The 3 '-> 5 ' exonucleases of DNA polymerases delta and epsilon and the 5 '-> 3 ' exonuclease Exo1 have major roles in postreplication mutation avoidance in Saccharomyces cerevisiae
Ht. Tran et al., The 3 '-> 5 ' exonucleases of DNA polymerases delta and epsilon and the 5 '-> 3 ' exonuclease Exo1 have major roles in postreplication mutation avoidance in Saccharomyces cerevisiae, MOL CELL B, 19(3), 1999, pp. 2000-2007
Replication fidelity is controlled by DNA polymerase proofreading and postr
eplication mismatch repair. We have genetically characterized the roles of
the 5'-->3' Exo1 and the 3'-->5' DNA polymerase exonucleases in mismatch re
pair in the yeast Saccharomyces cerevisiae by using various genetic backgro
unds and highly sensitive mutation detection systems that are based on long
and short homonucleotide runs. Genetic interactions were examined among DN
A polymerase epsilon (pol2-4) and delta (pol3-01) mutants defective in 3'--
>5' proofreading exonuclease, mutants defective in the 5'-->3' exonuclease
Exo1, and mismatch repair mutants (msh2, msh3, or msh6). These three exonuc
leases play an important role in mutation avoidance. Surprisingly, the muta
tion rate in an exo1 pol3-01 mutant was comparable to that in an msh2 pol3-
01 mutant, suggesting that they participate directly in postreplication mis
match repair as well as in other DNA metabolic processes.