Links between replication and recombination in Saccharomyces cerevisiae:: A hypersensitive requirement for homologous recombination in the absence of Rad27 activity
Links between replication and recombination in Saccharomyces cerevisiae:: A hypersensitive requirement for homologous recombination in the absence of Rad27 activity
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DOI：
10.1073/pnas.121075598
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发表时间：
2001-07-17
影响因子：
11.1
通讯作者：
Nicolas, A
中科院分区：
文献类型：
--
作者：
Debrauwère, H;Loeillet, S;Nicolas, A
酿酒酵母RAD27基因编码5‘-3’翻盖外切/内切酶，在冈崎片段成熟的DNA复制过程中起重要作用。遗传研究表明，RAD27对生长不是必需的，尽管RAD27 Delta突变体对温度敏感。此外，它们对烷基化试剂表现出更高的敏感性，增强了自发重组，以及重复的DNA不稳定性。RAD27 Delta突变赋予的条件性致死性表明，其他核酸酶(S)可以弥补RAD27的缺失。事实上，生化和遗传学分析表明，冈崎片段的加工可以通过其他酶活性或其他途径，如同源重组来确保。在这里，我们介绍了一种利用合成致死性试验来鉴定rad27 Delta菌株生存所需功能的筛查结果。总之，我们确认Rad52重组修复途径的所有基因都是rad27 Delta菌株在允许(23摄氏度)和半允许(30摄氏度)生长温度下生存所必需的。我们还发现，在有丝分裂中比减数分裂细胞中表型弱的几个点突变(rad50S，mre11S)和额外的基因缺失(com1/sae2，srs2)显示出与rad27 Delta的合成致死性，而rad59 Delta与rad27 Delta显示出协同效应。这项研究和以前的研究表明，同源重组是主要的，但不仅是，功能绕过复制缺陷的复制缺陷出现在缺乏Rad27蛋白的情况下。
The RAD27 gene of Saccharomyces cerevisiae encodes a 5 ' -3 ' flap exo/endonuclease, which plays an important role during DNA replication for Okazaki fragment maturation. Genetic studies have shown that RAD27 is not essential for growth, although rad27 Delta mutants are temperature sensitive. Moreover, they exhibit increased sensitivity to alkylating agents, enhanced spontaneous recombination, and repetitive DNA instability. The conditional lethality conferred by the rad27 Delta mutation indicates that other nuclease(s) can compensate for the absence of Rad27. indeed, biochemical and genetical analyses indicate that Okazaki fragment processing can be assured by other enzymatic activities or by alternative pathways such as homologous recombination. Here we present the results of a screen that makes use of a synthetic lethality assay to identify functions required for the survival of rad27 Delta strains. Altogether, we confirm that all genes of the Rad52 recombinational repair pathway are required for the survival of rad27 Delta strains at both permissive (23 degreesC) and semipermissive (30 degreesC) temperatures for growth. We also find that several point mutations that confer weaker phenotypes in mitotic than in meiotic cells (rad50S, mre11s) and additional gene deletions (com1/sae2, srs2) exhibit synthetic lethality with rad27 Delta and that rad59 Delta exhibits synergistic effects with rad27 Delta. This and previous studies indicate that homologous recombination is the primary, but not only, pathway that functions to bypass the replication defects that arise in the absence of the Rad27 protein.