Biosynthesis of the enediyne antitumor antibiotic C-1027 involves a new branching point in chorismate metabolism
Biosynthesis of the enediyne antitumor antibiotic C-1027 involves a new branching point in chorismate metabolism
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DOI：
10.1073/pnas.0708750105
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发表时间：
2008-01-15
影响因子：
11.1
通讯作者：
Shen, Ben
中科院分区：
文献类型：
--
作者：
Van Lanen, Steven G.;Lin, Shuangjun;Shen, Ben
C-1027是一种烯二炔抗肿瘤抗生素，由四个不同的部分组成：烯二炔核心、脱氧氨基糖、β-氨基酸和苯并恶唑酸酯部分。我们现在表明，苯并恶唑酸酯部分是由分支酸通过两种酶的顺序作用-SgcD，2-氨基-2-脱氧异分支酸（ADIC）合酶和SgcG，铁-硫，FMN依赖性ADIC酶-产生3-烯醇基邻氨基苯甲酸（OPA），一种新的中间体在分支酸代谢。每种酶的功能阐明和催化特性进行了描述，包括光谱表征的产品和发展的基于荧光的测定动力学分析。SgcD与异分支酸（IC）合酶和4-氨基-4-脱氧分支酸（ADC）合酶一起作为邻氨基苯甲酸合酶组分I（ASI）同源物，缺乏ASI固有的丙酮酸裂解酶活性;然而，与IC和ADC合酶相反，SgcD保留了与ASI观察到的相同的分支酸胺化能力。通过SgcD和SgcG的串联作用将分支酸净转化为OPA明确地建立了分支酸代谢中的新分支点。
C-1027 is an enediyne antitumor antibiotic composed of four distinct moieties: an enediyne core, a deoxy aminosugar, a beta-amino acid, and a benzoxazolinate moiety. We now show that the benzoxazolinate moiety is derived from chorismate by the sequential action of two enzymes-SgcD, a 2-amino-2-deoxyisochorismate (ADIC) synthase and SgcG, an iron-sulfur, FMN-dependent ADIC dehydrogenase-to generate 3-enolpyruvoylanthranilate (OPA), a new intermediate in chorismate metabolism. The functional elucidation and catalytic properties of each enzyme are described, including spectroscopic characterization of the products and the development of a fluorescence-based assay for kinetic analysis. SgcD joins isochorismate (IC) synthase and 4-amino-4-deoxychorismate (ADC) synthase as anthranilate synthase component I (ASI) homologues that are devoid of pyruvate lyase activity inherent in ASI; yet, in contrast to IC and ADC synthase, SgcD has retained the ability to aminate chorismate identically to that observed for ASI. The net conversion of chorismate to OPA by the tandem action of SgcD and SgcG unambiguously establishes a new branching point in chorismate metabolism.