title: Extrusion of sodium and hydrogen ions as the primary process in potassium ion accumulation by Streptococcus faecalis.
abstract: Glycolyzing cells of Streptococcus faecalis accumulate K(+) with concurrent extrusion of equivalent amounts of H(+) and Na(+). An attempt was made to clarify the retionship between the movements of Na(+) and K(+). Sodium was displaced from cells glycolyzing in the presence of ammonia, diethylamine, tris(hydroxymethyl)aminomethane, and other nitrogenous cations; by contrast, K(+) was completely retained. Accumulation of K(+) by heterologous exchange for Na(+) was not inhibited by antibiotics which facilitate diffusion of K(+) across the membrane, but was blocked by proton conductors. The results indicate that extrusion of Na(+) and H(+) from the cells is a primary, energy-linked process which generates an electrical potential (interior negative); K(+) accumulation occurs in response to this potential. Two mutants deficient in K(+) accumulation and retention were examined in terms of this model. One mutant is apparently defective in exchange of K(+) for H(+). In the other mutant, exchange of K(+) for Na(+) is impaired.
mesh_terms: D000588:Amines; D000596:Amino Acids; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001692:Biological Transport; D002463:Cell Membrane Permeability; D003470:Culture Media; D013293:Enterococcus faecalis / Q000254:growth & development / Q000378:metabolism*; D005827:Genetics, Microbial; D006019:Glycolysis; D006859:Hydrogen / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008697:Methane; D009154:Mutation; D011188:Potassium / Q000378:metabolism*; D011522:Protons; D000644:Quaternary Ammonium Compounds; D012964:Sodium / Q000378:metabolism*; D012975:Sodium Isotopes
chemical_list: D000588:Amines; D000596:Amino Acids; D000900:Anti-Bacterial Agents; D003470:Culture Media; D011522:Protons; D000644:Quaternary Ammonium Compounds; D012975:Sodium Isotopes; D006859:Hydrogen; D012964:Sodium; D008697:Methane; D011188:Potassium