Structural analysis of arabinose-5-phosphate isomerase from Bacteroides fragilis and functional implications.
Structural analysis of arabinose-5-phosphate isomerase from Bacteroides fragilis and functional implications.
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脆弱拟杆菌阿拉伯糖 5-磷酸异构酶的结构分析及其功能意义。
DOI：
10.1107/s1399004714017052
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
Wilson,IanA
中科院分区：
文献类型：
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作者：
Chiu,HsiuJu;Grant,JoannaC;Farr,CarolL;Jaroszewski,Lukasz;Knuth,MarkW;Miller,MitchellD;Elsliger,MarcAndré;Deacon,AshleyM;Godzik,Adam;Lesley,ScottA;Wilson,IanA
以 1.7 Å 分辨率测定了来自脆弱拟杆菌 (bfAPI) 的阿拉伯糖-5-磷酸异构酶 (API) 的晶体结构，发现它是单域糖异构酶 (SIS) 的四聚体，其内源配体 CMP-Kdo（胞苷 5'-单磷酸-3-脱氧-d-甘露糖-辛基-2-乌洛糖酸）结合在活性位点。 API 在 Kdo 生物合成途径的第一步中催化 d-核酮糖 5-磷酸可逆异构化为 d-阿拉伯糖 5-磷酸。有趣的是，结合的 CMP-Kdo 既不是 API 催化反应的底物也不是产物，而是对应于 Kdo 生物合成途径中的最终产物，并且可能充当 bfAPI 的反馈抑制剂。每个单体的活性位点位于三个单体之间四聚体界面的表面裂缝中，由来自两个不同相邻单体的 His79 和 His186 以及富含 Ser/Thr 的区域组成，所有这些在 API 中都高度保守。结构和序列分析表明His79和His186可能在异构化反应中发挥重要的催化作用。因此，CMP-Kdo 模拟物可以作为 API 的有效且特异性抑制剂，并针对许多不同的细菌感染提供广泛的保护。
The crystal structure of arabinose-5-phosphate isomerase (API) from Bacteroides fragilis (bfAPI) was determined at 1.7 Å resolution and was found to be a tetramer of a single-domain sugar isomerase (SIS) with an endogenous ligand, CMP-Kdo (cytidine 5′-monophosphate-3-deoxy-d-manno-oct-2-ulosonate), bound at the active site. API catalyzes the reversible isomerization of d-ribulose 5-phosphate to d-arabinose 5-phosphate in the first step of the Kdo biosynthetic pathway. Interestingly, the bound CMP-Kdo is neither the substrate nor the product of the reaction catalyzed by API, but corresponds to the end product in the Kdo biosynthetic pathway and presumably acts as a feedback inhibitor for bfAPI. The active site of each monomer is located in a surface cleft at the tetramer interface between three monomers and consists of His79 and His186 from two different adjacent monomers and a Ser/Thr-rich region, all of which are highly conserved across APIs. Structure and sequence analyses indicate that His79 and His186 may play important catalytic roles in the isomerization reaction. CMP-Kdo mimetics could therefore serve as potent and specific inhibitors of API and provide broad protection against many different bacterial infections.