title: Potassium/proton antiport system of growing Enterococcus hirae at high pH.
abstract: The cytoplasmic pH (pHin) of Enterococcus hirae growing at pH 9.2 was maintained at about 8.1. Membrane-permeating amines such as ammonia alkalinized the pHin from 8.1 to 9.0 at a high concentration and induced K+ extrusion. The pHin alkalinization was transient; the pHin fell from 9.0 to the original value of pH 8.1, at which point K+ extrusion ceased, and remained constant. Cells accumulated ammonium ion to an extent stoichiometrically equivalent to the K+ loss. This bacterium continued to grow well under this condition. These results suggest that the pHin-responsive primary K+/H+ antiport system (Y. Kakinuma, and K. Igarashi, J. Biol. Chem. 263:14166-14170, 1988) works for the pHin regulation of this organism growing at a high pH.
authors.affiliation: Faculty of Pharmaceutical Sciences, Chiba University, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Kakinuma
authors.forename: K
authors.initials: K
authors.lastname: Igarashi
mesh_terms: D000588:Amines / Q000494:pharmacology; D017920:Antiporters / Q000378:metabolism*; D002455:Cell Division / Q000187:drug effects; D003593:Cytoplasm / Q000378:metabolism; D016983:Enterococcus / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D017136:Ion Transport / Q000187:drug effects; D011188:Potassium / Q000378:metabolism; D027961:Potassium-Hydrogen Antiporters; D011522:Protons; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology
chemical_list: D000588:Amines; D017920:Antiporters; D027961:Potassium-Hydrogen Antiporters; D011522:Protons; D000644:Quaternary Ammonium Compounds; D011188:Potassium