Menaquinone Biosynthesis: Biochemical and Structural Studies of Chorismate Dehydratase
Menaquinone Biosynthesis: Biochemical and Structural Studies of Chorismate Dehydratase
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DOI：
10.1021/acs.biochem.9b00105
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发表时间：
2019-04-09
期刊：
影响因子：
2.9
通讯作者：
Begley, Tadhg P.
中科院分区：
文献类型：
--
作者：
Mahanta, Nilkamal;Hicks, Katherine A.;Begley, Tadhg P.
孟喹酮(MK，维生素K)是一种脂溶性的苯醌，参与细菌的电子传递链。在哺乳动物细胞中，维生素K是一种必需的维生素，可以激活几种与血液凝结和骨骼代谢有关的蛋白质。MqnA是Futalosine依赖的合成孟喹酮途径上的第一个酶，通过失水催化分支酸的芳构化。在这里，我们报告了MqnA的生化和结构研究。这些研究表明，脱水反应是通过E1cb机制的变体进行的，在该机制中，去质子化比水分损失慢，底物的烯醇羧酸盐作为碱。
Menaquinone (MK, vitamin K) is a lipid-soluble quinone that participates in the bacterial electron transport chain. In mammalian cells, vitamin K functions as an essential vitamin for the activation of several proteins involved in blood clotting and bone metabolism. MqnA is the first enzyme on the futalosine-dependent pathway to menaquinone and catalyzes the aromatization of chorismate by water loss. Here we report biochemical and structural studies of MqnA. These studies suggest that the dehydration reaction proceeds by a variant of the E1cb mechanism in which deprotonation is slower than water loss and that the enol carboxylate of the substrate is serving as the base.