Reconstitution of a Type II Polyketide Synthase that Catalyzes Polyene Formation
Reconstitution of a Type II Polyketide Synthase that Catalyzes Polyene Formation
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DOI：
10.1002/anie.201709636
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发表时间：
2018-02-12
影响因子：
16.6
通讯作者：
Ohnishi, Yasuo
中科院分区：
文献类型：
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作者：
Du, Danyao;Katsuyama, Yohei;Ohnishi, Yasuo
虽然已知II型聚酮化合物脱氢酶（PKS）用于产生芳香族化合物，但是最近已经提出了一个遗传学上新的II型PKS亚家族来合成多烯结构。在这里，我们报告在体外分析这样一个II型PKS，IgaPKS的石杉酰胺生物合成。酮还原酶（Iga 13）和脱氢酶（Iga 16）显示分别催化β-酮基的还原和β-羟基的脱水，以形成反式双键。酰基载体蛋白（Iga 10）、酮合酶/链长因子复合物（Iga 11-Iga 12）、Iga 13和Iga 16与丙二酰和己酰-CoA和NADPH，接着KOH水解，导致形成四种不饱和羧酸（C-8、C-10、C-12和C-14），表明IgaPKS通过重复缩合、酮还原和脱水的循环以严格的立体特异性催化四烯形成。我们提出了“高度还原II型PKS亚家族”的多烯生产II型PKS。
While type II polyketide synthases (PKSs) are known for producing aromatic compounds, a phylogenetically new subfamily of type II PKSs have been recently proposed to synthesize polyene structures. Here we report in vitro analysis of such a type II PKS, IgaPKS for ishigamide biosynthesis. The ketoreductase (Iga13) and dehydratase (Iga16) were shown to catalyze the reduction of a beta-keto group and dehydration of a beta-hydroxy group, respectively, to form a trans double bond. Incubation of the acyl carrier protein (Iga10), the ketosynthase/chain length factor complex (Iga11-Iga12), Iga13 and Iga16 with malonyl and hexanoyl-CoAs and NADPH followed by KOH hydrolysis resulted in the formation of four unsaturated carboxylic acids (C-8, C-10, C-12, and C-14), indicating that IgaPKS catalyzes tetraene formation by repeating the cycle of condensation, keto-reduction and dehydration with strict stereo-specificity. We propose "highly reducing type II PKS subfamily" for the polyene-producing type II PKSs.