title: Potassium transport of Salmonella is important for type III secretion and pathogenesis.
abstract: Intracellular cations are essential for the physiology of all living organisms including bacteria. Cations such as potassium ion (K(+)), sodium ion (Na(+)) and proton (H(+)) are involved in nearly all aspects of bacterial growth and survival. K(+) is the most abundant cation and its homeostasis in Escherichia coli and Salmonella is regulated by three major K(+) transporters: high affinity transporter Kdp and low affinity transporters Kup and Trk. Previous studies have demonstrated the roles of cations and cation transport in the physiology of Escherichia coli; their roles in the virulence and physiology of pathogenic bacteria are not well characterized. We have previously reported that the Salmonella K(+) transporter Trk is important for the secretion of effector proteins of the type III secretion system (TTSS) of Salmonella pathogenicity island 1 (SPI-1). Here we further explore the role of Salmonella cation transport in virulence in vitro and pathogenesis in animal models. Impairment of K(+) transport through deletion of K(+) transporters or exposure to the chemical modulators of cation transport, gramicidin and valinomycin, results in a severe defect in the TTSS of SPI-1, and this defect in the TTSS was not due to a failure to regulate intrabacterial pH or ATP. Our results also show that K(+) transporters are critical to the pathogenesis of Salmonella in mice and chicks and are involved in multiple growth and virulence characteristics in vitro, including protein secretion, motility and invasion of epithelial cells. These results suggest that cation transport of the pathogenic bacterium Salmonella, especially K(+) transport, contributes to its virulence in addition to previously characterized roles in maintaining homeostasis of bacteria.
authors.affiliation: Department of Bioscience and Technology, School of Life Science, Nanjing University, Nanjing, Jiangsu, PR China.|Program in Infectious Diseases and Immunity, School of Public Health, University of California, Berkeley, CA 94720, USA.
authors.forename: Yehao
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Program in Infectious Diseases and Immunity, School of Public Health, University of California, Berkeley, CA 94720, USA.
authors.forename: Katharina Kim
authors.initials: KK
authors.lastname: Ho
authors.affiliation: Department of Bioscience and Technology, School of Life Science, Nanjing University, Nanjing, Jiangsu, PR China.|Program in Infectious Diseases and Immunity, School of Public Health, University of California, Berkeley, CA 94720, USA.
authors.forename: Jing
authors.initials: J
authors.lastname: Su
authors.affiliation: Program in Infectious Diseases and Immunity, School of Public Health, University of California, Berkeley, CA 94720, USA.
authors.forename: Hao
authors.initials: H
authors.lastname: Gong
authors.affiliation: Program in Infectious Diseases and Immunity, School of Public Health, University of California, Berkeley, CA 94720, USA.
authors.forename: Alexander C
authors.initials: AC
authors.lastname: Chang
authors.affiliation: Program in Infectious Diseases and Immunity, School of Public Health, University of California, Berkeley, CA 94720, USA.
authors.forename: Sangwei
authors.initials: S
authors.lastname: Lu
mesh_terms: D000818:Animals; D058947:Bacterial Secretion Systems; D001692:Biological Transport; D002412:Cations / Q000378:metabolism; D002460:Cell Line; D002645:Chickens; D051379:Mice; D011188:Potassium / Q000378:metabolism*; D012475:Salmonella / Q000378:metabolism / Q000472:pathogenicity / Q000502:physiology*; D012481:Salmonella Infections, Animal / Q000382:microbiology / Q000473:pathology; D014774:Virulence
chemical_list: D058947:Bacterial Secretion Systems; D002412:Cations; D011188:Potassium