The Glycolytic Enzyme Aldolase Mediates Assembly, Expression, and Activity of Vacuolar H+-ATPase

Abstract

Vacuolar H+-ATPases (V-ATPases) are a family of highly conserved proton pumps that couple hydrolysis of cytosolic ATP to proton transport out of the cytosol. How ATP is supplied for V-ATPase-mediated hydrolysis and for coupling of proton transport is poorly understood. We have reported that the glycolytic enzyme aldolase physically associates with V-ATPase (Lu, M., Holliday, L. S., Zhang, L., Dunn, W. A., and Gluck, S. L. (2001) J. Biol. Chem. 276, 30407-30413). Here we show that aldolase interacts with three different subunits of V-ATPase (subunits a, B, and E). The binding sites for the V-ATPase subunits on aldolase appear to be on distinct interfaces of the glycolytic enzyme. Aldolase deletion mutant cells were able to grow in medium buffered at pH 5.5 but not at pH 7.5, displaying a growth phenotype similar to that observed in V-ATPase subunit deletion mutants. Abnormalities in V-ATPase assembly and protein expression observed in aldolase deletion mutant cells could be fully rescued by aldolase complementation. The interaction between aldolase and V-ATPase increased dramatically in the presence of glucose, suggesting that aldolase may act as a glucose sensor for V-ATPase regulation. Taken together, these findings provide functional evidence that the ATP-generating glycolytic pathway is directly coupled to the ATP-hydrolyzing proton pump through physical interaction between aldolase and V-ATPase.