AcrA is a highly asymmetric protein capable of spanning the periplasm
AcrA is a highly asymmetric protein capable of spanning the periplasm
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DOI：
10.1006/jmbi.1998.2313
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发表时间：
1999-01-08
影响因子：
5.6
通讯作者：
Nikaido, H
中科院分区：
文献类型：
--
作者：
Zgurskaya, HI;Nikaido, H
AcrA蛋白是大肠杆菌多药外排复合体AcrAB-TolC的组成部分。根据AcrA突变体的过敏性表型判断，AcrAB-TolC系统能产生非常广泛的抗生素、化疗药物、洗涤剂和染料。这种复合体穿过大肠杆菌的内膜和外膜，并催化药物直接外流到介质中。内膜转运蛋白AcrB和外膜通道TolC的协调运行被认为是由AcrA介导的。后者是一种位于周质间隙的脂蛋白，我们在这里证明了AcrA的一个脂质缺乏的衍生物具有功能活性，这一点通过AcrA突变体的过敏性表型的互补来证明。纯化的非脂形式和完整形式的AcrA能够以相似的效率恢复钙蔗糖处理的大肠杆菌细胞中依赖AcrA的红霉素外排的活性。用分析超速离心法和动态光散射技术测定了非脂化AcrA的流体力学性质，发现AcrA以高度不对称的单体分子形式存在于溶液中，轴向比为8。这种拉长的形状与这种蛋白质跨越周质空间协调复合体的内外膜成分的协同操作的假说是一致的。(C)1999年学术出版社。
AcrA protein is a component of the multi-drug efflux complex AcrAB-TolC of Escherichia coli. Judged by the hypersusceptibility phenotype of acrA mutants, the AcrAB-TolC system pumps out an extraordinarily wide variety of antibiotics, chemotherapeutic agents, detergents and dyes. This complex traverses both the inner and outer membranes of E. coli and catalyzes efflux of the drugs directly into the medium. The coordinated operation of the inner membrane transporter AcrB and outer membrane channel TolC is thought to be mediated by AcrA. The latter is a lipoprotein located in the periplasmic space We show here that a lipid-deficient derivative of AcrA is functionally active as demonstrated by the complementation of the hypersusceptibility phenotype of the acrA mutant. Purified non-lipidated and intact forms of AcrA were able to restore, with similar efficiency, the activity of AcrA-dependent efflux of erythromycin in Ca2+-sucrose-treated E. coli cells. Using analytical ultracentrifugation and dynamic light scattering techniques we determined hydrodynamic properties of the non-lipidated AcrA and found that AcrA exists in solution as a highly asymmetric monomeric molecule with an axial ratio of 8. This elongated shape of AcrA is compatible with the hypothesis that this protein spans the periplasmic space coordinating the concerted operation of inner and outer membrane components of the complex. (C) 1999 Academic Press.