Sulfite and membrane energization induce two different active states of the Paracoccus denitrificans F0F1-ATPase.
Activation of the latent ATPase activity of inside-out vesicles from plasma membranes of Paracoccus denitrificans was studied. Several factors were found to induce activation: heat, membrane energization by succinate oxidation, methanol, oxyanions (sulfite, phosphate, arsenate, bicarbonate) and limited proteolysis with trypsin. Among the oxyanions, sulfite induced the higher increase in ATPase activity. Sulfite functioned as a nonessential activator that slightly modified the affinity for ATP and increased notoriously the Vmax. There was a competitive effect between sulfite, bicarbonate and phosphate for ATPase activation; their similar chemical geometry suggests that these oxyanions have a common binding site on the enzyme. Dithiothreitol did not affect the ATPase activity. ATPase activation by sulfite was decreased by uncoupler, enhanced by trypsin and inhibited by ADP, oligomycin and venturicidin. In contrast, activation induced by succinate was less sensitive to ADP, oligomycin, venturicidin and trypsin. It is proposed that the active states induced by sulfite and succinate reflect two conformations of the enzyme, in which the inhibitory subunit epsilon is differently exposed to trypsin.
Pacheco-Moisés
F
F
Departamento de Bioquímica, Instituto Nacional de Cardiología, México.
García
J J
JJ
Rodríguez-Zavala
J S
JS
Moreno-Sánchez
R
R
D000244:Adenosine Diphosphate / Q000378:metabolism / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000378:metabolism; D000838:Anions / Q000378:metabolism / Q000494:pharmacology; D001639:Bicarbonates / Q000378:metabolism / Q000494:pharmacology; D001665:Binding Sites; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D004734:Energy Metabolism / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis / Q000187:drug effects; D007700:Kinetics; D000432:Methanol / Q000378:metabolism / Q000494:pharmacology; D010231:Paracoccus denitrificans / Q000166:cytology / Q000201:enzymology*; D010710:Phosphates / Q000378:metabolism / Q000494:pharmacology; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D019802:Succinic Acid / Q000378:metabolism / Q000494:pharmacology; D013447:Sulfites / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000494:pharmacology*; D014357:Trypsin / Q000378:metabolism / Q000494:pharmacology; D014475:Uncoupling Agents / Q000378:metabolism / Q000494:pharmacology
D000838:Anions; D001639:Bicarbonates; D010710:Phosphates; D013447:Sulfites; D014475:Uncoupling Agents; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D019802:Succinic Acid; D014357:Trypsin; D006180:Proton-Translocating ATPases; D000432:Methanol