[Role of the RAD57 gene in the repair of double-stranded DNA gaps in the yeast Saccharomyces cerevisiae].

The linearized plasmid with complementary (cohesive) ends was shown to restore the circular form in cells of the rad57 mutant with a lower efficiency than in Rad+ cells. This process proved to be cold-sensitive in mutant cells, in contrast to wild-type cells. When mutant cells were shifted from 23 up to 36 degrees C, the repair efficiency increased approximately 1.5 times. In most cases examined, the repair was not accompanied by the doublestrand gap repair within the break site and did not depend on temperature. Homology between chromosomal and plasmid DNA sequences in the break region and the presence of cohesive ends were shown to be essential for the repair of linearized plasmids with a double-strand gap in cells of the rad57 mutant. Degradation of cohesive ends of the linearized plasmid during its repair in rad57 cells is insignificant. Possible mechanisms of linearized plasmid repair in the rad57 mutant are proposed.