title: The potassium transporter Trk and external potassium modulate Salmonella enterica protein secretion and virulence.
abstract: Potassium (K(+)) is the most abundant intracellular cation and is essential for many physiological functions of all living organisms; however, its role in the pathogenesis of human pathogens is not well understood. In this study, we characterized the functions of the bacterial Trk K(+) transport system and external K(+) in the pathogenesis of Salmonella enterica, a major food-borne bacterial pathogen. Here we report that Trk is important for Salmonella to invade and grow inside epithelial cells. It is also necessary for the full virulence of Salmonella in an animal infection model. Analysis of proteins of Salmonella indicated that Trk is involved in the expression and secretion of effector proteins of the type III secretion system (TTSS) encoded by Salmonella pathogenicity island 1 (SPI1) that were previously shown to be necessary for Salmonella invasion. In addition to the role of the Trk transporter in the pathogenesis of Salmonella, we discovered that external K(+) modulates the pathogenic properties of Salmonella by increasing the expression and secretion of effector proteins of the SPI1-encoded TTSS and by enhancing epithelial cell invasion. Our studies demonstrated that K(+) is actively involved in the pathogenesis of Salmonella and indicated that Salmonella may take advantage of the high K(+) content inside host cells and in the intestinal fluid during diarrhea to become more virulent.
authors.affiliation: Program in Infectious Diseases and Immunity, School of Public Health, University of California, Berkeley, California 94720-7354, USA.
authors.forename: Jing
authors.initials: J
authors.lastname: Su
authors.forename: Hao
authors.initials: H
authors.lastname: Gong
authors.forename: Jeff
authors.initials: J
authors.lastname: Lai
authors.forename: Andrew
authors.initials: A
authors.lastname: Main
authors.forename: Sangwei
authors.initials: S
authors.lastname: Lu
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism*; D004847:Epithelial Cells / Q000382:microbiology; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics / Q000502:physiology; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D009154:Mutation; D010538:Peritonitis / Q000382:microbiology; D011188:Potassium / Q000378:metabolism* / Q000494:pharmacology; D015221:Potassium Channels / Q000235:genetics* / Q000378:metabolism*; D012480:Salmonella Infections / Q000382:microbiology; D019779:Salmonella enterica / Q000187:drug effects / Q000378:metabolism* / Q000472:pathogenicity*; D012965:Sodium Chloride / Q000494:pharmacology; D013272:Stomach Diseases / Q000382:microbiology; D013997:Time Factors; D014774:Virulence
chemical_list: D001426:Bacterial Proteins; D015221:Potassium Channels; D012965:Sodium Chloride; D011188:Potassium