偶联钠离子转运草酰乙酸脱羧酶研究进展

摘要

偶联钠离子转运草酰乙酸脱羧酶是第一个被发现具有初级钠离子泵活性脱羧酶家族成员,由α,β,γ三个亚基以及生物素组成.由于其脱羧反应对柠檬酸发酵途径具有关键作用,并且在脱羧过程中偶联钠离子输出,该酶已受到学术界广泛关注.目前,该酶已在包括克雷伯菌属(Klebsiella)、沙门氏菌属(Salmonella)和弧菌属(Vibrio)等多个属细菌中被发现,并且其生理学基本特征已被鉴定.在肺炎克雷伯菌(Klebsiella pneumoniae)中,该酶中参与偶联脱羧反应钠离子输出重要氨基酸活性住点通过拓扑学分析、定点突变等方法被深入地进行鉴定,在此基础上能量偶联模型被提出以解释该酶偶联钠离子输出脱羧反应机制.本文对以上研究进展进行综述并对该酶未来研究方向加以展望.%Oxaloacetate decarboxylase is the first enzyme belonging to the Na+ transporting decarboxylase family demonstrated to act as a primary Na+ pump,which consists of α,β,y subunits with biotin as the prosthetic group.Due to the significant role of its decarboxylation reaction in citric acid fermentation pathway and Na+ translocation coupled to decarboxylation reaction from the cytoplasm into the periplasm,oxaloacetate decarboxylase has been widely studied.This enzyme has been found in such bacterial genera as Klebsiella,Vibrio and Salmonella and its basic physiological characteristics been detailedly identified.In Klebsiella pneumoniae,functionally important amino acid residues of oxaloacetate decarboxylase involved in Na+ transIocation coupled to decarboxylation reaction has been deeply chara-cterized through topological analysis,site-directed mutagenesis and etc,which is well explained by the following energy coupling molecular model presented recently.In this review,the above recent research progress is outlined and the further research focus is also prospected.