title: Activation of H(+)-ATPase by glucose in Saccharomyces cerevisiae involves a membrane serine protease.
abstract: BACKGROUND
  Glucose induces H(+)-ATPase activation in Saccharomyces 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 the 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 a kDa of 35-40 and an isoelectric point between 8 and 9. Analysis of several knockout yeast strains led to the detection of Lpx1p as the serine protease responsible of tubulin proteolysis. When lpx1Δ 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.
  
  
  CONCLUSIONS
  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.
  
  
  CONCLUSIONS
  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 proposes an indirect way to pharmacologically regulate yeast H(+)-ATPase activity and open the question about mechanistic similarities with other higher eukaryotes.
authors.affiliation: Departamento de Biología Molecular, Universidad Nacional de Río Cuarto, Río Cuarto, Córdoba, Argentina. acampetelli@exa.unrc.edu.ar
authors.forename: Alexis Nazareno
authors.initials: AN
authors.lastname: Campetelli
authors.forename: Noelia Edith
authors.initials: NE
authors.lastname: Monesterolo
authors.forename: Gabriela
authors.initials: G
authors.lastname: Previtali
authors.forename: Verónica Silvina
authors.initials: VS
authors.lastname: Santander
authors.forename: Marina Rafaela
authors.initials: MR
authors.lastname: Amaiden
authors.forename: Carlos Angel
authors.initials: CA
authors.lastname: Arce
authors.forename: Javier
authors.initials: J
authors.lastname: Valdez-Taubas
authors.forename: César Horacio
authors.initials: CH
authors.lastname: Casale
mesh_terms: D000107:Acetylation / Q000187:drug effects; D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000201:enzymology / Q000235:genetics; D004789:Enzyme Activation / Q000187:drug effects; D005947:Glucose / Q000494:pharmacology*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism; D010741:Phospholipases A / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D057057:Serine Proteases / Q000235:genetics / Q000378:metabolism*; D014404:Tubulin / Q000235:genetics / Q000378:metabolism*
chemical_list: D008565:Membrane Proteins; D046912:Multiprotein Complexes; D029701:Saccharomyces cerevisiae Proteins; D014404:Tubulin; C529526:Lpx1 protein, S cerevisiae; D010741:Phospholipases A; D057057:Serine Proteases; D000251:Adenosine Triphosphatases; D005947:Glucose