PCNA activates the MutLγ endonuclease to promote meiotic crossing over.
PCNA activates the MutLγ endonuclease to promote meiotic crossing over.
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DOI：
10.1038/s41586-020-2645-6
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发表时间：
2020-10
期刊：
影响因子：
64.8
通讯作者：
Hunter N
中科院分区：
文献类型：
--
作者：
Kulkarni DS;Owens SN;Honda M;Ito M;Yang Y;Corrigan MW;Chen L;Quan AL;Hunter N
在减数分裂期间，交叉重组连接同源染色体以指导它们的精确分离。有缺陷的交换会导致不育、流产和先天性疾病。因此，每对染色体通过指定然后高效地实现交叉的过程来获得至少一个交叉。在DNA水平上，交换是通过双霍利迪结（dHJ）中间体的形成和偏置分辨率来实现的。交叉解析的中心原则是通过将核酸酶切口靶向特定DNA链，在相对平面中解析两个霍利迪连接（HJ）。MutLγ复合物的核酸内切酶活性与交叉偏倚分离有关，但激活和指导链特异性切割的机制仍不清楚。在这里，我们表明，滑动钳，PCNA，是很重要的交叉偏置分辨率。用人酶进行的体外测定显示，hPCNA及其装载剂hRFC足以激活hMutLγ内切核酸酶。在这种情况下，hMutLγ进一步受到促交换因子hEXO1和hMutSγ的共依赖活性的刺激，后者结合HJ。hMutLγ还特异性结合多种分支DNA，包括HJ，但未观察到典型的解离酶活性，这意味着核酸内切酶切割邻近连接分支点以实现解离。在体内，我们表明芽殖酵母RFC促进MutLγ依赖性交换。此外，PCNA定位于沿着突触染色体的预期交叉位点。这些数据突出了交叉分辨率和DNA错配修复的起始步骤之间的相似性，并引发了减数分裂期间交叉特异性dHJ分辨率的新模型。
During meiosis, crossover recombination connects homologous chromosomes to direct their accurate segregation. Defective crossing over causes infertility, miscarriage and congenital disease. Accordingly, each pair of chromosomes attains at least one crossover through processes that designate and then implement crossing over with high efficiency. At the DNA level, crossing over is implemented through the formation and biased resolution of double-Holliday Junction (dHJ) intermediates. A central tenet of crossover resolution is that the two Holliday junctions (HJs) are resolved in opposite planes by targeting nuclease incisions to specific DNA strands. The endonuclease activity of the MutLγ complex has been implicated in crossover-biased resolution, but mechanisms that activate and direct strand-specific cleavage remain unknown. Here we show that the sliding clamp, PCNA, is important for crossover-biased resolution. In vitro assays with human enzymes reveal that hPCNA and its loader hRFC are sufficient to activate the hMutLγ endonuclease. In this context, hMutLγ is further stimulated by a co-dependent activity of pro-crossover factors hEXO1 and hMutSγ, the latter of which binds HJs. hMutLγ also specifically binds a variety of branched DNAs, including HJs, but canonical resolvase activity is not observed implying that the endonuclease incises adjacent to junction branch points to effect resolution. In vivo, we show that budding yeast RFC facilitates MutLγ-dependent crossing over. Furthermore, PCNA localizes to prospective crossover sites along synapsed chromosomes. These data highlight similarities between crossover-resolution and the initiation steps of DNA mismatch repair and evoke a novel model for crossover-specific dHJ resolution during meiosis.
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DOI：
10.1073/pnas.93.23.12896
发表时间：
1996-11-12
影响因子：
11.1
作者：
Cai, JS;Uhlmann, F;Hurwitz, J
通讯作者：
Hurwitz, J
影响因子：
--
作者：
Owens S;Tang S;Hunter N
通讯作者：
Hunter N
影响因子：
3.8
作者：
Manhart CM;Alani E
通讯作者：
Alani E
影响因子：
1.2
作者：
Grubb, Jennifer;Brown, M. Scott;Bishop, Douglas K.
通讯作者：
Bishop, Douglas K.
影响因子：
10.5
作者：
Benjamin, KR;Zhang, C;Herskowitz, I
通讯作者：
Herskowitz, I