Mechanistic implications from structures of yeast alcohol dehydrogenase complexed with coenzyme and an alcohol.
Mechanistic implications from structures of yeast alcohol dehydrogenase complexed with coenzyme and an alcohol.
复制标题
DOI：
10.1016/j.abb.2015.12.009
复制
发表时间：
2016-02
影响因子：
3.9
通讯作者：
B. Plapp;H. Charlier;S. Ramaswamy
中科院分区：
文献类型：
--
作者：
B. Plapp;H. Charlier;S. Ramaswamy
酵母醇脱氢酶I是由347个氨基酸残基组成的同源四聚体，以NAD+为辅酶催化醇的氧化。在3.0 nm处确定了一种新的X射线结构，其中不对称二聚体的两个亚基结合辅酶和三氟乙醇。四聚体是一对背靠背的二聚体。亚基A具有闭合构象，并且可以代表具有适当几何形状的米氏络合物，用于辅酶和醇之间的氢化物转移，其中2，2，2-三氟乙醇的氧在2.1 μ m处连接到与Cys-43、Cys-153和His-66的经典四面体配位中的催化锌。亚基B具有开放构象，并且辅酶与来自辅酶结合结构域的氨基酸残基相互作用，但不与来自催化结构域的残基相互作用。辅酶似乎与开放构象结合和解离。亚基B中的催化锌与Cys-43、Cys-153、His-66和Glu-67的羧酸根具有交替的、反向的配位，而三氟乙醇的氧距离锌3.5 π。亚基B可能代表辅酶与醇结合后，构象变为闭合形式，醇氧与锌结合并置换Glu-67之前的机制中的中间体。
Yeast alcohol dehydrogenase I is a homotetramer of subunits with 347 amino acid residues, catalyzing the oxidation of alcohols using NAD+as coenzyme. A new X-ray structure was determined at 3.0 Å where both subunits of an asymmetric dimer bind coenzyme and trifluoroethanol. The tetramer is a pair of back-to-back dimers. Subunit A has a closed conformation and can represent a Michaelis complex with an appropriate geometry for hydride transfer between coenzyme and alcohol, with the oxygen of 2,2,2-trifluoroethanol ligated at 2.1 Å to the catalytic zinc in the classical tetrahedral coordination with Cys-43, Cys-153, and His-66. Subunit B has an open conformation, and the coenzyme interacts with amino acid residues from the coenzyme binding domain, but not with residues from the catalytic domain. Coenzyme appears to bind to and dissociate from the open conformation. The catalytic zinc in subunit B has an alternative, inverted coordination with Cys-43, Cys-153, His-66 and the carboxylate of Glu-67, while the oxygen of trifluoroethanol is 3.5 Å from the zinc. Subunit B may represent an intermediate in the mechanism after coenzyme and alcohol bind and before the conformation changes to the closed form and the alcohol oxygen binds to the zinc and displaces Glu-67.