LPX1P SERIN PROTEASE PARTICIPATES IN THE GLUCOSE-INDUCED S. cerevisiae H+ -ATPASE ACTIVATION

CAMPETELLI AN; ORTIZ E; MONESTEROLO NE; AMAIDEN MR; PREVITALI G; VALDEZ-TAUBAS J; CASALE CH

Puerto Madryn

Congreso; 46 Annual Meeting Argentine Society for Biochemistry and Molecular Biology; 2010

In previous work we showed that acetylated tubulin interacts withsome P-ATPases inhibiting their enzymatic activities. In S.cerevisiae, the plasma membrane H+-ATPase is inhibited by tubulinand, upon glucose addition, the ATPase is activated and the tubulinis dissociated. Recently, we have shown that the tubulin dissociationis caused by degradation of the membrane tubulin by a serin likeprotease. In this work we show that the strain YOR084w, loosing aserin protease of 44 kDa and pI 8.4 is deficient in H+-ATPaseactivation and tubulin degradation when stimulated with glucose,indicating that this protease could be involved in the H+-ATPaseactivation mechanism. The complementation of the YOR084wstrain with the wild type form of the gene LPX1 showed that glucosecould activate the H+-ATPase activity through the degradation ofmembrane tubulin. These results demonstrate that glucose activatesthe plasma membrane H+-ATPase of S. cerevisiae in a mechanismwhich involves the hydrolysis of membrane tubulin by the action ofLpx1p which causes the dissociation of acetylated tubulin / H+-ATPase complex.