Energy-dependence of calcium accumulation during sporulation of Bacillus megaterium KM.
Ca2+ accumulation and endogenous respiration of sporulating Bacillus megaterium are inhibited to the same extent by electron-transport of inhibitors and the uncoupler carbonyl cyanide p-trifluoromethoxyphenylhydrazone, suggesting that Ca2+ is accumulated by an active transport process. Forespores isolated in stage V of sporulation demonstrated Ca2+-specific carrier-mediated Ca2+ uptake, consistent with downhill transfer [Hogarth & Ellar (1978) Biochem. J. 176, 197-203]. In the present studies forespore Ca2+ uptake was unaffected by carbonyl cyanide p-trifluoromethoxyphenylhydrazone and by concentrations of respiratory inhibitor that inhibited forespore endogenous respiration by 85%. These data suggest that Ca2+ enters the isolated forespore by facilitated diffusion. Ca2+ uptake into sporulating protoplasts was completely inhibited by concentrations of respiratory inhibitors that had no effect on either Ca2+ uptake or respiration of stage-V forespores, but which resulted in inhibition of mother-cell membrane NADH oxidase. These results indicate that the mother-cell membrane is a site for active transport of Ca2+ into the sporulating cell. The effects of the adenosine triphosphatase inhibitor dicyclohexylcarbodi-imide on mother-cell membrane adenosine triphosphatase, NADH oxidase and protoplast Ca2+ uptake were examined.
D001410:Bacillus megaterium / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D001693:Biological Transport, Active / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D004024:Dicyclohexylcarbodiimide / Q000494:pharmacology; D004734:Energy Metabolism / Q000187:drug effects*; D011523:Protoplasts / Q000187:drug effects / Q000378:metabolism; D013171:Spores, Bacterial / Q000187:drug effects / Q000378:metabolism; D014475:Uncoupling Agents / Q000494:pharmacology
D014475:Uncoupling Agents; D004024:Dicyclohexylcarbodiimide; D002118:Calcium