The Schizosaccharomyces pombe rec16 Gene Product Regulates Multiple Meiotic Events

Previously isolated meiotic recombination (rec) mutants of Schizosaccharomyces pombe define 16 complementation groups. The rec genes cloned and sequenced to date reveal little amino acid sequence identity to other reported proteins. We examined the rec mutants for alterations in meiotic events other than recombination to gain insight into the rec gene functions and to assess whether they affect recombination directly or indirectly. While mutations in the rec6–12, 14, 15 and 19 genes appeared to affect only meiotic recombination, a mutation in rec16 delayed meiotic DNA synthesis and, in some instances, reduced its amount; mitotic DNA synthesis was not detectably altered, indicating that the rec16 effect is limited to meiosis. In the rec16 mutant some meiotically induced transcripts (e.g., rec7 and 15) were significantly reduced in abundance, whereas others (e.g., rec10 and exo1) were induced and degraded with normal timing and extent during meiosis, indicating that the rec16 mutation leaves the basic meiotic program intact. These results indicate that the rec genes other than rec16 have their primary effect on meiotic recombination. In contrast, the rec16 gene product is essential for normal meiotic replication, recombination, and induction of some transcripts. These meiotic events may be coupled via a dependence of recombination and transcription on replication or via a cascade of gene expression.