title: Sodium/proton antiport is required for growth of Escherichia coli at alkaline pH.
abstract: Evidence is presented indicating that Escherichia coli requires the Na+/H+ antiporter and external sodium (or lithium) ion to grow at high pH. Cells were grown in plastic tubes containing medium with a very low Na+ content (5-15 microM). Normal cells grew at pH 7 or 8 with or without added Na+, but at pH 8.5 external Na was required for growth. A mutant with low antiporter activity failed to grow at pH 8.5 with or without Na+. On the other hand, another mutant with elevated antiporter activity grew at a higher pH than normal (pH 9) in the presence of added Na+ or Li+. Amiloride, an inhibitor of the antiporter, prevented cells from growing at pH 8.5 (plus Na+), although it had no effect on growth in media of lower pH values.
authors.affiliation: Department of Cellular and Molecular Physiology, Harvard Medical School, Boston, MA 02115.
authors.forename: I
authors.initials: I
authors.lastname: McMorrow
authors.forename: H A
authors.initials: HA
authors.lastname: Shuman
authors.forename: D
authors.initials: D
authors.lastname: Sze
authors.forename: D M
authors.initials: DM
authors.lastname: Wilson
authors.forename: T H
authors.initials: TH
authors.lastname: Wilson
mesh_terms: D000584:Amiloride / Q000494:pharmacology; D002352:Carrier Proteins / Q000502:physiology*; D003470:Culture Media; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D006131:Growth Inhibitors / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D008094:Lithium / Q000494:pharmacology; D009154:Mutation; D012964:Sodium / Q000494:pharmacology; D017923:Sodium-Hydrogen Exchangers
chemical_list: D002352:Carrier Proteins; D003470:Culture Media; D006131:Growth Inhibitors; D017923:Sodium-Hydrogen Exchangers; D000584:Amiloride; D008094:Lithium; D012964:Sodium