探討酵母菌Pep4蛋白質分解酵素在減數分裂時對DNA重組的影響

Abstract

中文摘要 Pep4蛋白是位於酵母菌液泡的天門冬胺酸水解

Abstract Pep4 protein, a nonessential Saccharomyces cerevisiae vacuole aspartic protease, is indispensable for meiosis. Mutation or deletion of PEP4 gene leads to a cell cycle arrest before the first meiotic nuclear division. In addition, Pep4 protein and its proteolytic activity both are up-regulated during early meiosis. The latter has seriously impeded previous meiosis studies using biochemistry or proteomic approach. Hence, it is intriguing, probably also important, to understand the function of Pep4 protein during meiosis. Here we report that the pep4 mutant cell is defective in meiotic DNA recombination. Meiotic DNA recombination is initiated via formation of double strand breaks(DSBs), and subsequently produces recombinational products from the DNA of two parental homologous chromosomes. It had been shown previously that distribution of DSBs along the meiotic chromosomes is not random. Analysis of DSB hotspots revealed that the pep4 mutant produced normal levels of DSBs but almost no final recombination products. Intriguingly, the distribution of DSBs along meiotic chromosomes in the pep4 mutant was different from that of wild type cell. Our studies also indicated that several chromosome proteins were not properly degraded in the pep4 mutant during meiosis. We proposed that accumulation of superfluous chromosome proteins might influence structure of meiotic chromosomes and subsequently alter the chromosome distribution of DSBs.