Structure and mechanism of the evolutionarily unique plant enzyme chalcone isomerase

被引：267

作者：

Jez J.M. ^{[1
]}

Bowman M.E. ^{[1
]}

Dixon R.A. ^{[2
]}

Noel J.P. ^{[1
]}

机构：

[1] Structural Biology Laboratory, Salk Inst. for Biological Studies, San Diego, CA 92037

[2] Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, OK 73402

来源：

Nature Structural Biology | 2000年 / 7卷 / 9期

基金：

美国国家卫生研究院; 美国国家科学基金会;

关键词：

D O I：

10.1038/79025

中图分类号：

学科分类号：

摘要：

Chalcone isomerase (CHI) catalyzes the intramolecular cyclization of chalcone synthesized by cholcone synthase (CHS) into (2S)-naringenin, an essential compound in the biosynthesis of anthocyanin pigments, inducers of Rhizobium nodulation genes, and antimicrobial phytoalexins. The 1.85 Å resolution crystal structure of alfalfa CHI in complex with (2S)-naringenin reveals a novel open-faced β-sandwich fold. Currently, proteins with homologous primary sequences are found only in higher plants. The topology of the active site cleft defines the stereochemistry of the cyclization reaction. The structure and mutational analysis suggest a mechanism in which shape complementarity of the binding cleft locks the substrate into a constrained conformation that allows the reaction to proceed with a second-order rate constant approaching the diffusion controlled limit. This structure raises questions about the evolutionary history of this structurally unique plant enzyme.

引用

页码：786 / 791

页数：5

共 42 条

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