Activation of H+-ATPase by glucose in Saccharomyces cerevisiae involves a membrane serine protease

CAMPETELLI AN; MONESTEROLO NE; PREVITALI G; SANTANDER VS; AMAIDEN M R; ARCE C A; VALDEZ-TAUBAS J; CASALE CH

BIOCHIMICA ET BIOPHYSICA ACTA-GENERAL SUBJECTS

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2013 p. 3593 - 3603

0304-4165

Background: Glucose induces H+-ATPase activation in S. cerevisiae. Our previous study showed that (i)S.cerevisiae plasma membrane H+-ATPase forms a complex with acetylated tubulin (AcTub), resulting in inhibition of the enzyme activity; (ii) exogenous glucose addition results in dissociation of the complex and recovery of the enzyme activity. Methods: We used classic biochemical and molecular biology tools in order to identify the key components in the mechanism that leads to H+-ATPase activation after glucose treatment. Results: We demonstrate that glucose-induced dissociation of the complex is due to pH-dependent activation of a protease that hydrolyzes membrane tubulin. Biochemical analysis identified a serine protease with kDa 35-40 and an isoelectric point between 8 and 9. Analysis of several knockout yeast strains led to the detection ofLpx1p as the serine protease responsible of tubulin proteolysis. When lpx1∆ cells were treated with glucose, tubulin was not degraded, the AcTub/H+-ATPase complex did not undergo dissociation, and H+-ATPase activation was significantly delayed. Conclusion: Our findings indicate that the mechanism of H+-ATPase activation by glucose involves a decrease in the cytosolic pH and consequent activation of a serine protease that hydrolyzes AcTub, accelerating the process of the AcTub/H+-ATPase complex dissociation and the activation of the enzyme. General significance: Our data sheds light into the mechanism by which acetylated tubulin dissociates from the yeast H+-ATPase, identifying a degradative step that remained unknown. This finding also propose an indirect way to pharmacologically regulate yeast H+-ATPase activity and open the question about mechanistic similarities with other higher eukaryotes.