Campus Units
Biochemistry, Biophysics and Molecular Biology, Roy J. Carver Department of, Chemistry, Physics and Astronomy, Bioinformatics and Computational Biology, Molecular, Cellular and Developmental Biology
Document Type
Article
Publication Version
Accepted Manuscript
Publication Date
2010
Journal or Book Title
Nature
Volume
467
Issue
7314
First Page
484
Last Page
488
DOI
10.1038/nature09395
Abstract
Gram-negative bacteria, such as Escherichia coli, frequently utilize tripartite efflux complexes in the resistance-nodulation-cell division (RND) family to expel diverse toxic compounds from the cell.1,2 The efflux system CusCBA is responsible for extruding biocidal Cu(I) and Ag(I) ions.3,4 No prior structural information was available for the heavy-metal efflux (HME) subfamily of the RND efflux pumps. Here we describe the crystal structures of the inner membrane transporter CusA in the absence and presence of bound Cu(I) or Ag(I). These CusA structures provide important new structural information about the HME sub-family of RND efflux pumps. The structures suggest that the metal binding sites, formed by a three-methionine cluster, are located within the cleft region of the periplasmic domain. Intriguingly, this cleft is closed in the apo-CusA form but open in the CusA-Cu(I) and CusA-Ag(I) structures, which directly suggests a plausible pathway for ion export. Binding of Cu(I) and Ag(I) triggers significant conformational changes in both the periplasmic and transmembrane domains. The crystal structure indicates that CusA has, in addition to the three-methionine metal binding site, four methionine pairs - three located in the transmembrane region and one in the periplasmic domain. Genetic analysis and transport assays suggest that CusA is capable of actively picking up metal ions from the cytosol, utilizing these methionine pairs/clusters to bind and export metal ions. These structures suggest a stepwise shuttle mechanism for transport between these sites.
Copyright Owner
Macmillan Publishers Limited
Copyright Date
2010
Language
en
File Format
application/pdf
Recommended Citation
Long, Feng; Su, Chih-Chia; Zimmermann, Michael T.; Boyken, Scott E.; Rajashankar, Kanagalaghatta R.; Jernigan, Robert L.; and Yu, Edward W., "Crystal structures of the CusA efflux pump suggest methionine-mediated metal transport" (2010). Biochemistry, Biophysics and Molecular Biology Publications. 154.
https://lib.dr.iastate.edu/bbmb_ag_pubs/154
Included in
Biological and Chemical Physics Commons, Cell and Developmental Biology Commons, Molecular Biology Commons
Comments
This is a manuscript of an article published as Long, Feng, Chih-Chia Su, Michael T. Zimmermann, Scott E. Boyken, Kanagalaghatta R. Rajashankar, Robert L. Jernigan, and Edward W. Yu. "Crystal structures of the CusA efflux pump suggest methionine-mediated metal transport." Nature 467, no. 7314 (2010): 484. doi: 10.1038/nature09395. Posted with permission.