J Bacteriol, May 1998, p. 2292-2297, Vol. 180, No. 9
0021-9193/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
-14 Dominant Negative Rat DNA Polymerase
Mutator
Mutant Commits Errors during the Gap-Filling Step of Base Excision
Repair in Saccharomyces cerevisiae
andDepartments of Therapeutic Radiology 1 and Genetics, 2 Yale University School of Medicine, New Haven, Connecticut 06520
Received 30 October 1997/Accepted 23 February 1998
We demonstrated recently that dominant negative mutants of rat DNA
polymerase
(Pol
) interfere with repair of alkylation damage in
Saccharomyces cerevisiae. To identify the alkylation repair
pathway that is disrupted by the Pol
dominant negative mutants, we
studied the epistatic relationship of the dominant negative Pol
mutants to genes known to be involved in repair of DNA alkylation
damage in S. cerevisiae. We demonstrate that the rat Pol
mutants interfere with the base excision repair pathway in S. cerevisiae. In addition, expression of one of the Pol
dominant negative mutants, Pol
-14, increases the spontaneous mutation rate of S. cerevisiae whereas expression of
another Pol
dominant negative mutant, Pol
-TR, does not.
Expression of the Pol
-14 mutant in cells lacking APN1 activity does
not result in an increase in the spontaneous mutation rate. These
results suggest that gaps are required for mutagenesis to occur in the presence of Pol
-14 but that it is not merely the presence of a gap
that results in mutagenesis. Our results suggest that mutagenesis can
occur during the gap-filling step of base excision repair in vivo.
Dedicated to the memory of Franklin Hutchinson.
Present address: Vion Pharmaceuticals, Inc., New Haven, CT
06511.
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