DNA polymerase λ can elongate on DNA substrates mimicking non-homologous end joining and interact with XRCC4-ligase IV complex
DNA polymerase λ can elongate on DNA substrates mimicking non-homologous end joining and interact with XRCC4-ligase IV complex
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DOI：
10.1016/j.bbrc.2004.09.002
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发表时间：
2004-10-29
影响因子：
3.1
通讯作者：
Wu, XM
中科院分区：
文献类型：
--
作者：
Fan, W;Wu, XM
非同源末端连接（NHEJ）是真核细胞中负责修复双链断裂的两种途径之一。该机制涉及以最小同源性对齐断裂的DNA末端，通过DNA聚合酶填充短缺口，以及通过XRCC 4-DNA连接酶IV复合物连接。间隙填充聚合酶尚未被确定，但最近的生物化学研究表明，DNA聚合酶λ（pol λ），一种新的DNA聚合酶，已被分配到pol X家族，在这个过程中。在这里，我们证明了纯化的聚合物λ可以有效地催化缺口填充合成的DNA底物模仿NHEJ。通过设计两种截短形式的pol λ，我们还表明，独特的脯氨酸丰富的区域在pol λ中发挥作用，限制链置换合成，一个功能，可能有助于其参与体内NHEJ。此外，pol λ通过其N-末端BRCT结构域与XRCC 4-DNA连接酶IV相互作用，并且这种相互作用刺激pol λ的DNA合成活性。总之，这些数据强烈支持pol lambda在NHEJ期间的DNA聚合事件中起作用。(C)2004年爱思唯尔公司All rights reserved.
Non-homologous end joining (NHEJ) is one of two pathways responsible for the repair of double-strand breaks in eukaryotic cells. The mechanism involves the alignment of broken DNA ends with minimal homology, fill in of short gaps by DNA polymerase(s), and ligation by XRCC4-DNA ligase IV complex. The gap-filling polymerase has not yet been positively identified, but recent biochemical studies have implicated DNA polymerase lambda (pol lambda), a novel DNA polymerase that has been assigned to the pol X family, in this process. Here we demonstrate that purified pol lambda can efficiently catalyze gap-filling synthesis on DNA substrates mimicking NHEJ. By designing two truncated forms of pol lambda, we also show that the unique proline-rich region in pol lambda plays a role in limiting strand displacement synthesis, a feature that may help its participation in in vivo NHEJ. Moreover, pol lambda interacts with XRCC4-DNA ligase IV via its N-terminal BRCT domain and the interaction stimulates the DNA synthesis activity of pol lambda. Taken together, these data strongly support that pol lambda functions in DNA polymerization events during NHEJ. (C) 2004 Elsevier Inc. All rights reserved.