title: Effects of nigericin and monactin on cation permeability of Streptococcus faecalis and metabolic capacities of potassium-depleted cells.
abstract: At a concentration of 10(-6)m, nigericin and monactin inhibited growth of Streptococcus faecalis, and the inhibition was reversed by addition of excess K(+). In the presence of certain antibiotics, the cells exhibited increased permeability to certain cations; internal Rb(+) was rapidly lost by exchange with external H(+), K(+) Rb(+), and, more slowly, with Na(+) and Li(+). No effect was observed on the penetration of other small molecules. Cation exchanges induced by nigericin and monactin were metabolically passive and apparently did not involve the energy-dependent K(+) pump. When the cells were washed, the cytoplasmic membrane recovered its original impermeability to cations. By use of monactin, we prepared cells whose K(+) content had been completely replaced by other cations, and the metabolic characteristics of K(+)-depleted cells were studied. Cells containing only Na(+) glycolyzed almost as well as did normal ones and, under proper conditions, could accumulate amino acids and orthophosphate. These cells also incorporated (14)C-uracil into ribonucleic acid but incorporation of (14)C-leucine into protein was strictly dependent upon the addition of K(+). When K(+) or Rb(+) was added to sodium-loaded cells undergoing glycolysis, these ions were accumulated by stoichiometric exchange for Na(+). From concurrent measurements of the rate of glycolysis, it was calculated that one mole-pair of cations was exchanged for each mole of adenosine triphosphate produced.
mesh_terms: D000255:Adenosine Triphosphate / Q000032:analysis; D000900:Anti-Bacterial Agents / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000096:biosynthesis; D001692:Biological Transport / Q000187:drug effects; D002247:Carbon Isotopes; D002463:Cell Membrane Permeability / Q000187:drug effects*; D003470:Culture Media; D013293:Enterococcus faecalis / Q000187:drug effects* / Q000378:metabolism; D006019:Glycolysis; D007474:Ion Exchange; D007930:Leucine / Q000378:metabolism; D008094:Lithium / Q000378:metabolism; D010759:Phosphorus Isotopes; D011188:Potassium / Q000378:metabolism* / Q000494:pharmacology; D012329:RNA, Bacterial / Q000096:biosynthesis; D011868:Radioisotopes; D012413:Rubidium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D014498:Uracil / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002247:Carbon Isotopes; D003470:Culture Media; D010759:Phosphorus Isotopes; D012329:RNA, Bacterial; D011868:Radioisotopes; D014498:Uracil; D000255:Adenosine Triphosphate; D008094:Lithium; D012964:Sodium; D007930:Leucine; D012413:Rubidium; D011188:Potassium