title: HasF, a TolC-homolog of Serratia marcescens, is involved in energy-dependent efflux.
abstract: A tolC-like gene (hasF) was identified upon scanning the incomplete database of the S. marcescens genome. This gene was amplified using PCR and cloned in the pUC18 vector to yield pUCHF. Sequencing of the S. marcescens tolC-like hasF gene and subsequent amino acid sequence prediction revealed approximately 80% amino acid homology with the Escherichia coli TolC. A tolC-deficient strain of E. coli (BL923) containing pUCHF/hasF was analyzed for susceptibility to fluoroquinolones (ciprofloxacin, norfloxacin, and ofloxacin), chloramphenicol, sodium dodecyl sulfate (SDS), and ethidium bromide. Antibiotic susceptibility assays of the E. coli tolC-deficient mutant BL923 demonstrated a 64-fold increase in resistance to SDS and ethidium bromide upon introduction of the S. marcescens tolC-like hasF gene. No change was observed for susceptibility to fluoroquinolones and chloramphenicol. Ethidium bromide accumulation assays performed using E. coli BL923:pUCHF established the role of the S. marcescens hasF gene product in proton gradient-dependent efflux.
authors.affiliation: Department of Microbiology, University of Manitoba, Winnipeg, MB R3T 2N2, Canada.
authors.forename: Ayush
authors.initials: A
authors.lastname: Kumar
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Worobec
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000502:physiology*; D004926:Escherichia coli / Q000187:drug effects / Q000378:metabolism; D004996:Ethidium / Q000032:analysis / Q000378:metabolism / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D017494:Proton Pumps / Q000378:metabolism*; D012706:Serratia marcescens / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D001425:Bacterial Outer Membrane Proteins; C103984:HasF protein, bacteria; D017494:Proton Pumps; D004996:Ethidium