title: A K+ yptake protein, TrkA, is required for serum, protamine, and polymyxin B resistance in Vibrio vulnificus.
abstract: Vibrio vulnificus, a highly virulent marine bacterium, is the causative agent of both serious wound infections and fatal septicemia in many areas of the world. To identify the genes required for resistance to human serum, we constructed a library of transposon mutants of V. vulnificus and screened them for hypersensitivity to human serum. Here we report that one of the isolated serum-susceptible mutants had a mutation in an open reading frame identified as trkA, a gene encoding an amino acid sequence showing high identity to that of TrkA of Vibrio alginolyticus, a protein required for the uptake of potassium. A trkA isogenic mutant was constructed via insertional inactivation, and it was significantly more easily killed by human serum, protamine, or polymyxin B than was the wild type. At K+ concentrations of 1 to 20 mM, this isogenic mutant showed attenuated growth compared to the wild-type strain. In addition, infection experiments demonstrated virulence attenuation when this mutant was administered intraperitoneally or subcutaneously to both normal and iron-treated mice, indicating that TrkA may modulate the transport of potassium and resistance to host innate defenses and that it is important for virulence in mice.
authors.affiliation: Department of Food Science, National Chung-Hsing University, Taichung, Taiwan.
authors.forename: Yu-Chung
authors.initials: YC
authors.lastname: Chen
authors.forename: Yin-Ching
authors.initials: YC
authors.lastname: Chuang
authors.forename: Chun-Chin
authors.initials: CC
authors.lastname: Chang
authors.forename: Chii-Ling
authors.initials: CL
authors.lastname: Jeang
authors.forename: Ming-Chung
authors.initials: MC
authors.lastname: Chang
mesh_terms: D000818:Animals; D001483:Base Sequence; D001770:Blood Bactericidal Activity; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology*; D002874:Chromosome Mapping; D004251:DNA Transposable Elements; D024881:Drug Resistance, Bacterial; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D011112:Polymyxin B / Q000494:pharmacology*; D011188:Potassium / Q000494:pharmacology; D011479:Protamines / Q000494:pharmacology*; D011817:Rabbits; D020917:Receptor, trkA; D014158:Transcription, Genetic; D041261:Vibrio vulnificus / Q000187:drug effects* / Q000276:immunology; D014774:Virulence
chemical_list: D002352:Carrier Proteins; D004251:DNA Transposable Elements; D008565:Membrane Proteins; D011479:Protamines; D020917:Receptor, trkA; D011112:Polymyxin B; D011188:Potassium