Three-dimensional structure of human electron transfer flavoprotein to 2.1-angstrom resolution
Three-dimensional structure of human electron transfer flavoprotein to 2.1-angstrom resolution
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DOI：
10.1073/pnas.93.25.14355
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发表时间：
1996-12-10
影响因子：
11.1
通讯作者：
Kim, JJP
中科院分区：
文献类型：
--
作者：
Roberts, DL;Frerman, FE;Kim, JJP
哺乳动物电子转移黄素蛋白 (ETF) 是含有单当量黄素腺嘌呤二核苷酸 (FAD) 的异二聚体。它们在参与线粒体脂肪酸和氨基酸分解代谢的初级黄素蛋白脱氢酶与膜结合电子转移黄素蛋白泛醌氧化还原酶之间充当电子穿梭机。分辨率为 2.1 埃的人类 ETF 结构显示，ETF 分子由三个不同的结构域组成：两个结构域由 α 亚基组成，第三个结构域完全由 β 亚基组成。 α 亚基的 N 端部分与大部分 β 亚基具有相同的多肽折叠，在不存在任何序列同源性的情况下，FAD 位于两个亚基之间的缝隙中，大部分 PAD 分子位于 C 端α亚基的一部分。 ETF α亚基的所有已知序列与推定的 FixB 基因产物的比对表明，直接参与 FAD 结合的残基是保守的，PAD 异咯嗪环的 N5 和 α T266 的羟基侧链之间形成氢键，这表明为什么致病性突变 α T266M 会影响 II 型戊二酸血症患者的 ETF 活性。 FAD 的核糖基链的 4'-羟基与异咯嗪环的 N1 之间以及 α H286 与异咯嗪环的 C2-羰基氧之间的氢键可能在阴离子半醌的稳定化中发挥作用。根据中链酰基辅酶A脱氢酶的已知结构，我们假设了两种蛋白质对接的可能结构。
Mammalian electron transfer flavoproteins (ETF) are heterodimers containing a single equivalent of flavin adenine dinucleotide (FAD). They function as electron shuttles between primary flavoprotein dehydrogenases involved in mitochondrial fatty acid and amino acid catabolism and the membrane-bound electron transfer flavoprotein ubiquinone oxidoreductase. The structure of human ETF solved to 2.1-Angstrom resolution reveals that the ETF molecule is comprised of three distinct domains: two domains are contributed by the alpha subunit and the third domain is made up entirely by the beta subunit, The N-terminal portion of the alpha subunit end the majority of the beta subunit have identical polypeptide folds, in the absence of any sequence homology, FAD lies in a cleft between the two subunits, with most of the PAD molecule residing in the C-terminal portion of the alpha subunit. Alignment of all the known sequences for the ETF alpha subunits together with the putative FixB gene product shows that the residues directly involved in FAD binding are conserved, A hydrogen bond is formed between the N5 of the PAD isoalloxazine ring and the hydroxyl side chain of alpha T266, suggesting why the pathogenic mutation, alpha T266M, affects ETF activity in patients with glutaric acidemia type II. Hydrogen bonds between the 4'-hydroxyl of the ribityl chain of FAD and N1 of the isoalloxazine ring, and between alpha H286 and the C2-carbonyl oxygen of the isoalloxazine ring, may play a role in the stabilization of the anionic semiquinone. With the known structure of medium chain acyl-CoA dehydrogenase, we hypothesize a possible structure for docking the two proteins.