Structural Basis for Novel Interactions between Human Translesion Synthesis Polymerases and Proliferating Cell Nuclear Antigen
Structural Basis for Novel Interactions between Human Translesion Synthesis Polymerases and Proliferating Cell Nuclear Antigen
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DOI：
10.1074/jbc.m809745200
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发表时间：
2009-04-17
影响因子：
4.8
通讯作者：
Sato, Mamoru
中科院分区：
文献类型：
--
作者：
Hishiki, Asami;Hashimoto, Hiroshi;Sato, Mamoru
翻译合成（TLS）是一种DNA损伤耐受机制，即使在存在受损DNA模板的情况下，也允许持续的DNA合成。哺乳动物具有多种专门用于TLS的DNA聚合酶，包括Pol eta、Pol iota和Pol kappa。这些酶对不同的病变表现出优先旁路。增殖细胞核抗原（PCNA）作为复制聚合酶Pol δ的滑动夹起作用，也与三种TLS聚合酶相互作用。尽管许多PCNA结合蛋白具有称为PCNA相互作用蛋白盒（PIP盒）的高度保守序列，但Pol eta、Pol iota和Pol kappa具有非典型的PIP盒序列。在DNA损伤后，PCNA的Lys-164被RAD 6-RAD 18复合物泛素化，这种泛素化被认为是TLS的促进因素。与此一致，这三种TLS聚合酶具有一个或两个泛素结合结构域，并通过与涉及非经典PIP盒和泛素结合结构域的泛素化PCNA相互作用被招募到复制叉。然而，目前还不清楚这些TLS聚合酶如何与PCNA相互作用。为了解决不同的TLS聚合酶和PCNA之间的相互作用的结构基础，我们确定了晶体结构的PCNA绑定到肽含有这些聚合酶的非经典PIP盒。我们发现，这三个PIP盒肽与PCNA以不同的方式相互作用，无论是从另一个和典型的PIP盒肽。特别是，Poliota的PIP盒采用了新颖的结构。此外，这些结构使我们能够推测这些TLS聚合酶如何与Lys-164-monoubiquitinated PCNA相互作用。我们的研究结果将提供线索，了解TLS聚合酶的优先招聘停滞叉的机制。
Translesion synthesis (TLS) is a DNA damage tolerance mechanism that allows continued DNA synthesis, even in the presence of damaged DNA templates. Mammals have multiple DNA polymerases specialized for TLS, including Pol eta, Pol iota, and Pol kappa. These enzymes show preferential bypass for different lesions. Proliferating cell nuclear antigen (PCNA), which functions as a sliding clamp for the replicative polymerase Pol delta, also interacts with the three TLS polymerases. Although many PCNA-binding proteins have a highly conserved sequence termed the PCNA-interacting protein box (PIP-box), Pol eta, Pol iota, and Pol kappa have a noncanonical PIP-box sequence. In response to DNA damage, Lys-164 of PCNA undergoes ubiquitination by the RAD6-RAD18 complex, and the ubiquitination is considered to facilitate TLS. Consistent with this, these three TLS polymerases have one or two ubiquitin binding domains and are recruited to replication forks via interactions with ubiquitinated PCNA involving the noncanonical PIP-box and ubiquitin binding domain. However, it is unclear how these TLS polymerases interact with PCNA. To address the structural basis for interactions between different TLS polymerases and PCNA, we determined crystal structures of PCNA bound to peptides containing the noncanonical PIP-box of these polymerases. We show that the three PIP-box peptides interact with PCNA in different ways, both from one another and from canonical PIP-box peptides. Especially, the PIP-box of Pol iota adopts a novel structure. Furthermore, these structures enable us to speculate how these TLS polymerases interact with Lys-164-monoubiquitinated PCNA. Our results will provide clues to understanding the mechanism of preferential recruitment of TLS polymerases to the stalled forks.