Muris D F, Vreeken K, Schmidt H, Ostermann K, Clever B, Lohman P H, Pastink A
MGC, Department of Radiation Genetics and Chemical Mutagenesis, Leiden University, Wassenaarseweg 72, 2333 AL Leiden, The Netherlands.
Curr Genet. 1997 Mar;31(3):248-54. doi: 10.1007/s002940050202.
The Schizosaccharomyces pombe rhp51+, rad22+ and rhp54+ genes are homologous to RAD51, RAD52 and RAD54 respectively, which are indispensable in the recombinational repair of double-strand breaks (DSBs) in Saccharomyces cerevisiae. The rhp51Delta and rhp54Delta strains are extremely sensitive to ionizing radiation; the rad22Delta mutant turned out to be much less sensitive. Homologous recombination in these mutants was studied by targeted integration at the leu1-32 locus. These experiments revealed that rhp51Delta and rhp54Delta are equally impaired in the integration of plasmid molecules (15-fold reduction), while integration in the rad22Delta mutant is only reduced by a factor of two. Blot-analysis demonstrated that the majority of the leu+ transformants of the wild-type and rad22Delta strains have integrated one or more copies of the vector. Gene conversion events were observed in less than 10% of the transformants. Interestingly, the relative contribution of gene conversion events is much higher in a rhp51Delta and a rhp54Delta background. Meiotic recombination is hardly affected in the rad22Delta mutant. The rhp51Delta and rhp54Delta strains also show minor deficiencies in this type of recombination. The viability of spores is 46% in the rad22Delta strain and 27% in the rhp54Delta strain, as compared with wild-type cells. However, in the rhp51Delta mutant the spore viability is only 1.7%, suggesting an essential role for Rhp51 in meiosis. The function of Rhp51 and Rhp54 in damage repair and recombination resembles the role of Rad51 and Rad54 in S. cerevisiae. Compared with Rad52 from S. cerevisiae, Rad22 has a much less prominent role in the recombinational repair pathway in S. pombe.
粟酒裂殖酵母的rhp51+、rad22+和rhp54+基因分别与酿酒酵母中双链断裂（DSB）重组修复所必需的RAD51、RAD52和RAD54同源。rhp51Δ和rhp54Δ菌株对电离辐射极为敏感；而rad22Δ突变体的敏感性则低得多。通过在leu1-32位点的靶向整合研究了这些突变体中的同源重组。这些实验表明，rhp51Δ和rhp54Δ在质粒分子整合方面同样受损（降低了15倍），而rad22Δ突变体中的整合仅降低了两倍。印迹分析表明，野生型和rad22Δ菌株的大多数亮氨酸+转化体已整合了一个或多个载体拷贝。在不到10%的转化体中观察到基因转换事件。有趣的是，在rhp51Δ和rhp54Δ背景下，基因转换事件的相对贡献要高得多。减数分裂重组在rad22Δ突变体中几乎不受影响。rhp51Δ和rhp54Δ菌株在这种重组类型中也表现出轻微缺陷。与野生型细胞相比，rad22Δ菌株中孢子的存活率为46%，rhp54Δ菌株中为27%。然而，在rhp51Δ突变体中，孢子存活率仅为1.7%，这表明Rhp51在减数分裂中起重要作用。Rhp51和Rhp54在损伤修复和重组中的功能类似于酿酒酵母中Rad51和Rad54的作用。与酿酒酵母的Rad52相比，Rad22在粟酒裂殖酵母的重组修复途径中的作用要小得多。
