Inhibition of the yeast V‐type ATPase by cytosolic ADP

FEBS Letters

Kettner, Carsten²  Bertl, Adam²  Obermeyer, Gerhard¹ 

[1]Institut für Pflanzenphysiologie, Universität Salzburg, Hellbrunnerstrasse 34, A-5020 Salzburg, Austria

[2]Botanisches Institut I, Universität Karlsruhe (TH), Kaiserstrasse 12, 76128 Karlsruhe, Germany

关键词: V-ATPase;    Vacuole;    Patch-clamp;    Creatine kinase;    Bafilomycin;    H+ pump;   

DOI  :  10.1016/S0014-5793(02)03886-3

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The activity of the vacuolar H⁺-ATPase has been characterized in isolated vacuoles of the yeast Saccharomyces cerevisiae by means of the patch-clamp technique. With cytosolic calcium at virtually zero (<10⁻⁹ M), Mg-ATP induced a transient, bafilomycin A₁-sensitive current corresponding to the flow of positive charges from the cytoplasmic surface to the vacuolar lumen. The Mg-ATP-dependent current reached its maximum amplitude (30±8 mA m⁻² with 5 mM Mg-ATP, n=34) within 15–20 s and declined slowly over a period of about 15–20 min even in the continuous presence of Mg-ATP. This decline of pumping activity was independent of the cytosolic KCl concentration, suggesting an inhibitory mechanism different from the high salt-induced dissociation of V₀ and V₁ reported for the V-ATPase of plants and fungi. Cytosolic ADP was found to modulate the pump activity since Mg-ATP-induced pump current was smaller if monitored in the presence of 5 mM ADP and addition of 5 mM ADP in the presence of 5 mM Mg-ATP reduced the pump current by more than 50%. Furthermore, reduction of the cytosolic ADP concentration by the ATP-regenerating system creatine phosphate/creatine kinase partially relieved the endogenous inhibition of the V-ATPase, confirming that interaction of cytosolic ADP with the V-ATPase is the reason for the transient nature of the pump current in yeast vacuoles.

【 授权许可】

Unknown