Structure of the pyruvate dehydrogenase multienzyme complex E1 component from Escherichia coli at 1.85 Å resolution
Structure of the pyruvate dehydrogenase multienzyme complex E1 component from Escherichia coli at 1.85 Å resolution
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DOI：
10.1021/bi0118557
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发表时间：
2002-04-23
期刊：
影响因子：
2.9
通讯作者：
Furey, W
中科院分区：
文献类型：
--
作者：
Arjunan, P;Nemeria, N;Furey, W
来自大肠杆菌丙酮酸脱氢酶多酶复合物（PDHc）的重组二磷酸硫胺素依赖性El组分的晶体结构已在1.85埃的分辨率下确定。急诊coli PDHc E1组分E1 p是一种同二聚体酶，并以不对称单位与完整的二聚体一起结晶。每个E1 p亚基由三个结构域组成：N-末端、中间和C-末端，所有结构域都具有α/β折叠。功能性二聚体含有位于亚基之间的界面处的两个催化中心。ThDP辅因子以“V”构象结合在两个亚基之间的裂缝中（结合涉及N-末端和中间结构域），并且存在共同的ThDP结合折叠。辅因子被完全掩埋，因为只有C2原子可以通过活性位点裂缝从溶液中接近。显着的结构差异之间观察到个别域的E1 p相对于异源四聚体多酶复合物El组件上操作的支链底物。这些差异可能是负责报告的替代E1 p结合模式E2组件内的相应复合物。本文介绍了第一个结构的例子，一个功能性丙酮酸脱氢酶E1 p组件从任何物种。它还提供了第一个代表性的例子，为整个家庭的同源二聚体（α 2）E1多酶复合物的组成部分，并应作为这类酶的模型。
The crystal structure of the recombinant thiamin diphosphate-dependent El component from the Escherichia coli pyruvate dehydrogenase multienzyme complex (PDHc) has been determined at a resolution of 1.85 Angstrom. The E. coli PDHc E1 component E1p is a homodimeric enzyme and crystallizes with an intact dimer in an asymmetric unit. Each E1p subunit consists of three domains: N-terminal, middle, and C-terminal, with all having alpha/beta folds. The functional dimer contains two catalytic centers located at the interface between subunits. The ThDP cofactors are bound in the "V" conformation in clefts between the two subunits (binding involves the N-terminal and middle domains), and there is a common ThDP binding fold. The cofactors are completely buried, as only the C2 atoms are accessible from solution through the active site clefts. Significant structural differences are observed between individual domains of E1p relative to heterotetrameric multienzyme complex El components operating on branched chain substrates. These differences may be responsible for reported alternative E1p binding modes to E2 components within the respective complexes. This paper represents the first structural example of a functional pyruvate dehydrogenase E1p component from any species. It also provides the first representative example for the entire family of homodimeric (alpha2) E1 multienzyme complex components, and should serve as a model for this class of enzymes.