Rattray A J, Symington L S
Department of Microbiology, Columbia University College of Physicians and Surgeons, New York, New York 10032.
Genetics. 1995 Jan;139(1):45-56. doi: 10.1093/genetics/139.1.45.
The genes in the RAD52 epistasis group of Saccharomyces cerevisiae are necessary for most mitotic and meiotic recombination events. Using an intrachromosomal inverted-repeat assay, we previously demonstrated that mitotic recombination of this substrate is dependent upon the RAD52 gene. In the present study the requirement for other genes in this epistasis group for recombination of inverted repeats has been analyzed, and double and triple mutant strains were examined for their epistatic relationships. The majority of recombination events are mediated by a RAD51-dependent pathway, where the RAD54, RAD55 and RAD57 genes function downstream of RAD51. Cells mutated in RAD55 or RAD57 as well as double mutants are cold-sensitive for inverted-repeat recombination, whereas a rad51 rad55 rad57 triple mutant is not. The RAD1 gene is not required for inverted-repeat recombination but is able to process spontaneous DNA lesions to produce recombinant products in the absence of RAD51. Furthermore, there is still considerably more recombination in rad1 rad51 mutants than in rad52 mutants, indicating the presence of another, as yet unidentified, recombination pathway.
酿酒酵母RAD52上位性组中的基因对于大多数有丝分裂和减数分裂重组事件是必需的。我们之前使用染色体内部反向重复序列分析方法证明，该底物的有丝分裂重组依赖于RAD52基因。在本研究中，分析了该上位性组中其他基因对于反向重复序列重组的需求，并检测了双突变体和三突变体菌株的上位性关系。大多数重组事件由RAD51依赖的途径介导，其中RAD54、RAD55和RAD57基因在RAD51的下游发挥作用。RAD55或RAD57突变的细胞以及双突变体对反向重复序列重组是冷敏感的，而rad51 rad55 rad57三突变体则不是。反向重复序列重组不需要RAD1基因，但在没有RAD51的情况下，RAD1能够处理自发的DNA损伤以产生重组产物。此外，rad1 rad51突变体中的重组仍然比rad52突变体中的重组多得多，这表明存在另一种尚未确定的重组途径。
