Ligation of newly replicated DNA controls the timing of DNA mismatch repair.
Ligation of newly replicated DNA controls the timing of DNA mismatch repair.
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DOI：
10.1016/j.cub.2020.12.018
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发表时间：
2021-03-22
期刊：
影响因子：
--
通讯作者：
Hombauer H
中科院分区：
文献类型：
--
作者：
Reyes GX;Kolodziejczak A;Devakumar LJPS;Kubota T;Kolodner RD;Putnam CD;Hombauer H
错配修复 (MMR) 通过识别和切除 DNA 复制错误来保障基因组稳定性。真核错配修复如何在体内靶向新复制的链尚未确定。体外重建的 MMR 反应针对含有预先存在的切口或间隙的链，这表明链不连续性可以充当辨别信号。另一个候选者是增殖细胞核抗原 (PCNA)，它装载在复制叉上，是激活 Mlh1-Pms1 核酸内切酶所必需的。在这里，我们发现酿酒酵母中 DNA 连接酶 I (Cdc9) 的过度表达会导致突变率升高、染色质结合 PCNA 水平增加以及作为 MMR 中间体的 Pms1 灶的积累，这表明复制相关切口的过早连接会干扰 MMR。我们发现酵母 Pms1 表达主要局限于 S 期，这与 MMR 和 DNA 复制之间的时间耦合一致。将 Pms1 表达限制在 G2/M 期会导致突变表型，在核酸外切酶 Exo1 不存在的情况下，这种突变表型会加剧。通过减少或延迟体内 Cdc9 连接酶活性，增加复制相关 DNA 切口的寿命，可以在很大程度上抑制这种突变表型。因此，Cdc9 规定了由瞬时 DNA 切口决定的 MMR 时间窗口，该切口以链特异性方式指导 Mlh1-Pms1。由于 DNA 切口出现在新合成的前导链和滞后链上，因此这些结果建立了一种将 MMR 靶向新合成 DNA 的通用机制，从而防止人类癌症发展中突变的积累。通过错配修复 (MMR) 机制纠正 DNA 复制错误需要区分亲本和子代 DNA 链。雷耶斯等人。提供证据表明 DNA 复制相关切口被用作 MMR 链辨别信号，并且 DNA 连接酶 I (Cdc9) 活性决定了 MMR 的时间窗口。
Mismatch repair (MMR) safeguards genome stability through recognition and excision of DNA replication errors. How eukaryotic MMR targets the newly replicated strand in vivo has not been established. MMR reactions reconstituted in vitro are directed to the strand containing a preexisting nick or gap, suggesting that strand discontinuities could act as discrimination signals. Another candidate is the proliferating cell nuclear antigen (PCNA) that is loaded at replication forks and is required for the activation of Mlh1-Pms1 endonuclease. Here, we discovered that overexpression of DNA ligase I (Cdc9) in Saccharomyces cerevisiae causes elevated mutation rates and increased chromatin-bound PCNA levels and accumulation of Pms1 foci that are MMR intermediates, suggesting that premature ligation of replication-associated nicks interferes with MMR. We showed that yeast Pms1 expression is mainly restricted to S phase, in agreement with the temporal coupling between MMR and DNA replication. Restricting Pms1 expression to the G2/M phase caused a mutator phenotype that was exacerbated in the absence of the exonuclease Exo1. This mutator phenotype was largely suppressed by increasing the lifetime of replication-associated DNA nicks, either by reducing or delaying Cdc9 ligase activity in vivo. Therefore, Cdc9 dictates a window of time for MMR determined by transient DNA nicks that direct the Mlh1-Pms1 in a strand-specific manner. Because DNA nicks occur on both newly synthesized leading and lagging strands, these results establish a general mechanism for targeting MMR to the newly synthesized DNA, thus preventing the accumulation of mutations that underlie the development of human cancer. The correction of DNA replication errors by the mismatch repair (MMR) machinery requires the discrimination between parental and daughter DNA strands. Reyes et al. provide evidence that DNA replication-associated nicks are used as MMR strand discrimination signals and that DNA ligase I (Cdc9) activity dictates a window of time for MMR.
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DOI：
10.1126/science.1210770
发表时间：
2011-12-23
期刊：
Science (New York, N.Y.)
影响因子：
--
作者：
Hombauer H;Srivatsan A;Putnam CD;Kolodner RD
通讯作者：
Kolodner RD
影响因子：
16.8
作者：
Goellner EM;Putnam CD;Graham WJ 5th;Rahal CM;Li BZ;Kolodner RD
通讯作者：
Kolodner RD
影响因子：
16
作者：
Ghodgaonkar, Medini Manohar;Lazzaro, Federico;Olivera-Pimentel, Maite;Artola-Boran, Mariela;Cejka, Petr;Reijns, Martin A.;Jackson, Andrew P.;Plevani, Paolo;Muzi-Falconi, Marco;Jiricny, Josef
通讯作者：
Jiricny, Josef
影响因子：
4.5
作者：
Buckland RJ;Watt DL;Chittoor B;Nilsson AK;Kunkel TA;Chabes A
通讯作者：
Chabes A
影响因子：
3.8
作者：
Goellner EM;Putnam CD;Kolodner RD
通讯作者：
Kolodner RD