title: Role of the Na(+)-translocating NADH:quinone oxidoreductase in voltage generation and Na(+) extrusion in Vibrio cholerae.
abstract: For Vibrio cholerae, the coordinated import and export of Na(+) is crucial for adaptation to habitats with different osmolarities. We investigated the Na(+)-extruding branch of the sodium cycle in this human pathogen by in vivo (23)Na-NMR spectroscopy. The Na(+) extrusion activity of cells was monitored after adding glucose which stimulated respiration via the Na(+)-translocating NADH:quinone oxidoreductase (Na(+)-NQR). In a V. cholerae deletion mutant devoid of the Na(+)-NQR encoding genes (nqrA-F), rates of respiratory Na(+) extrusion were decreased by a factor of four, but the cytoplasmic Na(+) concentration was essentially unchanged. Furthermore, the mutant was impaired in formation of transmembrane voltage (ΔΨ, inside negative) and did not grow under hypoosmotic conditions at pH8.2 or above. This growth defect could be complemented by transformation with the plasmid encoded nqr operon. In an alkaline environment, Na(+)/H(+) antiporters acidify the cytoplasm at the expense of the transmembrane voltage. It is proposed that, at alkaline pH and limiting Na(+) concentrations, the Na(+)-NQR is crucial for generation of a transmembrane voltage to drive the import of H(+) by electrogenic Na(+)/H(+) antiporters. Our study provides the basis to understand the role of the Na(+)-NQR in pathogenicity of V. cholerae and other pathogens relying on this primary Na(+) pump for respiration.
authors.affiliation: Institute of Microbiology, University of Hohenheim (Stuttgart), Garbenstraße 30, 70599 Stuttgart, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Vorburger
authors.affiliation: Department of Chemistry, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany.
authors.forename: Ruslan
authors.initials: R
authors.lastname: Nedielkov
authors.affiliation: Department of Biology, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Brosig
authors.affiliation: Institute of Microbiology, University of Hohenheim (Stuttgart), Garbenstraße 30, 70599 Stuttgart, Germany.
authors.forename: Eva
authors.initials: E
authors.lastname: Bok
authors.affiliation: Institute of Microbiology, University of Hohenheim (Stuttgart), Garbenstraße 30, 70599 Stuttgart, Germany.
authors.forename: Emina
authors.initials: E
authors.lastname: Schunke
authors.affiliation: Institute of Microbiology, University of Hohenheim (Stuttgart), Garbenstraße 30, 70599 Stuttgart, Germany.
authors.forename: Wojtek
authors.initials: W
authors.lastname: Steffen
authors.affiliation: Interfaculty Institute of Microbiology and Infection Medicine, Department of Microbial Genetics, University of Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, Germany.
authors.forename: Sonja
authors.initials: S
authors.lastname: Mayer
authors.affiliation: Interfaculty Institute of Microbiology and Infection Medicine, Department of Microbial Genetics, University of Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, Germany.
authors.forename: Friedrich
authors.initials: F
authors.lastname: Götz
authors.affiliation: Department of Chemistry, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany. Electronic address: hmoeller@uni-potsdam.de.
authors.forename: Heiko M
authors.initials: HM
authors.lastname: Möller
authors.affiliation: Institute of Microbiology, University of Hohenheim (Stuttgart), Garbenstraße 30, 70599 Stuttgart, Germany. Electronic address: julia.steuber@uni-hohenheim.de.
authors.forename: Julia
authors.initials: J
authors.lastname: Steuber
mesh_terms: D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D008564:Membrane Potentials; D011808:Quinone Reductases / Q000502:physiology*; D012964:Sodium / Q000378:metabolism*; D014734:Vibrio cholerae / Q000378:metabolism*
chemical_list: D012964:Sodium; C041831:NADH dehydrogenase (quinone); D011808:Quinone Reductases
keywords: Hypoosmotic stress; Na(+) homeostasis; Nuclear magnetic resonance (NMR); Respiration; Sodium transport; Vibrio cholerae