Structural and Functional Analysis of A-Type Ketoreductases from the Amphotericin Modular Polyketide Synthase
Structural and Functional Analysis of A-Type Ketoreductases from the Amphotericin Modular Polyketide Synthase
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DOI：
10.1016/j.str.2010.04.015
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发表时间：
2010-08-11
期刊：
影响因子：
5.7
通讯作者：
Keatinge-Clay, Adrian T.
中科院分区：
文献类型：
--
作者：
Zheng, Jianting;Taylor, Clint A.;Keatinge-Clay, Adrian T.
复杂的聚酮化合物的特征在于具有多个手性中心，这些手性中心具有羟基和烷基取代基。为了研究这些立构中心的设置机制，解决了几个高分辨率结构的酮还原酶（KR）结构域的第二个模块的阿替西霉素模块化聚酮合酶（PKS）。A型KR的第一次结构分析有助于揭示这些KR如何将聚酮中间体从B型KR使用的相反侧引导到其活性位点，从而产生具有相反立体化学的β-羟基。在不存在和存在的配体的情况下获得的结构的比较揭示了一个诱导适合的机制，是重要的催化。活性测定的突变体的KR从第一和第二模块的阿氏菌素PKS揭示了几个活性位点残基对催化和立体控制的相对贡献。总之，这些结果突出了通过KRs的活性位点工程对聚酮进行区域特异性修饰的可能性。
Complex polyketides are characterized by multiple chiral centers harboring hydroxyl and alkyl substituents. To investigate the mechanisms by which these stereocenters are set, several high-resolution structures of the ketoreductase (KR) domain from the second module of the amphotericin modular polyketide synthase (PKS) were solved. This first structural analysis of an A-type KR helps reveal how these KRs direct polyketide intermediates into their active sites from the side opposite that used by B-type KRs, resulting in a beta-hydroxyl group of opposite stereochemistry. A comparison of structures obtained in the absence and presence of ligands reveals an induced fit mechanism that is important for catalysis. Activity assays of mutants of KRs from the first and second modules of the amphotericin PKS reveal the relative contributions of several active site residues toward catalysis and stereo-control. Together, these results highlight the possibility of region-specific modification of polyketides through active site engineering of KRs.