Both RAD5-dependent and independent pathways are involved in DNA damage-associated sister chromatid exchange in budding yeast.
Both RAD5-dependent and independent pathways are involved in DNA damage-associated sister chromatid exchange in budding yeast.
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DOI：
10.3934/genet.2017.2.84
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
Sun M
中科院分区：
文献类型：
--
作者：
Fasullo MT;Sun M
姐妹染色单体是细胞暴露于DNA损伤后进行重组修复的首选底物。虽然一些药物直接导致双链断裂(DSB)，但另一些药物形成DNA碱基加合物，从而阻碍或阻碍DNA复制分叉。我们询问了哪些类型的DNA损伤可以刺激模板切换机制缺陷的芽期酵母突变株的姐妹染色单体交换，以及在暴露于强有力的重组蛋白后，与DNA损伤相关的姐妹染色单体交换是否需要增殖细胞核抗原多泛素化功能。我们测量了含有HIS3两个片段的酵母菌株在暴露于MMS、4-NQO、UV、X光和HO核酸内切酶诱导的DSB后的自发和DNA损伤相关的不等姐妹染色单体交换(USCE)。我们确定了模板转换途径中的其他基因，包括UBC13、MMS2、SGS1和Srs2是否对DNA损伤相关的姐妹染色单体交换是必需的。RAD5是紫外线、MMS和4-NQO暴露后DNA损伤相关姐妹染色单体交换所必需的，但对自发的、X射线相关的或HO内切酶诱导的姐妹姐妹染色单体交换不是必需的。UBC13、MMS2和SGS1是MMS和4NQO相关的姐妹染色单体交换所必需的，而紫外线相关的姐妹染色单体交换则不需要它们。在rad5突变体中，his3重组底物之间的DNA损伤相关重组在非同源重组中得到加强。这些结果表明，引起DSB的DNA损伤剂通过RAD5不依赖的机制刺激姐妹染色单体交换，而几种产生大量DNA加合物的强效药物通过多种依赖于RAD5的机制刺激姐妹染色单体交换。我们认为，发生在G2中的DSB相关重组是RAD5不依赖的。
Sister chromatids are preferred substrates for recombinational repair after cells are exposed to DNA damage. While some agents directly cause double-strand breaks (DSBs), others form DNA base adducts which stall or impede the DNA replication fork. We asked which types of DNA damage can stimulate SCE in budding yeast mutants defective in template switch mechanisms and whether PCNA polyubiquitination functions are required for DNA damage-associated SCE after exposure to potent recombinagens. We measured spontaneous and DNA damage-associated unequal sister chromatid exchange (uSCE) in yeast strains containing two fragments of his3 after exposure to MMS, 4-NQO, UV, X rays, and HO endonuclease-induced DSBs. We determined whether other genes in the pathway for template switching, including UBC13, MMS2, SGS1, and SRS2 were required for DNA damage-associated SCE. RAD5 was required for DNA damage-associated SCE after exposure to UV, MMS, and 4-NQO, but not for spontaneous, X-ray-associated, or HO endonuclease-induced SCE. While UBC13, MMS2, and SGS1 were required for MMS and 4NQO-associated SCE, they were not required for UV-associated SCE. DNA damage-associated recombination between his3 recombination substrates on non-homologous recombination was enhanced in rad5 mutants. These results demonstrate that DNA damaging agents that cause DSBs stimulate SCE by RAD5-independent mechanisms, while several potent agents that generate bulky DNA adducts stimulate SCE by multiple RAD5-dependent mechanisms. We suggest that DSB-associated recombination that occurs in G2 is RAD5-independent.