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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
2010-2-12
pubmed:abstractText
RND (resistance-nodulation-division) family transporters in Gram-negative bacteria frequently pump out a wide range of inhibitors and often contribute to multidrug resistance to antibiotics and biocides. An archetypal RND pump of Escherichia coli, AcrB, is known to exist as a homotrimer, and this construction is essential for drug pumping through the functionally rotating mechanism. MdtBC, however, appears different because two pump genes coexist within a single operon, and genetic deletion data suggest that both pumps must be expressed in order for the drug efflux to occur. We have expressed the corresponding genes, with one of them in a His-tagged form. Copurification of MdtB and MdtC under these conditions showed that they form a complex, with an average stoichiometry of 2:1. Unequivocal evidence that only the trimer containing two B protomers and one C protomer is active was obtained by expressing all possible combinations of B and C in covalently linked forms. Finally, conversion into alanine of the residues, known to form a proton translocation pathway in AcrB, inactivated transport only when made in MdtB, not when made in MdtC, a result suggesting that MdtC plays a different role not directly involved in drug binding and extrusion.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
1098-5530
pubmed:author
pubmed:issnType
Electronic
pubmed:volume
192
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1377-86
pubmed:dateRevised
2010-9-2
pubmed:meshHeading
pubmed:year
2010
pubmed:articleTitle
Multidrug efflux pump MdtBC of Escherichia coli is active only as a B2C heterotrimer.
pubmed:affiliation
Department of Molecular and Cell Biology, 426 Barker Hall, University of California, Berkeley, CA 94720-3202, USA.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't