Chimeric analysis of AcrA function reveals the importance of its c-terminal domain in its interaction with the AcrB multidrug efflux pump
Chimeric analysis of AcrA function reveals the importance of its c-terminal domain in its interaction with the AcrB multidrug efflux pump
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DOI：
10.1128/jb.185.18.5349-5356.2003
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发表时间：
2003-09-01
影响因子：
3.2
通讯作者：
Nikaido, H
中科院分区：
文献类型：
--
作者：
Elkins, CA;Nikaido, H
AcrAB-TolC是大肠杆菌中主要的组成型表达的外排蛋白复合物，其提供对多种抗菌剂的抗性。以前的研究表明，AcrA，膜融合蛋白家族的周质蛋白，可以与至少两个其他的阻力-增殖-分裂家族泵，AcrD和AcrF，除了其同源伴侣，AcrB。我们发现，除其他E。大肠杆菌耐药-增殖-分裂泵YhiV也能与AcrA共同发挥作用，而MdtB和MdtC则不能。当评估AcrB与AcrA同源物的功能时，只有AcrE，而不是YbiU或MdtA，可以补充AcrA缺乏。由于AcrA可以，但YhiU不能，与AcrB的功能，我们设计了一系列的嵌合突变体的这些蛋白质，以确定结构域的AcrA是必要的支持AcrB的功能。398个残基的蛋白质AcrA的290个残基的N-末端片段可以用编码YhiU的相应区域的序列替换，但是替换残基290和357之间的区域产生不能与AcrB一起起作用的蛋白质。相反，AcrA的357至397位残基的替换仍然产生功能蛋白。我们的结论是，一个小区域的AcrA接近，但不是在其C末端参与与其同源泵蛋白，AcrB的相互作用。
AcrAB-TolC is the major, constitutively expressed efflux protein complex that provides resistance to a variety of antimicrobial agents in Escherichia coli. Previous studies showed that AcrA, a periplasmic protein of the membrane fusion protein family, could function with at least two other resistance-nodulation-division family pumps, AcrD and AcrF, in addition to its cognate partner, AcrB. We found that, among other E. coli resistance-nodulation-division pumps, YhiV, but not MdtB or MdtC, could also function with AcrA. When AcrB was assessed for the capacity to function with AcrA homologs, only AcrE, but not YbiU or MdtA, could complement an AcrA deficiency. Since AcrA could, but YhiU could not, function with AcrB, we engineered a series of chimeric mutants of these proteins in order to determine the domain(s) of AcrA that is required for its support of AcrB function. The 290-residue N-terminal segment of the 398-residue protein AcrA could be replaced with a sequence coding for the corresponding region of YhiU, but replacement of the region between residues 290 and 357 produced a protein incapable of functioning with AcrB. In contrast, the replacement of residues 357 through 397 of AcrA still produced a functional protein. We conclude that a small region of AcrA close to, but not at, its C terminus is involved in the interaction with its cognate pump protein, AcrB.