The essential DNA polymerases delta and epsilon are involved in repair of UV-damaged DNA in the yeast Saccharomyces cerevisiae.

We have studied the ability of yeast DNA polymerases to carry out repair of lesions caused by UV irradiation in Saccharomyces cerevisiae. By the analysis of postirradiation relative molecular mass changes in cellular DNA of different DNA polymerases mutant strains, it was established that mutations in DNA polymerases delta and epsilon showed accumulation of single-strand breaks indicating defective repair. Mutations in other DNA polymerase genes exhibited no defects in DNA repair.

Involvement of the RE V3 gene in the methylated base-excision repair system. Co-operation of two DNA polymerases, delta and Rev3p, in the repair of MMS-induced lesions in the DNA of Saccharomyces cerevisiae.

The ability of four yeast DNA polymerase mutant strains to carry out the repair of DNA treated with MMS was studied. Mutation in DNA polymerase Rev3, as well as the already known mutation in the catalytic subunit of DNA polymerase delta, were both found to lead to the accumulation of single-strand breaks, which indicates defective repair. A double-mutant strain carrying mutations in DNA polymerase delta and a deletion in the REV3 gene had a complete repair defect, both at permissive (23 degrees C) and restrictive (38 degrees C) temperatures, which was not observed in other pairwise combinations of tested polymerase mutants.

Effects of the CDC2 gene on adaptive mutation in the yeast Saccharomyces cerevisiae.

We have studied the influence of a temperature-sensitive cdc2-1 mutation in DNA polymerase delta on the selection-induced mutation occurring at the LYS-2 locus in the yeast Saccharomyces cerevisiae. It was found that in cells plated on synthetic complete medium lacking only lysine, the numbers of Lys+ revertant colonies accumulated in a time-dependent manner in the absence of any detectable increase in cell number. When cdc2-1 mutant cells, after selective plating, were incubated at the restrictive temperature of 37 degrees C for 5 h daily for 7 days, the frequency of an adaptive reversion of lys(-)-->Lys+ was significantly higher than the frequency in cells incubated only at the permissive temperature, or in wild-type cells incubated either at 23 degrees C or 37 degrees C.

DNA polymerase III is required for DNA repair in Saccharomyces cerevisiae.

We have studied the role of DNA polymerase III, encoded in S. cerevisiae by the CDC2 gene, in the repair of yeast nuclear DNA. It was found that the repair of MMS-induced single-strand breaks is defective in the DNA polymerase III temperature-sensitive mutant cdc2-1 at the restrictive temperature (37 degrees C), but is not affected at the permissive temperature (23 degrees C).

Role of the CDC8 gene in the repair of single strand breaks in DNA of the yeast Saccharomyces cerevisiae.

It has been found that the repair of single strand breaks is defective in the DNA replication mutants cdc8-1 and cdc8-3 of Saccharomyces cerevisiae both in permissive (23 degrees C) and restrictive conditions (36 degrees C). In permissive conditions we observed a significant delay in single strand break repair in a diploid strain HB7 (cdc8-1/cdc8-1), as compared with the wild-type strain. Under restrictive conditions no repair was observed, but rather degradation of MMS-damaged DNA occurred.