Regulation of WRN helicase activity in human base excision repair
Regulation of WRN helicase activity in human base excision repair
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DOI：
10.1074/jbc.m409624200
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发表时间：
2004-12-17
影响因子：
4.8
通讯作者：
Bohr, VA
中科院分区：
文献类型：
--
作者：
Ahn, B;Harrigan, JA;Bohr, VA
Werner综合征患者缺乏Werner蛋白（WRN），Werner蛋白是一种多功能核蛋白，具有3 '-5'核酸外切酶和ATP依赖性解旋酶活性。Werner综合征细胞的研究和WRN的生化研究表明，WRN在几种DNA代谢途径中发挥作用。WRN与DNA聚合酶β（pol β）相互作用，并以解旋酶依赖性方式刺激碱基切除修复（BER）中间体上的pol β链置换合成。在这份报告中，我们研究了主要的人类脱嘌呤/脱嘧啶核酸内切酶（APE 1）和聚合酶β对WRN解旋酶活性的影响。结果表明，WRN单独能够解开几个单链断裂BER中间体。然而，APE 1抑制WRN解旋酶对这些中间体的活性。这种抑制作用可能是由于APE 1与有缺口的脱嘌呤/脱嘧啶位点的结合，表明APE 1阻止BER中间体的混杂解旋。这种抑制作用被pol β的存在所缓解。基于这些结果，提出了一个涉及pol β介导的WRN蛋白传递的模型。
Werner syndrome patients are deficient in the Werner protein (WRN), which is a multifunctional nuclear protein possessing 3'- 5' exonuclease and ATP-dependent helicase activities. Studies of Werner syndrome cells and biochemical studies of WRN suggest that WRN plays a role in several DNA metabolic pathways. WRN interacts with DNA polymerase beta(pol beta) and stimulates pol beta strand displacement synthesis on a base excision repair (BER) intermediate in a helicase-dependent manner. In this report, we examined the effect of the major human apurinic/apyrimidinic endonuclease (APE1) and of pol beta on WRN helicase activity. The results show that WRN alone is able to unwind several single strand break BER intermediates. However, APE1 inhibits WRN helicase activity on these intermediates. This inhibition is likely due to the binding of APE1 to nicked apurinic/apyrimidinic sites, suggesting that APE1 prevents the promiscuous unwinding of BER intermediates. This inhibitory effect was relieved by the presence of pol beta. A model involving the pol beta-mediated hand-off of WRN protein is proposed based on these results.