Solution structure and dynamics of the lipoic acid-bearing domain of human mitochondrial branched-chain α-keto acid dehydrogenase complex
Solution structure and dynamics of the lipoic acid-bearing domain of human mitochondrial branched-chain α-keto acid dehydrogenase complex
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DOI：
10.1074/jbc.m110952200
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发表时间：
2002-05-03
影响因子：
4.8
通讯作者：
Huang, TH
中科院分区：
文献类型：
--
作者：
Chang, CF;Chou, HT;Huang, TH
在这种线粒体多酶复合体中，支链α-酮酸脱氢酶复合体的转酰基酶(E_2)亚单位的含硫酰基结构域(LBD)在底物通道中起着核心作用。我们使用多维异核核磁共振技术来确定人类支链α-酮酸脱氢酶复合体(HbLBD)的LBD的结构和动力学。与α-酮酸脱氢酶家族其他成员的LBD类似，hbLBD的溶液结构是由两个四链反平行的β-折叠形成的扁平的β-桶。硫辛基赖氨酸(44)残基位于由尖锐的I型β转角和两个连接的β链4和5组成的β-发夹的顶端。由连接β-1和β2-链的表面环L1和硫辛基赖氨酸β-发夹形成的突出的V形凹槽构成功能口袋。我们进一步应用约化谱密度函数理论，从600 MHz下获得的N-15-T-1、N-15-T-2和(H-1-N-15)核Overhaser效应数据中提取了hbLBD的动态信息。结果表明，由L1环和Lys(44)β-转角组成的硫辛基赖氨酸区周围的残基具有高度的灵活性，而β-折叠S1似乎表现出缓慢的构象交换过程。
The lipoyl-bearing domain (LBD) of the transacylase (E2) subunit of the branched-chain alpha-keto acid dehydrogenase complex plays a central role in substrate channeling in this mitochondrial multienzyme complex. We have employed multidimensional heteronuclear NMR techniques to determine the structure and dynamics of the LBD of the human branched-chain alpha-keto acid dehydrogenase complex (hbLBD). Similar to LBD from other members of the alpha-keto acid dehydrogenase family, the solution structure of hbLBD is a flattened beta-barrel formed by two four-stranded antiparallel beta-sheets. The lipoyl Lys(44) residue resides at the tip of a beta-hairpin comprising a sharp type I beta-turn and the two connecting beta-strands 4 and 5. A prominent V-shaped groove formed by a surface loop, L1, connecting beta1- and beta2-strands and the lipoyl lysine beta-hairpin constitutes the functional pocket. We further applied reduced spectral density functions formalism to extract dynamic information of hbLBD from N-15-T-1, N-15-T-2, and (H-1-N-15) nuclear Overhauser effect data obtained at 600 MHz. The results showed that residues surrounding the lipoyl lysine region comprising the L1 loop and the Lys(44) beta-turn are highly flexible, whereas beta-sheet S1 appears to display a slow conformational exchange process.