Suppression of a new allele of the yeast RAD52 gene by overexpression of RAD51, mutations in srs2 and ccr4, or mating-type heterozygosity.
Suppression of a new allele of the yeast RAD52 gene by overexpression of RAD51, mutations in srs2 and ccr4, or mating-type heterozygosity.
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通过 RAD51 过表达、srs2 和 ccr4 突变或交配型杂合性抑制酵母 RAD52 基因的新等位基因。
DOI：
10.1093/genetics/140.1.115
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发表时间：
1995
期刊：
影响因子：
3.3
通讯作者：
Schild,D
中科院分区：
文献类型：
--
作者：
Schild,D
酿酒酵母的RAD 52基因参与DNA损伤的重组修复以及有丝分裂和减数分裂重组。一个新的rad 52等位基因已经被分离出来，具有不寻常的特性。与rad 52的其他等位基因不同，该等位基因（rad 52 -20）被srs 2缺失部分抑制; srs 2突变通常仅抑制rad 6和rad 18突变。此外，虽然单倍体rad 52 -20株系对X射线非常敏感，但该等位基因纯合的二倍体仅对X射线轻微敏感，并进行正常的减数分裂和减数分裂重组。因为交配型纯合的rad 52 -20二倍体对X射线非常敏感，所以交配型杂合性抑制rad 52 -20。交配型杂合性抑制该等位基因，即使在单倍体，因为sir突变，这导致正常沉默交配型盒的表达，被确定在基因外回复突变的rad 52 -20。一个新的srs 2等位基因和转录调控基因ccr 4和caf 1的等位基因是rad 52 -20的其他基因外回复突变体。因为其他研究人员已经表明，RAD 51和RAD 52蛋白相互作用，在高拷贝数质粒上的RAD 51被测试，发现抑制rad 52 -20等位基因，但RAD 54，55和57没有抑制。RAD 51质粒不抑制rad 52 -1。rad 52 -20等位基因可以编码与RAD 51蛋白具有低亲和力结合的蛋白。为了测试所选择的回复突变体是否通过提高RAD 51的表达来抑制rad 52 -20，将整合的RAD 51-lacZ融合体遗传杂交到每个回复突变体中。因为没有回复突变体增加了RAD 51-lacZ的水平，回复突变体必须发挥其作用的一个或多个机制，不介导的RAD 51。
The RAD52 gene of Saccharomyces cerevisiae is involved both in the recombinational repair of DNA damage and in mitotic and meiotic recombination. A new allele of rad52 has been isolated that has unusual properties. Unlike other alleles of rad52, this allele (rad52-20) is partially suppressed by an srs2 deletion; srs2 mutations normally act to suppress only rad6 and rad18 mutations. In addition, although haploid rad52-20 strains are very X-ray sensitive, diploids homozygous for this allele are only slightly X-ray sensitive and undergo normal meiosis and meiotic recombination. Because rad52-20 diploids homozygous for mating type are very X-ray sensitive, mating-type heterozygosity is acting to suppress rad52-20. Mating-type heterozygosity suppresses this allele even in haploids, because sir mutations, which result in expression of the normally silent mating-type cassettes, were identified among the extragenic revertants of rad52-20. A new allele of srs2 and alleles of the transcriptional regulatory genes ccr4 and caf1 were among the other extragenic revertants of rad52-20. Because other researchers have shown that the RAD51 and RAD52 proteins interact, RAD51 on a high copy number plasmid was tested and found to suppress the rad52-20 allele, but RAD54, 55 and 57 did not suppress. The RAD51 plasmid did not suppress rad52-1. The rad52-20 allele may encode a protein that has low affinity binding to the RAD51 protein. To test whether the selected revertants suppressed rad52-20 by elevating the expression of RAD51, an integrated RAD51-lacZ fusion was genetically crossed into each revertant. Because none of the revertants increased the level of RAD51-lacZ, the revertants must exert their effect by one or more mechanisms that are not mediated by RAD51.