Structural basis for substrate fatty acyl chain specificity - Crystal structure of human very-long-chain acyl-CoA dehydrogenase
Structural basis for substrate fatty acyl chain specificity - Crystal structure of human very-long-chain acyl-CoA dehydrogenase
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DOI：
10.1074/jbc.m709135200
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发表时间：
2008-04-04
影响因子：
4.8
通讯作者：
Kim, Jung-Ja P.
中科院分区：
文献类型：
--
作者：
McAndrew, Ryan P.;Wang, Yudong;Kim, Jung-Ja P.
极长链酰基辅酶A脱氢酶（VLCAD）是酰基辅酶A脱氢酶（ACADs）家族的成员。与作为可溶性同源四聚体的其他ACADs不同，VLCAD是与线粒体膜相关的同源二聚体。VLCAD还在C末端具有在其他ACADs中不存在的另外180个残基。我们已经确定了VLCAD与肉豆蔻酰辅酶A复合的晶体结构，通过共结晶获得，分辨率为1.91-A。VLCAD的N-末端类似于400个残基的总体折叠类似于可溶性ACADs（包括中链酰基辅酶A脱氢酶（MCAD））的折叠。新的C-末端结构域形成α-螺旋束，其垂直于两个N-末端螺旋结构域定位。结合底物/产物的脂肪酰基部分深深嵌入蛋白质内部;然而，C14-CoA配体的腺苷焦磷酸部分由于硫酯键的部分水解和CoA部分的高迁移率而无序。Glu-422相对于结合配体和FAD的C2-C3的位置证实Glu-422是催化碱。在MCAD中，Gln-95和Glu-99形成底物结合腔的基底。在VLCAD中，这些残基是甘氨酸（Gly-175和Gly-178），允许结合通道延伸额外的12埃，并允许底物酰基链长度长达24个碳结合。VLCAD缺陷是线粒体β-氧化的更常见缺陷之一，如果未被诊断，可能是致命的。这种结构使我们能够深入了解变异VLCAD基因型如何导致临床表型。
Very-long-chain acyl-CoA dehydrogenase (VLCAD) is a member of the family of acyl-CoA dehydrogenases (ACADs). Unlike the other ACADs, which are soluble homotetramers, VLCAD is a homodimer associated with the mitochondrial membrane. VLCAD also possesses an additional 180 residues in the C terminus that are not present in the other ACADs. We have determined the crystal structure of VLCAD complexed with myristoyl-CoA, obtained by co-crystallization, to 1.91-A resolution. The overall fold of the N-terminal similar to 400 residues of VLCAD is similar to that of the soluble ACADs including medium-chain acyl-CoA dehydrogenase (MCAD). The novel C-terminal domain forms an alpha-helical bundle that is positioned perpendicular to the two N-terminal helical domains. The fatty acyl moiety of the bound substrate/product is deeply imbedded inside the protein; however, the adenosine pyrophosphate portion of the C14-CoA ligand is disordered because of partial hydrolysis of the thioester bond and high mobility of the CoA moiety. The location of Glu-422 with respect to the C2-C3 of the bound ligand and FAD confirms Glu-422 to be the catalytic base. In MCAD, Gln-95 and Glu-99 form the base of the substrate binding cavity. In VLCAD, these residues are glycines (Gly-175 and Gly-178), allowing the binding channel to extend for an additional 12 angstrom and permitting substrate acyl chain lengths as long as 24 carbons to bind. VLCAD deficiency is among the more common defects of mitochondrial beta-oxidation and, if left undiagnosed, can be fatal. This structure allows us to gain insight into how a variant VLCAD genotype results in a clinical phenotype.