Access to PCNA by Srs2 and Elg1 Controls the Choice between Alternative Repair Pathways in Saccharomyces cerevisiae
Access to PCNA by Srs2 and Elg1 Controls the Choice between Alternative Repair Pathways in Saccharomyces cerevisiae
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DOI：
10.1128/mbio.00705-20
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发表时间：
2020-05-01
期刊：
影响因子：
6.4
通讯作者：
Kupiec, Martin
中科院分区：
文献类型：
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作者：
Arbel, Matan;Bronstein, Alex;Kupiec, Martin
在DNA复制过程中，当复制的DNA聚合酶遇到损伤或难以复制的区域时，可能会发生停滞。在这些情况下，持续合成因子PCNA在赖氨酸164处被泛素化，诱导DNA损伤耐受（DDT）机制，可以绕过DNA复制过程中遇到的损伤。PCNA也可以在相同的残基或在赖氨酸127处SUMO化。令人惊讶的是，pol 30-K164 R突变体比pol 30-KK 127，164 RR菌株对DNA损伤剂显示出更高程度的敏感性，不能修饰任何赖氨酸。在这里，我们表明，除了translesion合成和链转移DDT机制，另一种修复机制（“抢救重组”），从姐妹染色单体复制信息被抑制的招聘Srs 2 SUMO化的PCNA。过表达的Elg 1，PCNA卸载，或重组蛋白Rad 52允许其激活。我们剖析了这一途径的遗传要求，以及Srs 2和Elg 1之间的相互作用。重要意义PCNA，包围DNA维持DNA聚合酶的持续合成能力的环，被泛素和SUMO修饰。而泛素是绕过病变所需的DNA损伤耐受（DDT）的途径，我们在这里表明，SUMO化抑制另一种途径，补救重组。Srs 2解旋酶被募集至SUMO化的PCNA并阻止补救途径起作用。该途径可以通过过表达PCNA卸载器Elg 1或同源重组蛋白Rad 52来诱导。我们的研究结果强调了PCNA修饰在控制各种旁路和DNA修复机制中的作用。
During DNA replication, stalling can occur when the replicative DNA polymerases encounter lesions or hard-to replicate regions. Under these circumstances, the processivity factor PCNA gets ubiquitylated at lysine 164, inducing the DNA damage tolerance (DDT) mechanisms that can bypass lesions encountered during DNA replication. PCNA can also be SUMOylated at the same residue or at lysine 127. Surprisingly, pol30-K164R mutants display a higher degree of sensitivity to DNA-damaging agents than pol30-KK127,164RR strains, unable to modify any of the lysines. Here, we show that in addition to translesion synthesis and strand-transfer DDT mechanisms, an alternative repair mechanism ("salvage recombination") that copies information from the sister chromatid is repressed by the recruitment of Srs2 to SUMOylated PCNA. Overexpression of Elg1, the PCNA unloader, or of the recombination protein Rad52 allows its activation. We dissect the genetic requirements for this pathway, as well as the interactions between Srs2 and Elg1.IMPORTANCE PCNA, the ring that encircles DNA maintaining the processivity of DNA polymerases, is modified by ubiquitin and SUMO. Whereas ubiquitin is required for bypassing lesions through the DNA damage tolerance (DDT) pathways, we show here that SUMOylation represses another pathway, salvage recombination. The Srs2 helicase is recruited to SUMOylated PCNA and prevents the salvage pathway from acting. The pathway can be induced by overexpressing the PCNA unloader Elg1, or the homologous recombination protein Rad52. Our results underscore the role of PCNA modifications in controlling the various bypass and DNA repair mechanisms.