Open AccessDiffering ability to transport nonmetal substrates by two RND‐type metal exporters
Author(s) -
Conroy Otakuye,
Kim EunHae,
McEvoy Megan M.,
Rensing Christopher
Publication year - 2010
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.2010.02006.x
Subject(s) - efflux , escherichia coli , context (archaeology) , substrate (aquarium) , metal , biology , multiprotein complex , biochemistry , chemistry , gene , organic chemistry , ecology , paleontology
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.