Structural and mechanistic insights into polyketide macrolactonization from polyketide-based affinity labels
Structural and mechanistic insights into polyketide macrolactonization from polyketide-based affinity labels
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DOI：
10.1038/nchembio822
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发表时间：
2006-10-01
影响因子：
14.8
通讯作者：
Fecik, Robert A.
中科院分区：
文献类型：
--
作者：
Giraldes, John W.;Akey, David L.;Fecik, Robert A.
聚酮化合物是一类具有重要临床性质的天然产物，包括抗生素、免疫抑制和抗癌活性。它们由聚酮酶（PKS）生物合成，PKS是模块化的多酶复合物，其依次缩合简单的羧酸衍生物（1）。在许多PKS中的最终反应涉及硫酯酶催化的线性链延长中间体的环化。由于PKS中的底物是由栓系酰基载体蛋白呈递的，因此通过扩散引入底物是有问题的，并且迄今为止还没有底物结合的I型PKS结构域结构的报道。我们描述了化学合成的聚酮基的亲和标记，共价修饰的活性位点丝氨酸的切除匹克罗霉素硫酯酶从委内瑞拉链霉菌。本文报道的亲和标记-吡克霉素硫酯酶加合物的晶体结构提供了重要的机理见解。这些结果表明，亲和标记可以是有价值的工具，了解多功能PKS内的各个步骤的机制，并指导合理的PKS结构域的组合生物合成工程。
Polyketides are a diverse class of natural products having important clinical properties, including antibiotic, immunosuppressive and anticancer activities. They are biosynthesized by polyketide synthases (PKSs), which are modular, multienzyme complexes that sequentially condense simple carboxylic acid derivatives(1). The final reaction in many PKSs involves thioesterase-catalyzed cyclization of linear chain elongation intermediates. As the substrate in PKSs is presented by a tethered acyl carrier protein, introduction of substrate by diffusion is problematic, and no substrate-bound type I PKS domain structure has been reported so far. We describe the chemical synthesis of polyketide- based affinity labels that covalently modify the active site serine of excised pikromycin thioesterase from Streptomyces venezuelae. Crystal structures reported here of the affinity label-pikromycin thioesterase adducts provide important mechanistic insights. These results suggest that affinity labels can be valuable tools for understanding the mechanisms of individual steps within multifunctional PKSs and for directing rational engineering of PKS domains for combinatorial biosynthesis.