PCNA ubiquitylation ensures timely completion of unperturbed DNA replication in fission yeast.
PCNA ubiquitylation ensures timely completion of unperturbed DNA replication in fission yeast.
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DOI：
10.1371/journal.pgen.1006789
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发表时间：
2017-05
期刊：
影响因子：
4.5
通讯作者：
Carr AM
中科院分区：
文献类型：
--
作者：
Daigaku Y;Etheridge TJ;Nakazawa Y;Nakayama M;Watson AT;Miyabe I;Ogi T;Osborne MA;Carr AM
增殖细胞核抗原在赖氨酸164上的泛素化是DNA损伤耐受所必需的。在许多生物中，增殖细胞核抗原在未经挑战的S期也泛素化，但其意义尚未确定。利用裂殖酵母，我们证明了在没有DNA损伤的情况下，增殖细胞核抗原的赖氨酸164泛素化有助于有效的DNA复制。增殖细胞核抗原泛素化缺失在晚期复制区表现最为强烈，并增加了复制间隙的频率。我们发现，在无干扰的复制过程中，泛素化增加了染色质相关的增殖细胞核抗原的比例，并增加了聚合酶δ与增殖细胞核抗原的免疫共沉淀，并提出泛素化作用延长了这些复制蛋白的染色质结合，从而通过介导缺口填充有效地完成了冈崎片段的合成。增殖细胞核抗原是一种高三聚体复合体，它夹住DNA，为DNA聚合酶和其他复制和修复酶提供滑动平台。在DNA修复的背景下，泛素对赖氨酸164上的增殖细胞核抗原的共价修饰进行了广泛的研究：在DNA复制过程中，它需要介导受损的模板碱基的旁路。以前的工作表明，在没有DNA损伤的情况下，增殖细胞核抗原在正常的S期被泛素修饰，但这种修饰的意义还没有被探索。在这里，我们表明，除了调节受损碱基的旁路，赖氨酸164泛素化在确保完成不受干扰的DNA复制方面发挥了作用。
PCNA ubiquitylation on lysine 164 is required for DNA damage tolerance. In many organisms PCNA is also ubiquitylated in unchallenged S phase but the significance of this has not been established. Using Schizosaccharomyces pombe, we demonstrate that lysine 164 ubiquitylation of PCNA contributes to efficient DNA replication in the absence of DNA damage. Loss of PCNA ubiquitylation manifests most strongly at late replicating regions and increases the frequency of replication gaps. We show that PCNA ubiquitylation increases the proportion of chromatin associated PCNA and the co-immunoprecipitation of Polymerase δ with PCNA during unperturbed replication and propose that ubiquitylation acts to prolong the chromatin association of these replication proteins to allow the efficient completion of Okazaki fragment synthesis by mediating gap filling. PCNA is a homotrimeric complex that clamps around the DNA to provide a sliding platform for DNA polymerases and other replication and repair enzymes. The covalent modification of PCNA by ubiquitin on lysine reside 164 has been extensively studied in the context of DNA repair: it is required to mediate the bypass of damaged template bases during DNA replication. Previous work has shown that PCNA is modified by ubiquitin during normal S phase in the absence of DNA damage, but the significance of this modification has not been explored. Here we show that, in addition to regulating bypass of damaged bases, lysine 164 ubiquitylation plays a role in ensuring the completion of unperturbed DNA replication.