New mutations of SRM genes in Saccharomyces cerevisiae and certain characteristics of their phenotypic effects

The effects of the previously identified mutations in nuclear genes SRM8, S RM12, SRM15, and SRM17 on the maintenance of chromosomes and recombinant pl asmids in Saccharomyces cerevisiae cells and on cell sensitivity to ionizin g radiation were studied. The srm8 mutation caused an increase in spontaneo us chromosome loss in diploid cells. In yeast cells with the intact mitocho ndrial genome, all examined srm mutations decreased the mitotic stability o f a centromeric recombinant plasmid with the chromosomal ARS element. Mutat ions srm12, srm15, and srm17 also decreased the mitotic stability of a cent romereless plasmid containing the same ARS element, whereas the srm8 mutati on did not markedly affect the maintenance of this plasmid. Mutations srm8, srm12, and srm17 were shown to increase cell sensitivity to gamma -rays. T he SRM8 gene was mapped, cloned, and found to correspond to the open readin g frame YJLO76w in chromosome X.