Three-dimensional structure of rat-liver acyl-CoA oxidase in complex with a fatty acid: insights into substrate-recognition and reactivity toward molecular oxygen.
Three-dimensional structure of rat-liver acyl-CoA oxidase in complex with a fatty acid: insights into substrate-recognition and reactivity toward molecular oxygen.
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DOI：
10.1093/jb/mvj088
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发表时间：
2006-04
影响因子：
2.7
通讯作者：
K. Tokuoka;Y. Nakajima;K. Hirotsu;I. Miyahara;Y. Nishina;K. Shiga;H. Tamaoki;C. Setoyama;H. Tojo;R. Miura
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文献类型：
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作者：
K. Tokuoka;Y. Nakajima;K. Hirotsu;I. Miyahara;Y. Nishina;K. Shiga;H. Tamaoki;C. Setoyama;H. Tojo;R. Miura
采用分子置换法对大鼠肝酰基辅酶A氧化酶-II（ACO-II）与C12-脂肪酸复合物的三维结构进行了解析。通过ACO-II与十二烷酰基-CoA的共结晶获得复合物的结晶形式。晶体复合物在活性位点的缝隙中只含有通过硫酯键水解形成的脂肪酸部分。每个亚基的整体二聚体结构和折叠模式基本上可与未复合的ACO-II重叠。活性位点包括FAD的黄素环、包含脂肪酰基部分的缝隙和相邻的氨基酸侧链，除了Glu 421之外是重叠保守的，Glu 421的羧酸基团倾斜以容纳脂肪酸。结合脂肪酸的羧基氧之一与Glu 421的酰胺氢（假定的催化碱）和FAD的核糖基2 '-羟基氢键合。这种氢键网络与酰基辅酶A脱氢酶中的底物识别/活化密切相关。C12-脂肪酸的结合模式表明，活性位点在底物结合时不关闭，但在整个催化过程中保持宽敞，从而保持氧化半反应中的氧可及性。
The three-dimensional structure of rat-liver acyl-CoA oxidase-II (ACO-II) in a complex with a C12-fatty acid was solved by the molecular replacement method based on the uncomplexed ACO-II structure. The crystalline form of the complex was obtained by cocrystallization of ACO-II with dodecanoyl-CoA. The crystalline complex possessed, in the active-site crevice, only the fatty acid moiety that had been formed through hydrolysis of the thioester bond. The overall dimeric structure and the folding pattern of each subunit are essentially superimposable on those of uncomplexed ACO-II. The active site including the flavin ring of FAD, the crevice embracing the fatty acyl moiety, and adjacent amino acid side chains are superimposably conserved with the exception of Glu421, whose carboxylate group is tilted away to accommodate the fatty acid. One of the carboxyl oxygens of the bound fatty acid is hydrogen-bonded to the amide hydrogen of Glu421, the presumed catalytic base, and to the ribityl 2'-hydroxyl group of FAD. This hydrogen-bonding network correlates well with the substrate recognition/activation in acyl-CoA dehydrogenase. The binding mode of C12-fatty acid suggests that the active site does not close upon substrate binding, but remains spacious during the entire catalytic process, the oxygen accessibility in the oxidative half-reaction thereby being maintained.