McHaourab Hassane S, Mishra Sanjay, Koteiche Hanane A, Amadi Sepan H
Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee 37232-0615, USA.
Biochemistry. 2008 Aug 5;47(31):7980-2. doi: 10.1021/bi800628d. Epub 2008 Jul 11.
EmrE is the prototype of small multidrug resistance transporters and has emerged as a model of membrane protein evolution. Analysis of the distances separating symmetry-related site-specific spin labels, correlation of topological sequence bias to C-terminal orientation, to membrane insertion efficiency, and to resistance to ethidium bromide collectively demonstrate that EmrE monomers adopt a parallel topology in the functional dimer. We propose a coupled insertion and assembly model for EmrE in which the favorable energetics of the parallel dimer interface override topological constraints arising from weak asymmetry in positive charge distribution.
EmrE是小多药耐药转运蛋白的原型，已成为膜蛋白进化的一个模型。对对称相关位点特异性自旋标记之间距离的分析、拓扑序列偏差与C端方向、膜插入效率以及对溴化乙锭抗性的相关性分析共同表明，EmrE单体在功能性二聚体中采用平行拓扑结构。我们提出了一种EmrE的耦合插入和组装模型，其中平行二聚体界面有利的能量克服了由正电荷分布的弱不对称性产生的拓扑限制。
