期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2010
卷号：107
期号：24
页码：11038-11043
DOI：10.1073/pnas.1003908107
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Resistance nodulation cell division (RND)-based efflux complexes mediate multidrug and heavy-metal resistance in many Gram-negative bacteria. Efflux of toxic compounds is driven by membrane proton/substrate antiporters (RND protein) in the plasma membrane, linked by a membrane fusion protein (MFP) to an outer-membrane protein. The three-component complex forms an efflux system that spans the entire cell envelope. The MFP is required for the assembly of this complex and is proposed to play an important active role in substrate efflux. To better understand the role of MFPs in RND-driven efflux systems, we chose ZneB, the MFP component of the ZneCAB heavy-metal efflux system from Cupriavidus metallidurans CH34. ZneB is shown to be highly specific for Zn2+ alone. The crystal structure of ZneB to 2.8 A resolution defines the basis for metal ion binding in the coordination site at a flexible interface between the {beta}-barrel and membrane proximal domains. The conformational differences observed between the crystal structures of metal-bound and apo forms are monitored in solution by spectroscopy and chromatography. The structural rearrangements between the two states suggest an active role in substrate efflux through metal binding and release.
