Biosynthesis of Isoprenoids: Crystal Structure of the [4Fe-4S] Cluster Protein IspG
Biosynthesis of Isoprenoids: Crystal Structure of the [4Fe-4S] Cluster Protein IspG
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DOI：
10.1016/j.jmb.2010.09.050
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发表时间：
2010-12-10
影响因子：
5.6
通讯作者：
Groll, Michael
中科院分区：
文献类型：
--
作者：
Lee, Matthias;Graewert, Tobias;Groll, Michael
IspG蛋白是新近发现的非甲戊酸途径的倒数第二个酶，用于合成普遍存在的异戊二烯基二磷酸和二甲基烯丙基二磷酸。该酶催化2C-甲基-D-赤藓糖醇2，4-环二磷酸还原开环，生成1-羟基-2-甲基-2-(E)-丁烯基4-二磷酸。该蛋白质在厌氧条件下结晶，测定其三维结构，分辨率为2.7埃。C(2)对称同源二聚体的每个亚基折叠成由短连接序列连接的两个结构域。N-末端结构域(N结构域)是一个八链的β-桶，属于大的Tim-Barrel超家族。C-末端结构域(C结构域)由两侧由螺旋组成的β片层组成。C结构域的一个谷氨酸和三个半胱氨酸残基配位着一个[4Fe-4S]簇。同源二聚体的形成涉及每个相应β桶的螺旋8和9之间的扩展接触区域(约1100埃(2))。此外，每个C结构域都与伙伴亚基的N结构域接触，但界面区域很小(约430埃(2))。我们认为酶底物结合在β桶的C末端的正电荷表面积上。然后，携带铁硫簇的C结构域可以移动以形成封闭的构象，其中底物被夹在N结构域和C结构域之间。本文完成了一组非甲氧戊酸途径酶的三维结构，这些酶是抗结核和抗疟疾药物的潜在靶点。(C)2010年由爱思唯尔有限公司出版。
IspG protein serves as the penultimate enzyme of the recently discovered non-mevalonate pathway for the biosynthesis of the universal isoprenoid precursors, isopentenyl diphosphate and dimethylallyl diphosphate. The enzyme catalyzes the reductive ring opening of 2C-methyl-D-erythritol 2,4-cyclodiphosphate, which affords 1-hydroxy-2-methyl-2-(E)-butenyl 4-diphosphate. The protein was crystallized under anaerobic conditions, and its three-dimensional structure was determined to a resolution of 2.7 angstrom. Each subunit of the c(2) symmetric homodimer folds into two domains connected by a short linker sequence. The N-terminal domain (N domain) is an eight-stranded beta barrel that belongs to the large TIM-barrel superfamily. The C-terminal domain (C domain) consists of a beta sheet that is flanked on both sides by helices. One glutamate and three cysteine residues of the C domain coordinate a [4Fe-4S] cluster. Homodimer formation involves an extended contact area (about 1100 angstrom(2)) between helices 8 and 9 of each respective beta barrel. Moreover, each C domain contacts the N domain of the partner subunit, but the interface regions are small (about 430 angstrom(2)). We propose that the enzyme substrate binds to the positively charged surface area at the C-terminal pole of the beta barrel. The C domain carrying the iron sulfur cluster could then move over to form a closed conformation where the substrate is sandwiched between the N domain and the C domain. This article completes the set of three-dimensional structures of the non-mevalonate pathway enzymes, which are of specific interest as potential targets for tuberculostatic and antimalarial drugs. (C) 2010 Published by Elsevier Ltd.