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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Structural basis for the one-pot formation of the diarylheptanoid scaffold by curcuminoid synthase from Oryza sativa
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Structural basis for the one-pot formation of the diarylheptanoid scaffold by curcuminoid synthase from Oryza sativa

机译：水稻中姜黄素合成酶一锅法形成二芳基庚烷骨架的结构基础

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摘要

Curcuminoid synthase (CUS) from Oryza sativa is a plant-specific type III polyketide synthase (PKS) that catalyzes the remarkable one-pot formation of the C_6-C_7-C_6 diarylheptanoid scaffold of bis-demethoxycurcumin, by the condensation of two molecules of 4-coumaroyl-CoA and one molecule of malonyl-CoA. The crystal structure of O. sativa CUS was solved at 2.5-A resolution, which revealed a unique, downward expanding active-site architecture, previously unidentified in the known type III PKSs. The large active-site cavity is long enough to accommodate the two C_6-C_3 coumaroyl units and one malonyl unit. Furthermore, the crystal structure indicated the presence of a putative nucleophilic water molecule, which forms hydrogen bond networks with Ser351-Asn142-H_2O-T_(yr207)-Glu202, neighboring the catalytic Cy_(s174) at the active-site center. These observations suggest that CUS employs unique catalytic machinery for the one-pot formation of the C_6-C_7-C_6 scaffold. Thus, CUS utilizes the nucleophilic water to terminate the initial, polyketide chain elongation at the diketide stage. Thioester bond cleavage of the enzyme-bound intermediate generates 4-coumaroyldiketide acid, which is then kept within the downward expanding pocket for subsequent decarboxylative condensation with the second 4-coumaroyl-CoA starter, to produce bisdemethoxycurcumin. The structure-based site-directed mutants, M265L and G274F, altered the substrate and product specificities to accept 4-hydroxyphenyl-propionyl-CoA as the starter to produce tetrahydrobisdemethoxy-curcumin. These findings not only provide a structural basis for the catalytic machinery of CUS but also suggest further strategies toward expanding the biosynthetic repertoire of the type III PKS enzymes.
机译：来自水稻的姜黄素合酶（CUS）是一种植物特异性的III型聚酮化合物合酶（PKS），它通过两个4分子的缩合反应催化双去甲氧基姜黄素的C_6-C_7-C_6二芳基庚烷骨架的显着一锅形成。 -香豆酰辅酶A和一分子丙二酰辅酶A。 O. sativa CUS的晶体结构以2.5A的分辨率解析，这揭示了独特的，向下扩展的活性位点结构，这在已知的III型PKS中是未知的。较大的活动位腔足够长，可以容纳两个C_6-C_3香豆酰基单元和一个丙二酰基单元。此外，晶体结构表明存在推定的亲核水分子，该分子与在活性位点中心催化Cy_（s174）相邻的Ser351-Asn142-H_2O-T_（yr207）-Glu202形成氢键网络。这些观察结果表明，CUS为C_6-C_7-C_6支架的一锅形成采用了独特的催化机制。因此，CUS利用亲核水在双酮化合物阶段终止了初始的聚酮化合物链伸长。酶结合中间体的硫酯键裂解生成4-香豆酰二酮酸，然后将其保留在向下扩展的囊袋中，以便随后与第二个4-香豆酰-CoA起始剂进行脱羧缩合，生成双去甲氧基姜黄素。基于结构的定点突变体M265L和G274F改变了底物和产物的特异性，以接受4-羟苯基-丙酰基-CoA作为起始剂来生产四氢双去甲氧基姜黄素。这些发现不仅为CUS的催化机制提供了结构基础，而且为扩大III型PKS酶的生物合成库提供了进一步的策略。

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    Hiroyuki Morita; Kiyofumi Wanibuchi; Hirohiko Nii; Ryohei Kato; Shigetoshi Sugio; Ikuro Abe;

  • 作者单位

    Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan;

    Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan;

    Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan;

    Biotechnology Laboratory, Mitsubishi Chemical Group Science and Technology Research Center Inc., 1000 Kamoshida, Aoba, Yokohama, Kanagawa 227-8502, Japan;

    Biotechnology Laboratory, Mitsubishi Chemical Group Science and Technology Research Center Inc., 1000 Kamoshida, Aoba, Yokohama, Kanagawa 227-8502, Japan;

    Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan;

  • 收录信息 美国《科学引文索引》(SCI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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