CRYSTAL-STRUCTURE OF PSEUDOMONAS-MEVALONII HMG-COA REDUCTASE AT 3.0 ANGSTROM RESOLUTION
CRYSTAL-STRUCTURE OF PSEUDOMONAS-MEVALONII HMG-COA REDUCTASE AT 3.0 ANGSTROM RESOLUTION
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DOI：
10.1126/science.7792601
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发表时间：
1995-06-23
期刊：
影响因子：
56.9
通讯作者：
STAUFFACHER, CV
中科院分区：
文献类型：
--
作者：
LAWRENCE, CM;RODWELL, VW;STAUFFACHER, CV
哺乳动物胆固醇生物合成的限速步骤是由3-羟基-3-甲基戊二酰辅酶A （HMG-CoA）还原酶催化的，这是一种将HMG-CoA转化为甲羟酸盐的四电子氧化还原酶。采用多次同构置换法，在3.0埃分辨率下测定了mevalonii假单胞菌HMG-CoA还原酶的晶体结构。该结构揭示了一个紧密结合的二聚体，它将涉及底物结合和催化的保守残基聚集在亚基界面上。这些二聚体围绕三倍结晶轴排列，形成具有23点群对称的六聚体。差分傅里叶研究揭示了底物HMG-CoA和还原或氧化烟酰胺腺嘌呤二核苷酸[NAD(H)]的结合位点，并表明活性位点位于二聚体界面。HMG-CoA由一个不寻常的褶皱结构域结合，由一个中心的α螺旋组成，周围是一组由β薄片和α螺旋组成的三角形壁。NAD(H)由一个以反平行β结构为特征的结构域结合，该结构域定义了一类二核苷酸结合结构域。
The rate-limiting step in cholesterol biosynthesis in mammals is catalyzed by 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, a four-electron oxidoreductase that converts HMG-CoA to mevalonate. The crystal structure of HMG-CoA reductase from Pseudomonas mevalonii was determined at 3.0 angstrom resolution by multiple isomorphous replacement. The structure reveals a tightly bound dimer that brings together at the subunit interface the conserved residues implicated in substrate binding and catalysis. These dimers are packed about a threefold crystallographic axis, forming a hexamer with 23 point group symmetry. Difference Fourier studies reveal the binding sites for the substrates HMG-CoA and reduced or oxidized nicotinamide adenine dinucleotide [NAD(H)] and demonstrate that the active sites are at the dimer interfaces. The HMG-CoA is bound by a domain with an unusual fold, consisting of a central alpha helix surrounded by a triangular set of walls of beta sheets and alpha helices. The NAD(H) is bound by a domain characterized by an antiparallel beta structure that defines a class of dinucleotide-binding domains.