Differential effects of the mismatch repair genes MSH2 and MSH3 on homeologous recombination in Saccharomyces cerevisiae.
Differential effects of the mismatch repair genes MSH2 and MSH3 on homeologous recombination in Saccharomyces cerevisiae.
复制标题
错配修复基因 MSH2 和 MSH3 对酿酒酵母同源重组的不同影响。
DOI：
10.1007/pl00008619
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
Lahue,RS
中科院分区：
文献类型：
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作者：
Selva,EM;Maderazo,AB;Lahue,RS
酵母错配修复基因MSH2和MSH3的产物参与抑制同源（相异）DNA序列之间的遗传重组。在缺乏这些基因的菌株中，由于这种抑制作用的丧失，重复元件之间的同源重组率升高。在这项研究中，这些突变的影响进行了进一步分析，通过定量的有丝分裂homeoblasts重组作为交换，基因转换或异常事件在野生型，msh2，msh3和msh2 msh3突变株。当同源异型序列以一个方向的直接重复序列存在时，msh2、msh3和msh2 msh3菌株的交叉和基因转换率升高。msh 2 msh 3双突变体的增加幅度大于单突变体。当同源异型序列的顺序颠倒时，sh2突变再次导致了交叉和基因转换率的增加。然而，在anmsh3株，基因转换发生在较高的水平，但染色体间的交叉没有增加和染色体内的交叉相对于野生型减少。msh2 msh3双突变体在此方向上的行为与sh2单突变体相似。在突变株中，含有同源重复的对照株在很大程度上但并非完全不受影响，这表明同源重组的不匹配中间体具有特异性。在所有菌株中，极少数（<10%）重组体可归因于异常事件。这些结果表明，MSH2和MSH3可以发挥不同的功能，以控制homeostransactions。
The products of the yeast mismatch repair genesMSH2andMSH3participate in the inhibition of genetic recombination between homeologous (divergent) DNA sequences. In strains deficient for these genes, homeologous recombination rates between repeated elements are elevated due to the loss of this inhibition. In this study, the effects of these mutations were further analyzed by quantitation of mitotic homeologous recombinants as crossovers, gene conversions or exceptional events in wild-type,msh2,msh3andmsh2 msh3mutant strains. When homeologous sequences were present as a direct repeat in one orientation, crossovers and gene conversions were elevated inmsh2,msh3andmsh2 msh3strains. The increases were greater in themsh2 msh3double mutant than in either single mutant. When the order of the homeologous sequences was reversed, themsh2mutation again yielded increased rates of crossovers and gene conversions. However, in anmsh3strain, gene conversions occurred at higher levels but interchromosomal crossovers were not increased and intrachromosomal crossovers were reduced relative to wild type. Themsh2 msh3double mutant behaved like themsh2single mutant in this orientation. Control strains harboring homologous duplications were largely but not entirely unaffected in mutant strains, suggesting specificity for the mismatched intermediates of homeologous recombination. In all strains, very few (<10%) recombinants could be attributed to exceptional events. These results suggest thatMSH2andMSH3can function differentially to control homeologous exchanges.