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Träfflista för sökning "WFRF:(Watts Nick) srt2:(2010-2014)"

Sökning: WFRF:(Watts Nick) > (2010-2014)

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1.
  • Nick McElhinny, Stephanie A, et al. (författare)
  • Abundant ribonucleotide incorporation into DNA by yeast replicative polymerases.
  • 2010
  • Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - 0027-8424 .- 1091-6490. ; 107:11, s. 4949-4954
  • Tidskriftsartikel (refereegranskat)abstract
    • Measurements of nucleoside triphosphate levels in Saccharomyces cerevisiae reveal that the four rNTPs are in 36- to 190-fold molar excess over their corresponding dNTPs. During DNA synthesis in vitro using the physiological nucleoside triphosphate concentrations, yeast DNA polymerase epsilon, which is implicated in leading strand replication, incorporates one rNMP for every 1,250 dNMPs. Pol delta and Pol alpha, which conduct lagging strand replication, incorporate one rNMP for every 5,000 or 625 dNMPs, respectively. Discrimination against rNMP incorporation varies widely, in some cases by more than 100-fold, depending on the identity of the base and the template sequence context in which it is located. Given estimates of the amount of replication catalyzed by Pols alpha, delta, and epsilon, the results are consistent with the possibility that more than 10,000 rNMPs may be incorporated into the nuclear genome during each round of replication in yeast. Thus, rNMPs may be the most common noncanonical nucleotides introduced into the eukaryotic genome. Potential beneficial and negative consequences of abundant ribonucleotide incorporation into DNA are discussed, including the possibility that unrepaired rNMPs in DNA could be problematic because yeast DNA polymerase epsilon has difficulty bypassing a single rNMP present within a DNA template.
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2.
  • Nick McElhinny, Stephanie A, et al. (författare)
  • Genome instability due to ribonucleotide incorporation into DNA
  • 2010
  • Ingår i: Nature Chemical Biology. - 1552-4450 .- 1552-4469. ; 6:10, s. 774-81
  • Tidskriftsartikel (refereegranskat)abstract
    • Maintaining the chemical identity of DNA depends on ribonucleotide exclusion by DNA polymerases. However, ribonucleotide exclusion during DNA synthesis in vitro is imperfect. To determine whether ribonucleotides are incorporated during DNA replication in vivo, we substituted leucine or glycine for an active-site methionine in yeast DNA polymerase ϵ (Pol ϵ). Ribonucleotide incorporation in vitro was three-fold lower for M644L and 11-fold higher for M644G Pol ϵ compared to wild-type Pol ϵ. This hierarchy was recapitulated in vivo in yeast strains lacking RNase H2. Moreover, the pol2-M644G rnh201Δ strain progressed more slowly through S phase, had elevated dNTP pools and generated 2-5-base-pair deletions in repetitive sequences at a high rate and in a gene orientation-dependent manner. The data indicate that ribonucleotides are incorporated during replication in vivo, that they are removed by RNase H2-dependent repair and that defective repair results in replicative stress and genome instability via DNA strand misalignment.
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3.
  • Williams, Jessica S, et al. (författare)
  • Proofreading of ribonucleotides inserted into DNA by yeast DNA polymerase ɛ.
  • 2012
  • Ingår i: DNA Repair. - 1568-7864 .- 1568-7856. ; 11:8, s. 649-656
  • Tidskriftsartikel (refereegranskat)abstract
    • We have investigated the ability of the 3' exonuclease activity of Saccharomyces cerevisiae DNA polymerase ɛ (Pol ɛ) to proofread newly inserted ribonucleotides (rNMPs). During DNA synthesis in vitro, Pol ɛ proofreads ribonucleotides with apparent efficiencies that vary from none at some locations to more than 90% at others, with rA and rU being more efficiently proofread than rC and rG. Previous studies show that failure to repair ribonucleotides in the genome of rnh201Δ strains that lack RNase H2 activity elevates the rate of short deletions in tandem repeat sequences. Here we show that this rate is increased by 2-4-fold in pol2-4 rnh201Δ strains that are also defective in Pol ɛ proofreading. In comparison, defective proofreading in these same strains increases the rate of base substitutions by more than 100-fold. Collectively, the results indicate that although proofreading of an 'incorrect' sugar is less efficient than is proofreading of an incorrect base, Pol ɛ does proofread newly inserted rNMPs to enhance genome stability.
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