The REC41 gene of Saccharomyces cerevisiae: isolation and genetic analysis

Abstract

Recombination-deficient strains have been proven useful for the understanding of the genetic control of homologous recombination. As the genetic screens used to isolate recombination-deficient (rec⁻) yeast mutants have not been saturated, we sought to develop a simple colony color assay to identify mutants with low or elevated rates of recombination. Using this system we isolated a collection of rec⁻ mutants. We report the characterization of the REC41 gene identified in this way. REC41 is required for normal levels of interplasmid recombination and γ-ray induced mitotic interchromosomal recombination. The rec41-1 mutant failed to grow at 37°C. Microscopic analysis of plated cells showed that 45–50% of them did not form visible colonies at permissive temperature. Haploid cells of the rec41 mutant show the same γ-ray sensitivity as wild type ones. However, the diploid rec41 mutant shows γ-ray sensitivity which is comparable with heterozygous REC41/rec41-1 diploid cells. This fact indicates semidominance of the rec41-1 mutation. Diploid strains homozygous for the rec41 rad52 mutations had the same γ-ray sensitivity as single rad52 diploids and exhibited dramatically decreased growth rate. The expression of the HO gene does not lead to inviability of rec41 cells. The rec41 mutation has an effect on meiosis, likely meiotic recombination, even in the heterozygous state. We cloned the REC41 gene. Sequence analysis revealed that the REC41 gene is encoded by ORF YDR245w. Earlier, this ORF was attributed to MNN10, BED1, SLC2, CAX5 genes. Two multicopy plasmids with suppressers of the rec41-1 mutation (pm21 and pm32) were isolated. The deletion analysis showed that only DNA fragments with the CDC43 and HAC1 genes can partially complement the rec41-1 mutation.