Crystal structure and DNA-binding property of the ATPase domain of bacterial mismatch repair endonuclease MutL from Aquifex aeolicus
Crystal structure and DNA-binding property of the ATPase domain of bacterial mismatch repair endonuclease MutL from Aquifex aeolicus
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DOI：
10.1016/j.bbapap.2017.06.024
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发表时间：
2017-09-01
影响因子：
3.2
通讯作者：
Yano, Takato
中科院分区：
文献类型：
--
作者：
Fukui, Kenji;Iino, Hitoshi;Yano, Takato
DNA错配修复（MMR）系统纠正主要由DNA复制错误产生的错配碱基。修复系统切除含有错误的单链区域，并使链的重新合成成为可能。在MMR的早期反应中，MutL核酸内切酶切割双链体的新合成/含错误的链以启动下游切除反应。MutL核酸内切酶由N-末端ATP酶和C-末端核酸内切酶结构域组成。在这项研究中，我们报告的晶体结构的MutL内切酶从Aquifex aeolicus的ATP酶结构域。该结构域的整体结构与人MutL同源物和大肠杆菌MutL相似，但大肠杆菌MutL的结构域与人MutL同源物和大肠杆菌MutL相似。coliMutL无内切酶活性。ATP酶结构域由两个亚结构域组成：N-末端ATP结合亚结构域和C-末端α/β夹心亚结构域。定点突变实验鉴定了与DNA相互作用的8个碱性氨基酸残基，它们分布在两个亚结构域之间，形成了一个DNA结合裂隙。ATP酶和核酸内切酶结构域之间的对接模拟为全长A. aeolicus MutL，满足我们以前的小角X射线散射分析结果。根据模型结构和进一步的实验结果，我们得出结论，在全长A。aeolicus MutL同时结合dsDNA分子。
DNA mismatch repair (MMR) system corrects mismatched bases that are generated mainly by DNA replication errors. The repair system excises the error-containing single-stranded region and enables the re-synthesis of the strand. In the early reactions of MMR, MutL endonuclease incises the newly-synthesized/error-containing strand of the duplex to initiate the downstream excision reaction. MutL endonuclease consists of the N-terminal ATPase and C-terminal endonuclease domains. In this study, we report the crystal structure of the ATPase domain of MutL endonuclease from Aquifex aeolicus. The overall structure of the domain was similar to those of human MutL homologs and Escherichia coil MutL, although E. coli MutL has no endonuclease activity. The ATPase domain was comprised of two subdomains: the N-terminal ATP-binding subdomain and the C-terminal alpha/beta sandwich subdomain. Site-directed mutagenesis experiment identified DNA-interacting eight basic amino acid residues, which were distributed across both the two subdomains and formed a DNA-binding cleft. Docking simulation between the structures of the ATPase and endonuclease domains generated a reliable model structure for the full-length A. aeolicus MutL, which satisfies our previous result of small-angle X-ray scattering analysis. On the basis of the model structure and further experimental results, we concluded that the two separate DNA binding sites in the full-length A. aeolicus MutL simultaneously bind a dsDNA molecule.