Protein kinases and phosphatases regulating the yeast proton pump

• Autores: Shima Mahmoud Ali Ibrahim Mahmoud Ali
• Directores de la Tesis: Ramón Serrano Salom (dir. tes.)
• Lectura: En la Universitat Politècnica de València ( España ) en 2015
• Idioma: inglés
• Tribunal Calificador de la Tesis: Francisco Portillo Pérez (presid.), José Miguel Mulet Salort (secret.), María Jesús Marcote (voc.)
• Materias:
  • Química
    • Bioquímica
      • Biología molecular
  • Ciencias de la vida
    • Microbiología
      • Micología (levaduras)
• Enlaces
  • Tesis en acceso abierto en: RiuNet
• Resumen

  • The plasma membrane H+-ATPase (Pma1) is essential for yeast growth and is activated by glucose metabolism by an unknown mechanism involving double phosphorylation of a regulatory site at the C-terminus (Ser911 Thr912). In this thesis we have investigated in Saccharomyces cerevisiae the role of two protein phosphatases, type 1 Glc7 and type 2A Sit4, and of an essential atypical protein kinase, TORC1, in the activation of Pma1 by glucose. The regulatory site of activated Pma1 can be dephosphorylated "in vitro" by recombinant Glc7 and Sit4, but inhibition "in vivo" of these phosphatases does not activate Pma1. Inhibition of Glc7 by regulated expression of a dominant-negative truncated form (the null mutant is not viable) had no effect on Pma1 activity while deletion of SIT4 gene decreased both Pma1 activity and double phosphorylation of the regulatory site. Inhibition of TORC1 protein kinase by treatment of yeast cells with the drug rapamycin or by exposure to non-permissive temperature of a temperature-sensitive mutant (tor1delta tor2ts) inhibited Pma1 and decreased double phosphorylation of the regulatory site. We conclude that Sit4 and TORC1 are required for full activation of Pma1 by glucose while Glc7 either does not participate or is redundant with other phosphatases.