阿维米提醇合成酶的结构和机制,这是一个产生高度紧张的6-6-3三环酒精的赛斯基烯循环酶
Matthew N Gaynes1, Kristin R Osika1, David W Christianson1
1Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States.
Biochemistry
|December 1, 2025
概括
阿维米提醇合成酶 (SaAS) 使用被困的水分子进行催化. 关键残留物的突变会破坏水的结合,改变产品的形成,并失去主要产品 - - 甲基醇.
科学领域:
- 酶学和结构生物学 酶学和结构生物学
- 自然产品生物合成 自然产品生物合成
- 烯循环酶机制 烯循环酶机制
背景情况:
- 来自*Streptomyces avermitilis*的阿维米提醇合成酶 (SaAS) 合成了一种压缩的6-6-3三环基醇醇,阿维米提醇.
- 反应通过一个双循环中间体,双循环基,涉及质子启动的抗马尔科夫尼科夫添加和转解.
- 一个小的产品,viridifloral,由马尔科夫尼科夫的补充产生的.
研究的目的:
- 调查SaAS的基质范围和金属离子依赖性.
- 为了阐明保存水分子在SaAS活性部位中的作用.
- 了解阿维维米托尔和维里迪佛罗拉形成的结构基础.
主要方法:
- 酶学测试以确定基质范围和金属离子要求.
- 结晶学以获得与催化中间体模拟复杂的SaAS结构.
- 位点定向的突变发生和结构-活性关系研究.
主要成果:
- 晶体结构揭示了SaAS活动部位中两个连续被困的水分子.
- 残留物T215的突变发生破坏了与关键水分子 (W1) 的结,导致其重新定位.
- 突变的T215V取消了阿弗米蒂醇的生产,同时增强了viridifloral和其他副产品的形成.
结论:
- 捕获的水分子对于SaAS.通过Avermitilol合成的高保真度至关重要.
- T215V突变改变了水分子W1的定位,有利于其他反应途径.
- 这凸显了特定的水蛋白相互作用在控制烯循环酶产品特异性的重要性.
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