Double-strand break repair in yeast requires both leading and lagging strand DNA polymerases
Double-strand break repair in yeast requires both leading and lagging strand DNA polymerases
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DOI：
10.1016/s0092-8674(00)80554-1
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发表时间：
1999-02-05
期刊：
影响因子：
64.5
通讯作者：
Haber, JE
中科院分区：
文献类型：
--
作者：
Holmes, AM;Haber, JE
在对必需复制因子具有温度敏感性的突变株中，对酿酒酵母（Saccharomyces cerevisiae）中MAT位点由有丝分裂双链断裂（DSB）诱导的基因转换进行了分子水平的分析。持续性辅因子增殖细胞核抗原（PCNA）和复制因子C（RFC）即使在链侵入后仅合成30个核苷酸也是必需的。与PCNA相关的DNA聚合酶δ和ε对基因转换都很重要，尽管温度敏感型的Pol ε突变体比Pol δ突变体的影响更严重。令人惊讶的是，滞后链复制的突变体，即DNA聚合酶α（pol1 - 17）、DNA引发酶（pri2 - 1）和Rad27p（rad27Δ），即使在G1期阻滞的细胞中，也极大地抑制了DSB修复的完成。我们提出了一个由DSB诱导基因转换的新模型，在该模型中，链侵入产生一个修饰的复制叉，涉及从供体模板进行的前导链和滞后链合成。通过捕获DSB的另一端来终止复制。
Mitotic double-strand break (DSB)-induced gene conversion at MAT in Saccharomyces cerevisiae was analyzed molecularly in mutant strains thermosensitive for essential replication factors. The processivity cofactors PCNA and RFC are essential even to synthesize as little as 30 nucleotides following strand invasion. Both PCNA-associated DNA polymerases delta and epsilon are important for gene conversion, though a temperature-sensitive Pol epsilon mutant is more severe than one in Pol delta. Surprisingly, mutants of lagging strand replication, DNA polymerase alpha (pol1-17), DNA primase (pri2-1), and Rad27p (rad27 Delta) also greatly inhibit completion of DSB repair, even in G1-arrested cells. We propose a novel model for DSB-induced gene conversion in which a strand invasion creates a modified replication fork, involving leading and lagging strand synthesis from the donor template. Replication is terminated by capture of the second end of the DSB.