复制压力下芽殖酵母 Rad53 连接前导链和滞后链 DNA 合成的机制。
A mechanism for Rad53 to couple leading- and lagging-strand DNA synthesis under replication stress in budding yeast.
机构信息
Institute for Cancer Genetics, Columbia University Irving Medical Center, New York, NY 10032.
Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY 10032.
出版信息
Proc Natl Acad Sci U S A. 2021 Sep 21;118(38). doi: 10.1073/pnas.2109334118.
In response to DNA replication stress, DNA replication checkpoint kinase Mec1 phosphorylates Mrc1, which in turn activates Rad53 to prevent the generation of deleterious single-stranded DNA, a process that remains poorly understood. We previously reported that lagging-strand DNA synthesis proceeds farther than leading strand in mutant cells defective in replication checkpoint under replication stress, resulting in the exposure of long stretches of the leading-strand templates. Here, we show that asymmetric DNA synthesis is also observed in and cells defective in replication checkpoint but, surprisingly, not in cells in which both DNA replication and checkpoint functions of Mrc1 are missing. Furthermore, depletion of either Mrc1 or its partner, Tof1, suppresses the asymmetric DNA synthesis in mutant cells. Thus, the DNA replication checkpoint pathway couples leading- and lagging-strand DNA synthesis by attenuating the replication function of Mrc1-Tof1 under replication stress.
在应对 DNA 复制压力时，DNA 复制检查点激酶 Mek1 磷酸化 Mrc1，进而激活 Rad53 以防止产生有害的单链 DNA，这个过程仍知之甚少。我们之前曾报道，在复制检查点有缺陷的突变细胞中，滞后链 DNA 合成的进展超过了领头链，从而导致领头链模板暴露了很长一段，这一过程在复制压力下仍未得到很好的理解。在这里，我们发现复制检查点有缺陷的细胞也会出现不对称 DNA 合成，但令人惊讶的是，在 Mrc1 的 DNA 复制和检查点功能都缺失的 细胞中，却没有出现这种现象。此外，Mrc1 或其伴侣 Tof1 的消耗也能抑制 突变细胞中的不对称 DNA 合成。因此，DNA 复制检查点途径通过在复制压力下减弱 Mrc1-Tof1 的复制功能来偶联领头链和滞后链 DNA 的合成。
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