Characterization of the repeat-tract instability and mutator phenotypes conferred by a Tn3 insertion in RFC1, the large subunit of the yeast clamp loader.


Journal Article

The RFC1 gene encodes the large subunit of the yeast clamp loader (RFC) that is a component of eukaryotic DNA polymerase holoenzymes. We identified a mutant allele of RFC1 (rfc1::Tn3) from a large collection of Saccharomyces cerevisiae mutants that were inviable when present in a rad52 null mutation background. Analysis of rfc1::Tn3 strains indicated that they displayed both a mutator and repeat-tract instability phenotype. Strains bearing this allele were characterized in combination with mismatch repair (msh2Delta, pms1Delta), double-strand break repair (rad52), and DNA replication (pol3-01, pol30-52, rth1Delta/rad27Delta) mutations in both forward mutation and repeat-tract instability assays. This analysis indicated that the rfc1::Tn3 allele displays synthetic lethality with pol30, pol3, and rad27 mutations. Measurement of forward mutation frequencies in msh2Delta rfc1:Tn3 and pms1Delta rfc1:Tn3 strains indicated that the rfc1::Tn3 mutant displayed a mutation frequency that appeared nearly multiplicative with the mutation frequency exhibited by mismatch-repair mutants. In repeat-tract instability assays, however, the rfc1::Tn3 mutant displayed a tract instability phenotype that appeared epistatic to the phenotype displayed by mismatch-repair mutants. From these data we propose that defects in clamp loader function result in DNA replication errors, a subset of which are acted upon by the mismatch-repair system.

Full Text

Duke Authors

Cited Authors

  • Xie, Y; Counter, C; Alani, E

Published Date

  • February 1999

Published In

Volume / Issue

  • 151 / 2

Start / End Page

  • 499 - 509

PubMed ID

  • 9927446

Pubmed Central ID

  • 9927446

International Standard Serial Number (ISSN)

  • 0016-6731


  • eng

Conference Location

  • United States