skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Crystal structures of the CusA efflux pump suggest methionine-mediated metal transport

Abstract

Gram-negative bacteria, such as Escherichia coli, frequently use tripartite efflux complexes in the resistance-nodulation-cell division (RND) family to expel various toxic compounds from the cell. The efflux system CusCBA is responsible for extruding biocidal Cu(I) and Ag(I) ions. No previous 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 new structural information about the HME subfamily 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. 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 ionsmore » from the cytosol, using these methionine pairs or clusters to bind and export metal ions. These structures suggest a stepwise shuttle mechanism for transport between these sites.« less

Authors:
; ; ; ; ; ;  [1];  [2]
  1. (Cornell)
  2. (
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
USDOE
OSTI Identifier:
1002727
Resource Type:
Journal Article
Journal Name:
Nature
Additional Journal Information:
Journal Volume: 467; Journal Issue: 09, 2010
Country of Publication:
United States
Language:
ENGLISH
Subject:
36 MATERIALS SCIENCE; BACTERIA; CONFORMATIONAL CHANGES; CRYSTAL STRUCTURE; ESCHERICHIA COLI; EXPORTS; GENETICS; METHIONINE; TRANSPORT

Citation Formats

Long, Feng, Su, Chih-Chia, Zimmermann, Michael T., Boyken, Scott E., Rajashankar, Kanagalaghatta R., Jernigan, Robert L., Yu, Edward W., and Iowa State). Crystal structures of the CusA efflux pump suggest methionine-mediated metal transport. United States: N. p., 2010. Web. doi:10.1038/nature09395.
Long, Feng, Su, Chih-Chia, Zimmermann, Michael T., Boyken, Scott E., Rajashankar, Kanagalaghatta R., Jernigan, Robert L., Yu, Edward W., & Iowa State). Crystal structures of the CusA efflux pump suggest methionine-mediated metal transport. United States. doi:10.1038/nature09395.
Long, Feng, Su, Chih-Chia, Zimmermann, Michael T., Boyken, Scott E., Rajashankar, Kanagalaghatta R., Jernigan, Robert L., Yu, Edward W., and Iowa State). Thu . "Crystal structures of the CusA efflux pump suggest methionine-mediated metal transport". United States. doi:10.1038/nature09395.
@article{osti_1002727,
title = {Crystal structures of the CusA efflux pump suggest methionine-mediated metal transport},
author = {Long, Feng and Su, Chih-Chia and Zimmermann, Michael T. and Boyken, Scott E. and Rajashankar, Kanagalaghatta R. and Jernigan, Robert L. and Yu, Edward W. and Iowa State)},
abstractNote = {Gram-negative bacteria, such as Escherichia coli, frequently use tripartite efflux complexes in the resistance-nodulation-cell division (RND) family to expel various toxic compounds from the cell. The efflux system CusCBA is responsible for extruding biocidal Cu(I) and Ag(I) ions. No previous 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 new structural information about the HME subfamily 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. 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, using these methionine pairs or clusters to bind and export metal ions. These structures suggest a stepwise shuttle mechanism for transport between these sites.},
doi = {10.1038/nature09395},
journal = {Nature},
number = 09, 2010,
volume = 467,
place = {United States},
year = {2010},
month = {9}
}