Publication Date:
2011-02-26
Description:
Gram-negative bacteria, such as Escherichia coli, expel toxic chemicals through tripartite efflux pumps that span both the inner and outer membrane. The three parts are an inner membrane, substrate-binding transporter; a membrane fusion protein; and an outer-membrane-anchored channel. The fusion protein connects the transporter to the channel within the periplasmic space. A crystallographic model of this tripartite efflux complex has been unavailable because co-crystallization of the various components of the system has proven to be extremely difficult. We previously described the crystal structures of both the inner membrane transporter CusA and the membrane fusion protein CusB of the CusCBA efflux system of E. coli. Here we report the co-crystal structure of the CusBA efflux complex, showing that the transporter (or pump) CusA, which is present as a trimer, interacts with six CusB protomers and that the periplasmic domain of CusA is involved in these interactions. The six CusB molecules seem to form a continuous channel. The affinity of the CusA and CusB interaction was found to be in the micromolar range. Finally, we have predicted a three-dimensional structure for the trimeric CusC outer membrane channel and developed a model of the tripartite efflux assemblage. This CusC(3)-CusB(6)-CusA(3) model shows a 750-kilodalton efflux complex that spans the entire bacterial cell envelope and exports Cu I and Ag I ions.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3078058/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉 〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3078058/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Su, Chih-Chia -- Long, Feng -- Zimmermann, Michael T -- Rajashankar, Kanagalaghatta R -- Jernigan, Robert L -- Yu, Edward W -- R01 GM072014/GM/NIGMS NIH HHS/ -- R01 GM074027/GM/NIGMS NIH HHS/ -- R01 GM074027-05/GM/NIGMS NIH HHS/ -- R01 GM086431/GM/NIGMS NIH HHS/ -- R01 GM086431-01A2/GM/NIGMS NIH HHS/ -- R01GM072014/GM/NIGMS NIH HHS/ -- R01GM074027/GM/NIGMS NIH HHS/ -- R01GM081680/GM/NIGMS NIH HHS/ -- R01GM086431/GM/NIGMS NIH HHS/ -- RR-15301/RR/NCRR NIH HHS/ -- England -- Nature. 2011 Feb 24;470(7335):558-62. doi: 10.1038/nature09743.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21350490" target="_blank"〉PubMed〈/a〉
Keywords:
Copper/metabolism
;
Crystallization
;
Crystallography, X-Ray
;
Escherichia coli/*chemistry
;
Escherichia coli Proteins/*chemistry/metabolism
;
Membrane Transport Proteins/*chemistry/metabolism
;
Metals, Heavy/*metabolism
;
Models, Molecular
;
Multiprotein Complexes/*chemistry/metabolism
;
Protein Binding
;
Protein Multimerization
;
Protein Structure, Quaternary
;
Protein Structure, Tertiary
;
Silver/metabolism
;
Static Electricity
Print ISSN:
0028-0836
Electronic ISSN:
1476-4687
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
,
Natural Sciences in General
,
Physics
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