Biochemical and Structural Basis for Controlling Chemical Modularity in Fungal Polyketide Biosynthesis.
Biochemical and Structural Basis for Controlling Chemical Modularity in Fungal Polyketide Biosynthesis.
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DOI：
10.1021/jacs.5b04520
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发表时间：
2015-08-12
影响因子：
15
通讯作者：
Tang Y
中科院分区：
文献类型：
--
作者：
Winter JM;Cascio D;Dietrich D;Sato M;Watanabe K;Sawaya MR;Vederas JC;Tang Y
迭代真菌聚酮合酶（IPKS）之间的模块化协作是产生聚酮天然产物结构多样性的重要机制。 PKS 间通讯和底物通道在很大程度上由接受 IPKS 模块中发现的起始单元酰基载体蛋白转酰基酶 (SAT) 结构域控制。在这里，我们使用 IPKS CazF 和 CazM 重建了毛壳菌素和毛壳菌素 azaphilone 天然产物的苯甲醛核心的模块化生物合成。我们的研究揭示了 CazM 的 SAT 结构域在选择性转移 CazF 高度还原的三酮化合物产物中的关键作用。相比之下，CazF 也产生且最终产物生物合成后期所需的氧化程度更高的三酮化合物不被 SAT 结构域识别。真菌 SAT 结构域的第一个 X 射线结构揭示了酰基单元选择性的结构基础，并通过 SAT 活性位点中的共价己酰基硫酯中间体突出显示。 SAT 结构域的晶体结构将使蛋白质工程努力能够混合和匹配不同的 IPKS 模块以生物合成新化合物。
Modular collaboration between iterative fungal polyketide synthases (IPKSs) is an important mechanism for generating structural diversity of polyketide natural products. Inter-PKS communication and substrate channeling are controlled in large by the starter unit acyl carrier protein transacylase (SAT) domain found in the accepting IPKS module. Here, we reconstituted the modular biosynthesis of the benzaldehyde core of the chaetoviridin and chaetomugilin azaphilone natural products using the IPKSs CazF and CazM. Our studies revealed a critical role of CazM's SAT domain in selectively transferring a highly reduced triketide product from CazF. In contrast, a more oxidized triketide that is also produced by CazF and required in later stages of biosynthesis of the final product is not recognized by the SAT domain. The structural basis for the acyl unit selectivity was uncovered by the first X-ray structure of a fungal SAT domain, highlighted by a covalent hexanoyl thioester intermediate in the SAT active site. The crystal structure of SAT domain will enable protein engineering efforts aimed at mixing and matching different IPKS modules for the biosynthesis of new compounds.