Chloride transport pathways and their bioenergetic implications in the obligate acidophile Bacillus coagulans
- 1 March 1990
- journal article
- research article
- Published by American Society for Microbiology in Journal of Bacteriology
- Vol. 172 (3) , 1485-1490
- https://doi.org/10.1128/jb.172.3.1485-1490.1990
Abstract
The protonophore-mediated collapse of the large delta pH that acidophiles maintain across their cytoplasmic membranes was augmented by the presence of Cl-, and Cl- influx into the cells occurred evidently in response to the protonophore-induced increase in the inside-positive membrane potential (+ delta psi). In respiring cells, the addition of Cl- but not SO4(2-) salts caused a rapid and precipitous decrease in the + delta psi. A Nernstian relationship between the imposed transmembrane K+ gradient and the valinomycin-induced K+ diffusion potentials was observed when everted membrane vesicles were loaded with K2SO4 or KH2PO4 but not when loaded with KCl or KNO3. Thus, electrogenic Cl- transport occurred in Bacillus coagulans. In addition, a nonelectrogenic temperature-sensitive Cl- transport mechanism, with the net Cl- efflux coefficient (PCl-) ranging from 1.5 x 10(-4) to 6.1 x 10(-6) cm/s, accounted for the massive Cl- efflux from Cl(-)-loaded cells. Thus, B. coagulans, despite its dependence on the + delta psi and therefore the need to exclude anions, apparently possesses specific mechanisms for Cl- permeation. Active cells of B. coagulans prevented Cl- accumulation from attaining an electrochemical equilibrium, maintaining a delta micro Cl- of ca. -63 mV. B. coagulans therefore also possesses an energy-dependent mechanism for Cl- exclusion from the cells.This publication has 36 references indexed in Scilit:
- RECENT ADVANCES IN BACTERIAL ION TRANSPORTAnnual Review of Microbiology, 1986
- An Apical-Membrane Chloride Channel in Human Tracheal EpitheliumScience, 1986
- The effect of general anesthetics on the proton and potassium permeabilities of liposomesBiochimica et Biophysica Acta (BBA) - Biomembranes, 1985
- Transport of protons and hydrochloric acid through lipid bilayer membranesBiochimica et Biophysica Acta (BBA) - Biomembranes, 1981
- Coupling between H+ entry and ATP formation in Escherichia coliBiochemical and Biophysical Research Communications, 1978
- Intracellular pH of Thermoplasma acidophilaBiochimica et Biophysica Acta (BBA) - Biomembranes, 1975
- Chloride flux in bilayer membranes. Electrically silent chloride flux in semispherical bilayersBiochemistry, 1975
- Widespread Occurrence of Acidophilic Strains of Bacillus coagulans in Hot SpringsJournal of Applied Bacteriology, 1974
- CHEMIOSMOTIC COUPLING IN OXIDATIVE AND PHOTOSYNTHETIC PHOSPHORYLATIONBiological Reviews, 1966
- Cation Transport in Escherichia coli The Journal of general physiology, 1962