3'-]5'-EXONUCLEASES OF DNA-POLYMERASE-EPSILON AND DNA-POLYMERASE-DELTA CORRECT BASE ANALOG INDUCED DNA-REPLICATION ERRORS ON OPPOSITE DNA STRANDS IN SACCHAROMYCES-CEREVISIAE
Pv. Shcherbakova et Yi. Pavlov, 3'-]5'-EXONUCLEASES OF DNA-POLYMERASE-EPSILON AND DNA-POLYMERASE-DELTA CORRECT BASE ANALOG INDUCED DNA-REPLICATION ERRORS ON OPPOSITE DNA STRANDS IN SACCHAROMYCES-CEREVISIAE, Genetics, 142(3), 1996, pp. 717-726
The base analog 6-N-hydroxylaminopurine (HAP) induces bidirectional GC
--> AT and AT --> GC transitions that are enhanced in DNA polymerase
epsilon and delta 3' --> 5' exonuclease-deficient yeast mutants, pol2-
4 and pol3-01, respectively. We have constructed a set of isogenic str
ains to determine whether the DNA polymerases delta and epsilon contri
bute equally to proofreading of replication errors provoked by HAP dur
ing leading and lagging strand DNA synthesis. Site-specific GC --> AT
and AT --> GC transitions in a Pol(+), pol2-4 or pol3-01 genetic backg
round were scored as reversions of ura3 missense alleles. At each site
, reversion was increased in only one proofreading-deficient mutant, e
ither pol2-4 or pol3-01, depending on the DNA strand in which HAP inco
rporation presumably occurred. Measurement of the HAP-induced reversio
n frequency of the ura3 alleles placed into chromosome III near to the
defined active replication origin ARS306 in two orientations indicate
d that DNA polymerases epsilon and delta correct HAP-induced DNA repli
cation errors on opposite DNA strands.