but how the switch between partners is regulated is currently unclear. Interaction with PCNA occurs via a domain known as a PCNA-Interacting Protein motif (PIP box). More recently, an additional specialized PIP box has been described, the « PIP degron », that targets PCNA-interacting proteins for proteasomal degradation via the E3 ubiquitin ligase CRL4(Cdt2). Here we provide evidence that CRL4(Cdt2)-dependent degradation of PIP degron proteins plays a role in the switch of PCNA partners during the DNA damage response by facilitating accumulation of translesion synthesis DNA polymerases into nuclear foci. We show that expression of a nondegradable PIP degron (Cdt1) impairs both Pol η and Pol κ focus formation on ultraviolet irradiation and reduces cell viability, while canonical PIP box-containing proteins have no effect. Furthermore, we identify PIP degron-containing peptides from several substrates of CRL4(Cdt2) as efficient inhibitors of Pol η foci formation. By site-directed mutagenesis we show that inhibition depends on a conserved threonine residue that confers high affinity for PCNA-binding. Altogether these findings reveal an important regulative role for the CRL4(Cdt2) pathway in the switch of PCNA partners on DNA damage.

  1. Amplified Detection of the Aptamer-Vanillin Complex with the Use of Bsm DNA Polymerase.

    Science.gov (United States)

    Andrianova, Mariia; Komarova, Natalia; Grudtsov, Vitaliy; Kuznetsov, Evgeniy; Kuznetsov, Alexander

    2017-12-26

    The electrochemical detection of interactions between aptamers and low-molecular-weight targets often lacks sensitivity. Signal amplification improves the detection of the aptamer-analyte complex; Bsm DNA polymerase was used to amplify the signal from the interaction of vanillin and its aptamer named Van_74 on an ion-sensitive field-effect transistor (ISFET)-based biosensor. The aptamer was immobilized on the ISFET sensitive surface. A short DNA probe was hybridized with the aptamer and dissociated from it upon vanillin addition. A free probe interacted with a special DNA molecular beacon initiated the Bsm DNA polymerase reaction that was detected by ISFET. A buffer solution suitable for both aptamer action and Bsm DNA polymerase activity was determined. The ISFET was shown to detect the Bsm DNA polymerase reaction under the selected conditions. Vanillin at different concentrations (1 × 10 -6 -1 × 10 -8 M) was detected using the biosensor with signal amplification. The developed detection system allowed for the determination of vanillin, starting at a 10 -8 M concentration. Application of the Bsm DNA polymerase resulted in a 15.5 times lower LoD when compared to the biosensor without signal amplification (10.1007/s00604-017-2586-4).

  2. The helicase domain of Polθ counteracts RPA to promote alt-NHEJ.

    Science.gov (United States)

    Mateos-Gomez, Pedro A; Kent, Tatiana; Deng, Sarah K; McDevitt, Shane; Kashkina, Ekaterina; Hoang, Trung M; Pomerantz, Richard T; Sfeir, Agnel

    2017-12-01

    Mammalian polymerase theta (Polθ) is a multifunctional enzyme that promotes error-prone DNA repair by alternative nonhomologous end joining (alt-NHEJ). Here we present structure-function analyses that reveal that, in addition to the polymerase domain, Polθ-helicase activity plays a central role during double-strand break (DSB) repair. Our results show that the helicase domain promotes chromosomal translocations by alt-NHEJ in mouse embryonic stem cells and also suppresses CRISPR-Cas9- mediated gene targeting by homologous recombination (HR). In vitro assays demonstrate that Polθ-helicase activity facilitates the removal of RPA from resected DSBs to allow their annealing and subsequent joining by alt-NHEJ. Consistent with an antagonistic role for RPA during alt-NHEJ, inhibition of RPA1 enhances end joining and suppresses recombination. Taken together, our results reveal that the balance between HR and alt-NHEJ is controlled by opposing activities of Polθ and RPA, providing further insight into the regulation of repair-pathway choice in mammalian cells.

  3. Effect of neonatal undernutrition on various forms of DNA-dependent DNA polymerases in cerebellum and liver of rat

    International Nuclear Information System (INIS)

    Baksi, K.; Kumar, A.

    1978-01-01

    Effect of neonatal undernutrition on the two forms of DNA polymerases obtained by DEAF-cellulose column chromatography of the solubilized nuclei and the high speed supernatant fractions of cerebellum and liver of rats has been studied. The form of DNA polymerase eluting with 0.1 M potassium phosphate buffer (pH 7.5) was significantly reduced, whereas that eluting with 0.3 M buffer (pH 7.5) was devoid of neonatal undernutrition effect. The properties of the separated DNA polymerases, both from cerebellum and liver, of control and undernourished groups were also studied. [Me- 3 H]thymidine-5--'triphosphate has been used in the study. (author)

  4. Whole Blood PCR Amplification with Pfu DNA Polymerase and Its Application in Single-Nucleotide Polymorphism Analysis.

    Science.gov (United States)

    Liu, Er-Ping; Wang, Yan; He, Xiao-Hui; Guan, Jun-Jie; Wang, Jin; Qin, Zheng-Hong; Sun, Wan-Ping

    2015-11-01

    Point-of-care genetic analysis may require polymerase chain reaction (PCR) to be carried out on whole blood. However, human blood contains natural inhibitors of PCR such as hemoglobin, immunoglobulin G, lactoferrin, and proteases, as well as anticoagulant agents, including EDTA and heparin that can reduce whole blood PCR efficiency. Our purpose was to develop a highly specific, direct whole blood single-nucleotide polymorphism (SNP) analysis method based on allele-specific (AS) PCR that is mediated by Pfu DNA polymerase and phosphorothioate-modified AS primers. At high Mg(2+) concentrations, Pfu DNA polymerase efficiently amplified genomic DNA in a reaction solution containing up to 14% whole blood. Among the three anticoagulants tested, Pfu DNA polymerase showed the highest activity with sodium citrate. Meanwhile, Triton X-100 and betaine inhibited Pfu DNA polymerase activity in whole blood PCR, whereas trehalose had virtually no effect. These findings provided for the development of a low-cost, simple, and fast direct whole blood genotyping method that uses Pfu DNA polymerase combined with phosphorothioate AS primers for CYP2C9*3 and VKORC1(-1639) loci. With its high DNA amplification efficiency and tolerance of various blood conditions, Pfu DNA polymerase can be used in clinical laboratories to analyze SNPs in whole blood samples.

  5. Identification of DNA polymerase molecules repairing DNA irradiated damage and molecular biological study on modified factors of mutation rate

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, Koichi; Inoue, Shuji [National Inst. of Healthand Nutrition, Tokyo (Japan)

    1999-02-01

    DNA repairing polymerase has not been identified in human culture cells because the specificities of enzyme inhibitors used in previous studies were not so high. In this study, anti-sense oligonucleotides were transfected into human fibroblast cells by electroporation and several clones selected by geneticin treatment were found to express the RNA of the incorporated DNA. However, the expression was not significant and its reproducibility was poor. Then, a study on repairing mechanism was made using XP30 RO and XP 115 LO cells which are variant cells of xeroderma pigmentosum, a human hereditary disease aiming to identify the DNA polymerase related to the disease. There were abnormalities in DNA polymerase subunit {delta} or {epsilon} which consists DNA replication complex. Thus, it was suggested that the DNA replication of these mutant cells might terminate at the site containing such abnormality. (M.N.)

  6. Checkpoint Kinase Rad53 Couples Leading- and Lagging-Strand DNA Synthesis under Replication Stress.

    Science.gov (United States)

    Gan, Haiyun; Yu, Chuanhe; Devbhandari, Sujan; Sharma, Sushma; Han, Junhong; Chabes, Andrei; Remus, Dirk; Zhang, Zhiguo

    2017-10-19

    The checkpoint kinase Rad53 is activated during replication stress to prevent fork collapse, an essential but poorly understood process. Here we show that Rad53 couples leading- and lagging-strand synthesis under replication stress. In rad53-1 cells stressed by dNTP depletion, the replicative DNA helicase, MCM, and the leading-strand DNA polymerase, Pol ε, move beyond the site of DNA synthesis, likely unwinding template DNA. Remarkably, DNA synthesis progresses further along the lagging strand than the leading strand, resulting in the exposure of long stretches of single-stranded leading-strand template. The asymmetric DNA synthesis in rad53-1 cells is suppressed by elevated levels of dNTPs in vivo, and the activity of Pol ε is compromised more than lagging-strand polymerase Pol δ at low dNTP concentrations in vitro. Therefore, we propose that Rad53 prevents the generation of excessive ssDNA under replication stress by coordinating DNA unwinding with synthesis of both strands. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Polymerase chain reaction and conventional DNA tests in detection of HPV DNA in cytologically normal and abnormal cervical scrapes

    DEFF Research Database (Denmark)

    Kalia, A.; Jalava, T.; Nieminen, P.

    1992-01-01

    Med.mikrobiologi, polymerase chain reaction, DNA tests, human papillomavirus (HPV), cervical smear, hybridisation, cytologi, affiProbe HPV test, ViraType test......Med.mikrobiologi, polymerase chain reaction, DNA tests, human papillomavirus (HPV), cervical smear, hybridisation, cytologi, affiProbe HPV test, ViraType test...

  8. Hepatitis B virus DNA polymerase gene polymorphism based ...

    African Journals Online (AJOL)

    Hepatitis B virus DNA polymerase gene polymorphism based prediction of genotypes in chronic HBV patients from Western India. Yashwant G. Chavan, Sharad R. Pawar, Minal Wani, Amol D. Raut, Rabindra N. Misra ...

  9. Amplified Detection of the Aptamer–Vanillin Complex with the Use of Bsm DNA Polymerase

    Directory of Open Access Journals (Sweden)

    Mariia Andrianova

    2017-12-01

    Full Text Available The electrochemical detection of interactions between aptamers and low-molecular-weight targets often lacks sensitivity. Signal amplification improves the detection of the aptamer-analyte complex; Bsm DNA polymerase was used to amplify the signal from the interaction of vanillin and its aptamer named Van_74 on an ion-sensitive field-effect transistor (ISFET-based biosensor. The aptamer was immobilized on the ISFET sensitive surface. A short DNA probe was hybridized with the aptamer and dissociated from it upon vanillin addition. A free probe interacted with a special DNA molecular beacon initiated the Bsm DNA polymerase reaction that was detected by ISFET. A buffer solution suitable for both aptamer action and Bsm DNA polymerase activity was determined. The ISFET was shown to detect the Bsm DNA polymerase reaction under the selected conditions. Vanillin at different concentrations (1 × 10−6–1 × 10−8 M was detected using the biosensor with signal amplification. The developed detection system allowed for the determination of vanillin, starting at a 10−8 M concentration. Application of the Bsm DNA polymerase resulted in a 15.5 times lower LoD when compared to the biosensor without signal amplification (10.1007/s00604-017-2586-4.

  10. Fidelity and mutational spectrum of Pfu DNA polymerase on a human mitochondrial DNA sequence.

    Science.gov (United States)

    André, P; Kim, A; Khrapko, K; Thilly, W G

    1997-08-01

    The study of rare genetic changes in human tissues requires specialized techniques. Point mutations at fractions at or below 10(-6) must be observed to discover even the most prominent features of the point mutational spectrum. PCR permits the increase in number of mutant copies but does so at the expense of creating many additional mutations or "PCR noise". Thus, each DNA sequence studied must be characterized with regard to the DNA polymerase and conditions used to avoid interpreting a PCR-generated mutation as one arising in human tissue. The thermostable DNA polymerase derived from Pyrococcus furiosus designated Pfu has the highest fidelity of any DNA thermostable polymerase studied to date, and this property recommends it for analyses of tissue mutational spectra. Here, we apply constant denaturant capillary electrophoresis (CDCE) to separate and isolate the products of DNA amplification. This new strategy permitted direct enumeration and identification of point mutations created by Pfu DNA polymerase in a 96-bp low melting domain of a human mitochondrial sequence despite the very low mutant fractions generated in the PCR process. This sequence, containing part of the tRNA glycine and NADH dehydrogenase subunit 3 genes, is the target of our studies of mitochondrial mutagenesis in human cells and tissues. Incorrectly synthesized sequences were separated from the wild type as mutant/wild-type heteroduplexes by sequential enrichment on CDCE. An artificially constructed mutant was used as an internal standard to permit calculation of the mutant fraction. Our study found that the average error rate (mutations per base pair duplication) of Pfu was 6.5 x 10(-7), and five of its more frequent mutations (hot spots) consisted of three transversions (GC-->TA, AT-->TA, and AT-->CG), one transition (AT-->GC), and one 1-bp deletion (in an AAAAAA sequence). To achieve an even higher sensitivity, the amount of Pfu-induced mutants must be reduced.

  11. Eukaryotic DNA Replication Fork.

    Science.gov (United States)

    Burgers, Peter M J; Kunkel, Thomas A

    2017-06-20

    This review focuses on the biogenesis and composition of the eukaryotic DNA replication fork, with an emphasis on the enzymes that synthesize DNA and repair discontinuities on the lagging strand of the replication fork. Physical and genetic methodologies aimed at understanding these processes are discussed. The preponderance of evidence supports a model in which DNA polymerase ε (Pol ε) carries out the bulk of leading strand DNA synthesis at an undisturbed replication fork. DNA polymerases α and δ carry out the initiation of Okazaki fragment synthesis and its elongation and maturation, respectively. This review also discusses alternative proposals, including cellular processes during which alternative forks may be utilized, and new biochemical studies with purified proteins that are aimed at reconstituting leading and lagging strand DNA synthesis separately and as an integrated replication fork.

  12. An isolated Hda-clamp complex is functional in the regulatory inactivation of DnaA and DNA replication.

    Science.gov (United States)

    Kawakami, Hironori; Su'etsugu, Masayuki; Katayama, Tsutomu

    2006-10-01

    In Escherichia coli, a complex consisting of Hda and the DNA-loaded clamp-subunit of the DNA polymerase III holoenzyme promotes hydrolysis of DnaA-ATP. The resultant ADP-DnaA is inactive for initiation of chromosomal DNA replication, thereby repressing excessive initiations. As the cellular content of the clamp is 10-100 times higher than that of Hda, most Hda molecules might be complexed with the clamp in vivo. Although Hda predominantly forms irregular aggregates when overexpressed, in the present study we found that co-overexpression of the clamp with Hda enhances Hda solubility dramatically and we efficiently isolated the Hda-clamp complex. A single molecule of the complex appears to consist of two Hda molecules and a single clamp. The complex is competent in DnaA-ATP hydrolysis and DNA replication in the presence of DNA and the clamp deficient subassembly of the DNA polymerase III holoenzyme (pol III*). These findings indicate that the clamp contained in the complex is loaded onto DNA through an interaction with the pol III* and that the Hda activity is preserved in these processes. The complex consisting of Hda and the DNA-unloaded clamp may play a specific role in a process proceeding to the DnaA-ATP hydrolysis in vivo.

  13. Essential and non-essential DNA replication genes in the model halophilic Archaeon, Halobacterium sp. NRC-1

    Directory of Open Access Journals (Sweden)

    DasSarma Shiladitya

    2007-06-01

    Full Text Available Abstract Background Information transfer systems in Archaea, including many components of the DNA replication machinery, are similar to those found in eukaryotes. Functional assignments of archaeal DNA replication genes have been primarily based upon sequence homology and biochemical studies of replisome components, but few genetic studies have been conducted thus far. We have developed a tractable genetic system for knockout analysis of genes in the model halophilic archaeon, Halobacterium sp. NRC-1, and used it to determine which DNA replication genes are essential. Results Using a directed in-frame gene knockout method in Halobacterium sp. NRC-1, we examined nineteen genes predicted to be involved in DNA replication. Preliminary bioinformatic analysis of the large haloarchaeal Orc/Cdc6 family, related to eukaryotic Orc1 and Cdc6, showed five distinct clades of Orc/Cdc6 proteins conserved in all sequenced haloarchaea. Of ten orc/cdc6 genes in Halobacterium sp. NRC-1, only two were found to be essential, orc10, on the large chromosome, and orc2, on the minichromosome, pNRC200. Of the three replicative-type DNA polymerase genes, two were essential: the chromosomally encoded B family, polB1, and the chromosomally encoded euryarchaeal-specific D family, polD1/D2 (formerly called polA1/polA2 in the Halobacterium sp. NRC-1 genome sequence. The pNRC200-encoded B family polymerase, polB2, was non-essential. Accessory genes for DNA replication initiation and elongation factors, including the putative replicative helicase, mcm, the eukaryotic-type DNA primase, pri1/pri2, the DNA polymerase sliding clamp, pcn, and the flap endonuclease, rad2, were all essential. Targeted genes were classified as non-essential if knockouts were obtained and essential based on statistical analysis and/or by demonstrating the inability to isolate chromosomal knockouts except in the presence of a complementing plasmid copy of the gene. Conclusion The results showed that ten

  14. Modulation of mutagenesis in eukaryotes by DNA replication fork dynamics and quality of nucleotide pools

    Science.gov (United States)

    Waisertreiger, Irina S.-R.; Liston, Victoria G.; Menezes, Miriam R.; Kim, Hyun-Min; Lobachev, Kirill S.; Stepchenkova, Elena I.; Tahirov, Tahir H.; Rogozin, Igor B.; Pavlov, Youri. I.

    2014-01-01

    The rate of mutations in eukaryotes depends on a plethora of factors and is not immediately derived from the fidelity of DNA polymerases (Pols). Replication of chromosomes containing the anti-parallel strands of duplex DNA occurs through the copying of leading and lagging strand templates by a trio of Pols α, δ and ε, with the assistance of Pol ζ and Y-family Pols at difficult DNA template structures or sites of DNA damage. The parameters of the synthesis at a given location are dictated by the quality and quantity of nucleotides in the pools, replication fork architecture, transcription status, regulation of Pol switches, and structure of chromatin. The result of these transactions is a subject of survey and editing by DNA repair. PMID:23055184

  15. Fluctuations of pol I and fibrillarin contents of the nucleoli.

    Science.gov (United States)

    Hornáček, M; Kováčik, L; Mazel, T; Cmarko, D; Bártová, E; Raška, I; Smirnov, E

    2017-07-04

    Nucleoli are formed on the basis of ribosomal DNA (rDNA) clusters called Nucleolus Organizer Regions (NORs). Each NOR contains multiple genes coding for RNAs of the ribosomal particles. The prominent components of the nucleolar ultrastructure, fibrillar centers (FC) and dense fibrillar components (DFC), together compose FC/DFC units. These units are centers of rDNA transcription by RNA polymerase I (pol I), as well as the early processing events, in which an essential role belongs to fibrillarin. Each FC/DFC unit probably corresponds to a single transcriptionally active gene. In this work, we transfected human-derived cells with GFP-RPA43 (subunit of pol I) and RFP-fibrillarin. Following changes of the fluorescent signals in individual FC/DFC units, we found two kinds of kinetics: 1) the rapid fluctuations with periods of 2-3 min, when the pol I and fibrillarin signals oscillated in anti-phase manner, and the intensities of pol I in the neighboring FC/DFC units did not correlate. 2) fluctuations with periods of 10 to 60 min, in which pol I and fibrillarin signals measured in the same unit did not correlate, but pol I signals in the units belonging to different nucleoli were synchronized. Our data indicate that a complex pulsing activity of transcription as well as early processing is common for ribosomal genes.

  16. Transcription initiation complex structures elucidate DNA opening.

    Science.gov (United States)

    Plaschka, C; Hantsche, M; Dienemann, C; Burzinski, C; Plitzko, J; Cramer, P

    2016-05-19

    Transcription of eukaryotic protein-coding genes begins with assembly of the RNA polymerase (Pol) II initiation complex and promoter DNA opening. Here we report cryo-electron microscopy (cryo-EM) structures of yeast initiation complexes containing closed and open DNA at resolutions of 8.8 Å and 3.6 Å, respectively. DNA is positioned and retained over the Pol II cleft by a network of interactions between the TATA-box-binding protein TBP and transcription factors TFIIA, TFIIB, TFIIE, and TFIIF. DNA opening occurs around the tip of the Pol II clamp and the TFIIE 'extended winged helix' domain, and can occur in the absence of TFIIH. Loading of the DNA template strand into the active centre may be facilitated by movements of obstructing protein elements triggered by allosteric binding of the TFIIE 'E-ribbon' domain. The results suggest a unified model for transcription initiation with a key event, the trapping of open promoter DNA by extended protein-protein and protein-DNA contacts.

  17. Replication of UV-irradiated single-stranded DNA by DNA polymerase III holoenzyme of Escherichia coli: evidence for bypass of pyrimidine photodimers

    International Nuclear Information System (INIS)

    Livneh, Z.

    1986-01-01

    Replication of UV-irradiated circular single-stranded phage M13 DNA by Escherichia coli RNA polymerase (EC 2.7.7.6) and DNA polymerase III holoenzyme (EC 2.7.7.7) in the presence of single-stranded DNA binding protein yielded full-length as well as partially replicated products. A similar result was obtained with phage G4 DNA primed with E. coli DNA primase, and phage phi X174 DNA primed with a synthetic oligonucleotide. The fraction of full-length DNA was several orders of magnitude higher than predicted if pyrimidine photodimers were to constitute absolute blocks to DNA replication. Recent models have suggested that pyrimidine photodimers are absolute blocks to DNA replication and that SOS-induced proteins are required to allow their bypass. Our results demonstrate that, under in vitro replication conditions, E. coli DNA polymerase III holoenzyme can insert nucleotides opposite pyrimidine dimers to a significant extent, even in the absence of SOS-induced proteins

  18. RNA polymerase III transcription - regulated by chromatin structure and regulator of nuclear chromatin organization.

    Science.gov (United States)

    Pascali, Chiara; Teichmann, Martin

    2013-01-01

    RNA polymerase III (Pol III) transcription is regulated by modifications of the chromatin. DNA methylation and post-translational modifications of histones, such as acetylation, phosphorylation and methylation have been linked to Pol III transcriptional activity. In addition to being regulated by modifications of DNA and histones, Pol III genes and its transcription factors have been implicated in the organization of nuclear chromatin in several organisms. In yeast, the ability of the Pol III transcription system to contribute to nuclear organization seems to be dependent on direct interactions of Pol III genes and/or its transcription factors TFIIIC and TFIIIB with the structural maintenance of chromatin (SMC) protein-containing complexes cohesin and condensin. In human cells, Pol III genes and transcription factors have also been shown to colocalize with cohesin and the transcription regulator and genome organizer CCCTC-binding factor (CTCF). Furthermore, chromosomal sites have been identified in yeast and humans that are bound by partial Pol III machineries (extra TFIIIC sites - ETC; chromosome organizing clamps - COC). These ETCs/COC as well as Pol III genes possess the ability to act as boundary elements that restrict spreading of heterochromatin.

  19. First-passage problems in DNA replication: effects of template tension on stepping and exonuclease activities of a DNA polymerase motor

    International Nuclear Information System (INIS)

    Sharma, Ajeet K; Chowdhury, Debashish

    2013-01-01

    A DNA polymerase (DNAP) replicates a template DNA strand. It also exploits the template as the track for its own motor-like mechanical movement. In the polymerase mode it elongates the nascent DNA by one nucleotide in each step. However, whenever it commits an error by misincorporating an incorrect nucleotide, it can switch to an exonuclease mode. In the latter mode it excises the wrong nucleotide before switching back to its polymerase mode. We develop a stochastic kinetic model of DNA replication that mimics an in vitro experiment where single-stranded DNA, subjected to a mechanical tension F, is converted to double-stranded DNA by a single DNAP. The F-dependence of the average rate of replication, which depends on the rates of both polymerase and exonuclease activities of the DNAP, is in good qualitative agreement with the corresponding experimental results. We introduce nine novel distinct conditional dwell times of a DNAP. Using the method of first-passage times, we also derive the exact analytical expressions for the probability distributions of these conditional dwell times. The predicted F-dependences of these distributions are, in principle, accessible to single-molecule experiments. (paper)

  20. TRE5-A retrotransposition profiling reveals putative RNA polymerase III transcription complex binding sites on the Dictyostelium extrachromosomal rDNA element.

    Directory of Open Access Journals (Sweden)

    Thomas Spaller

    Full Text Available The amoeba Dictyostelium discoideum has a haploid genome in which two thirds of the DNA encodes proteins. Consequently, the space available for selfish mobile elements to expand without excess damage to the host genome is limited. The non-long terminal repeat retrotransposon TRE5-A maintains an active population in the D. discoideum genome and apparently adapted to this gene-dense environment by targeting positions ~47 bp upstream of tRNA genes that are devoid of protein-coding regions. Because only ~24% of tRNA genes are associated with a TRE5-A element in the reference genome, we evaluated whether TRE5-A retrotransposition is limited to this subset of tRNA genes. We determined that a tagged TRE5-A element (TRE5-Absr integrated at 384 of 405 tRNA genes, suggesting that expansion of the current natural TRE5-A population is not limited by the availability of targets. We further observed that TRE5-Absr targets the ribosomal 5S gene on the multicopy extrachromosomal DNA element that carries the ribosomal RNA genes, indicating that TRE5-A integration may extend to the entire RNA polymerase III (Pol III transcriptome. We determined that both natural TRE5-A and cloned TRE5-Absr retrotranspose to locations on the extrachromosomal rDNA element that contain tRNA gene-typical A/B box promoter motifs without displaying any other tRNA gene context. Based on previous data suggesting that TRE5-A targets tRNA genes by locating Pol III transcription complexes, we propose that A/B box loci reflect Pol III transcription complex assembly sites that possess a function in the biology of the extrachromosomal rDNA element.