title: Members of the conserved DedA family are likely membrane transporters and are required for drug resistance in Escherichia coli.
abstract: Bacterial resistance to antibiotics and biocides is an increasing public health problem. Genes encoding integral membrane proteins belonging to the DedA family are present in most bacterial genomes, including Escherichia coli. An E. coli strain lacking partially redundant DedA family genes yqjA and yghB (strain BC202) displays temperature sensitivity and cell division defects. These phenotypes can be corrected by overexpression of mdfA, an Na(+)-K(+)/H(+) antiporter of the major facilitator superfamily. We show that BC202 is hypersensitive to several biocides and cationic compounds that are known substrates of several multidrug resistance transporters, including MdfA, EmrE, and AcrB. The introduction of deletions of genes encoding these drug transporters into BC202 results in additional sensitivity. Expression of wild-type yghB or yqjA can restore drug resistance, but this is eliminated upon mutation of two membrane-embedded acidic amino acids (E39 or D51 in either protein). This dependence upon membrane-embedded acidic amino acids is a hallmark of proton-dependent antiporters. Overexpression of mdfA in BC202 or artificially restoring proton motive force (PMF) restores wild-type resistance to substrates of MdfA as well as other drug resistance transporters such as EmrE and AcrAB. These results suggest that YqjA and YghB may be membrane transporters required for PMF-dependent drug efflux in E. coli.
authors.affiliation: Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, USA.
authors.forename: Sujeet
authors.initials: S
authors.lastname: Kumar
authors.forename: William T
authors.initials: WT
authors.lastname: Doerrler
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D017920:Antiporters / Q000235:genetics / Q000378:metabolism; D002455:Cell Division; D017124:Conserved Sequence; D024881:Drug Resistance, Bacterial / Q000187:drug effects / Q000235:genetics*; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D008074:Lipoproteins / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D018892:Proton-Motive Force / Q000187:drug effects / Q000235:genetics*; D016415:Sequence Alignment
chemical_list: D000900:Anti-Bacterial Agents; D017920:Antiporters; D029968:Escherichia coli Proteins; D008074:Lipoproteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D027425:ATP-Binding Cassette, Sub-Family C Proteins; C083497:AcrA protein, E coli; C083496:AcrB protein, E coli; C118438:Mdfa protein, E coli; C531000:YqjA protein, E coli; C075436:EmrE protein, E coli