Sister chromatids are preferred over homologs as substrates for recombinational repair in Saccharomyces cerevisiae.
Sister chromatids are preferred over homologs as substrates for recombinational repair in Saccharomyces cerevisiae.
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DOI：
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发表时间：
1992-10
期刊：
影响因子：
3.3
通讯作者：
Lisa C. Kadyk;Leland H. Hartwell
中科院分区：
文献类型：
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作者：
Lisa C. Kadyk;Leland H. Hartwell
构建了一株可同时选择同源重组和不等姐妹染色单体重组事件产物的酿酒酵母二倍体菌株。该菌株在G1或G2中同步，用X射线照射以诱导DNA损伤，并监测重组水平。G1组细胞修复重组性损伤主要是通过同源重组，而G2组细胞修复这种损伤主要是姐妹染色单体重组。我们发现，和其他人一样，G1二倍体对X射线损伤的致死效应比G2二倍体敏感得多，特别是在更高剂量的辐射下。对这种观察结果的可能解释如下：G2细胞比G1细胞有更多的潜在修复模板；G2细胞在DNA损伤后受到RAD9介导的G2延迟的保护；姐妹染色单体可能比同源染色体有更多的同源性。所有这些可能性都被适当的测试排除了。我们认为，由于姐妹染色单体之间的特殊关系，姐妹染色单体不仅比同源染色单体更适合作为重组修复的底物，而且比同源染色单体具有更强的修复DNA损伤的能力。
A diploid Saccharomyces cerevisiae strain was constructed in which the products of both homolog recombination and unequal sister chromatid recombination events could be selected. This strain was synchronized in G1 or in G2, irradiated with X-rays to induce DNA damage, and monitored for levels of recombination. Cells irradiated in G1 were found to repair recombinogenic damage primarily by homolog recombination, whereas those irradiated in G2 repaired such damage preferentially by sister chromatid recombination. We found, as have others, that G1 diploids were much more sensitive to the lethal effects of X-ray damage than were G2 diploids, especially at higher doses of irradiation. The following possible explanations for this observation were tested: G2 cells have more potential templates for repair than G1 cells; G2 cells are protected by the RAD9-mediated delay in G2 following DNA damage; sister chromatids may share more homology than homologous chromosomes. All these possibilities were ruled out by appropriate tests. We propose that, due to a special relationship they share, sister chromatids are not only preferred over homologous chromatids as substrates for recombinational repair, but have the capacity to repair more DNA damage than do homologs.