Open AccessPresence of a sodium‐translocating ATPase in membrane vesicles of the homoacetogenic bacterium Acetobacterium woodii
Author(s) -
HEISE Reno,
MÜLLER Volker,
GOTTSCHALK Gerhard
Publication year - 1992
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1992.tb16959.x
Subject(s) - protonophore , valinomycin , chemistry , sodium , atpase , vesicle , atp hydrolysis , sodium azide , ionophore , atp synthase , membrane potential , biochemistry , membrane , enzyme , organic chemistry
Inverted membrane vesicles of the homoacetogenic bacterium Acetobacterium woodii catalyzed the hydrolysis of ATP with a rate of 100–150 nmol · min −1 · mg protein −1 . The ATPase was stimulated 1.4–1.6‐fold by NaCl and inhibited by N,N′ ‐dicyclohexylcarbodiimide, tributyltin or azide. The degree of inhibition caused by F 0 ‐directed but not F 1 ‐directed inhibitors was affected by the Na + concentration in the medium. These experiments indicated the presence of a sodium‐translocating ATPase. This was verified by transport studies. Upon addition of ATP to inverted vesicles, 22 Na + was actively transported into the intravesicular space up to a 24‐fold accumulation. Na + transport was inhibited by the sodium ionophore N,N,N′,N′, ‐tetracyclohexyl‐1,2‐phenyl‐enedioxydiacetamide but stimulated by valinomycin with potassium whereas the protonophore 3,5,‐di‐ tert ‐butyl‐4‐hydroxybenzylidenemalonitrile was without effect. N,N′ ‐dicyclohexylcarbodiimide and tributyltin inhibited 22 Na + transport. These experiments are in accordance with a primary electrogenic Na + transport as catalyzed by a F 1 F 0 ‐ATPase.