%0 Journal Article
%T Replicative DNA Polymerase ¦Ä but Not ¦Å Proofreads Errors in Cis and in Trans
%A Arthur H. Shockley
%A Carrie L. Flood
%A Gaobin Bao
%A Gina P. Rodriguez
%A Gray F. Crouse
%A Yoke Wah Kow
%J -
%D 2015
%R 10.1371/journal.pgen.1005049
%X It is now well established that in yeast, and likely most eukaryotic organisms, initial DNA replication of the leading strand is by DNA polymerase ¦Å and of the lagging strand by DNA polymerase ¦Ä. However, the role of Pol ¦Ä 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 ¦Å or Pol ¦Ä in diploid strains. We find that wild-type Pol ¦Å molecules cannot proofread errors created by proofreading-defective Pol ¦Å molecules, whereas Pol ¦Ä can not only proofread errors created by proofreading-defective Pol ¦Ä molecules, but can also proofread errors created by Pol ¦Å-defective molecules. These results suggest that any interruption in DNA synthesis on the leading strand is likely to result in completion by Pol ¦Ä and also explain the higher mutation rates observed in Pol ¦Ä-proofreading mutants compared to Pol ¦Å-proofreading defective mutants. For strains reverting via AT¡úGC, TA¡úGC, CG¡úAT, and GC¡úAT 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¡ä-terminal 8 oxoG, unlike a 3¡ä-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
%K DNA replication
%K Polymerases
%K DNA polymerase
%K Mutation
%K Carcinogenesis
%K Mutant strains
%K Yeast
%K Saccharomyces cerevisiae
%U https://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1005049