Structural evidence for induced fit and a mechanism for sugar/H+ symport in LacY
Structural evidence for induced fit and a mechanism for sugar/H+ symport in LacY
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DOI：
10.1038/sj.emboj.7601028
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发表时间：
2006-03-22
期刊：
影响因子：
11.4
通讯作者：
Kaback, HR
中科院分区：
文献类型：
--
作者：
Mirza, O;Guan, L;Kaback, HR
阳离子偶联主动转运是一个重要的细胞过程，在所有生物体中普遍存在。在这里，我们提出了两个新的配体的乳糖通透酶（LacY）的大肠杆菌在酸性和中性pH值下确定的X-射线结构，并提出了一个模型乳糖和H+易位之间的耦合机制。在不存在配体的情况下没有观察到糖结合位点，并且关键残基Glu（269）的去质子化与配体结合相关。因此，底物诱导糖结合位点的形成，以及H+转导的初始步骤。
Cation-coupled active transport is an essential cellular process found ubiquitously in all living organisms. Here, we present two novel ligand-free X-ray structures of the lactose permease (LacY) of Escherichia coli determined at acidic and neutral pH, and propose a model for the mechanism of coupling between lactose and H+ translocation. No sugar-binding site is observed in the absence of ligand, and deprotonation of the key residue Glu(269) is associated with ligand binding. Thus, substrate induces formation of the sugar-binding site, as well as the initial step in H+ transduction.