title: NhaP1 is a K+(Na+)/H+ antiporter required for growth and internal pH homeostasis of Vibrio cholerae at low extracellular pH.
abstract: Vibrio cholerae has adapted to a wide range of salinity, pH and osmotic conditions, enabling it to survive passage through the host and persist in the environment. Among the many proteins responsible for bacterial survival under these diverse conditions, we have identified Vc-NhaP1 as a K(+)(Na(+))/H(+) antiporter essential for V. cholerae growth at low environmental pH. Deletion of the V. cholerae nhaP1 gene caused growth inhibition when external potassium was either limited (100 mM and below) or in excess (400 mM and above). This growth defect was most apparent at mid-exponential phase, after 4-6 h of culture. Using a pH-sensitive GFP, cytosolic pH was shown to be dependent on K(+) in acidic external conditions in a Vc-NhaP1-dependent manner. When functionally expressed in an antiporterless Escherichia coli strain and assayed in everted membrane vesicles, Vc-NhaP1 operated as an electroneutral alkali cation/proton antiporter, exchanging K(+) or Na(+) ions for H(+) within a broad pH range (7.25-9.0). These data establish the putative V. cholerae NhaP1 protein as a functional K(+)(Na(+))/H(+) antiporter of the CPA1 family that is required for bacterial pH homeostasis and growth in an acidic environment.
authors.affiliation: Department of Biomedical Sciences, College of Veterinary Sciences, Oregon State University, Corvallis, OR 97331, USA.|Department of Microbiology, Oregon State University, Corvallis, OR 97331, USA.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Quinn
authors.affiliation: Department of Microbiology, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada.
authors.forename: Craig T
authors.initials: CT
authors.lastname: Resch
authors.affiliation: Department of Microbiology, Oregon State University, Corvallis, OR 97331, USA.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Sun
authors.affiliation: Department of Biomedical Sciences, College of Veterinary Sciences, Oregon State University, Corvallis, OR 97331, USA.
authors.forename: Erin J
authors.initials: EJ
authors.lastname: Lind
authors.affiliation: Department of Microbiology, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada.
authors.forename: Pavel
authors.initials: P
authors.lastname: Dibrov
authors.affiliation: Department of Biomedical Sciences, College of Veterinary Sciences, Oregon State University, Corvallis, OR 97331, USA.|Department of Microbiology, Oregon State University, Corvallis, OR 97331, USA.
authors.forename: Claudia C
authors.initials: CC
authors.lastname: Häse
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D003593:Cytoplasm / Q000502:physiology; D017353:Gene Deletion; D006706:Homeostasis; D006863:Hydrogen-Ion Concentration; D011188:Potassium / Q000378:metabolism*; D027961:Potassium-Hydrogen Antiporters / Q000235:genetics / Q000378:metabolism*; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics / Q000378:metabolism*; D014734:Vibrio cholerae / Q000235:genetics / Q000254:growth & development* / Q000502:physiology
chemical_list: D001426:Bacterial Proteins; D027961:Potassium-Hydrogen Antiporters; D017923:Sodium-Hydrogen Exchangers; D011188:Potassium