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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Structure And Dna Binding Of Alkylation Response Protein Aidb
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Structure And Dna Binding Of Alkylation Response Protein Aidb

机译：烷基化反应蛋白Aidb的结构和Dna结合

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摘要

Exposure of Escherichia coli to alkylating agents activates expression of AidB in addition to DNA repair proteins Ada, AlkA, and AlkB. AidB was recently shown to possess a flavin adenine dinucleotide (FAD) cofactor and to bind to dsDNA, implicating it as a flavin-dependent DNA repair enzyme. However, the molecular mechanism by which AidB acts to reduce the mutagenic effects of specific DNA alkylators is unknown. We present a 1.7-A crystal structure of AidB, which bears superficial resemblance to the acyl-CoA dehy-drogenase superfamily of flavoproteins. The structure reveals a unique quaternary organization and a distinctive FAD active site that provides a rationale for AidB's limited dehydrogenase activity. A highly electropositive C-terminal domain not present in structural homologs was identified by mutational analysis as the DNA binding site. Structural analysis of the DNA and FAD binding sites provides evidence against AidB-catalyzed DNA repair and supports a model in which AidB acts to prevent alkylation damage by protecting DNA and destroying alkylating agents that have yet to reach their DNA target.
机译：除了DNA修复蛋白Ada，AlkA和AlkB外，大肠杆菌暴露于烷基化剂还会激活AidB的表达。最近显示，AidB具有黄素腺嘌呤二核苷酸（FAD）辅因子并与dsDNA结合，暗示其为黄素依赖性DNA修复酶。但是，AidB降低特定DNA烷基化剂的诱变作用的分子机制尚不清楚。我们提出了AidB的1.7-A晶体结构，与黄素蛋白的酰基辅酶A脱氢酶超家族具有表面相似性。该结构揭示了独特的四级组织和独特的FAD活性位点，为AidB有限的脱氢酶活性提供了理论依据。通过突变分析鉴定出结构同源物中不存在的高度电阳性的C末端结构域为DNA结合位点。 DNA和FAD结合位点的结构分析为抗AidB催化的DNA修复提供了证据，并支持AidB通过保护DNA并破坏尚未达到其DNA靶点的烷基化剂来防止烷基化损伤的模型。

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