Differing ability to transport nonmetal substrates by two RND-type metal exporters

Otakuye Conroy-Ben, Eun Hae Kim, Megan M. McEvoy, Christopher Rensing

Research output: Contribution to journalArticlepeer-review

39 Scopus citations


The metal-exporting systems CusCFBA of Escherichia coli and GesABC of Salmonella are resistance-nodulation-division (RND)-type multiprotein systems responsible for detoxification during metal stress. In this study, the substrate range was determined for each metal transport system and possible amino acid residues important in substrate specificity were identified. The Ges system, previously identified as a gold-efflux system, conferred resistance to the greatest number and variety of organic chemicals including chloramphenicol, not recognized previously as a substrate. Phylogenetic analysis showed that GesB is most closely related to a class of RND transporters including MexF that have been shown to be responsible for exporting fluoroquinolones, chloramphenicol, and biocides. However, many of the closest homologs of GesABC appear to play a role in metal resistance judging from the genetic context. In contrast, CusCFBA belongs to a distinct family of RND-type monovalent metal-exporter systems containing a number of essential metal-binding methionines, resulting in a much narrower substrate range.

Original languageEnglish (US)
Pages (from-to)115-122
Number of pages8
JournalFEMS Microbiology Letters
Issue number2
StatePublished - Jul 2010


  • Copper efflux
  • Escherichia coli
  • Metal resistance
  • RND transporters

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology
  • Genetics


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