TOR complex 1 regulates the yeast plasma membrane proton pump and pH and potassium homeostasis

[EN] We have identified in yeast a connection between two master regulators of cell growth: a biochemical connection involving the TORC1 protein kinase (which activates protein synthesis, nutrient uptake, and anabolism) and a biophysical connection involving the plasma membrane proton-pumping H+ -ATPase Pma1 (which drives nutrient and K+ uptake and regulates pH homeostasis). Raising the temperature to nonpermissive values in a TOR thermosensitive mutant decreases Pma1 activity. Rapamycin, a TORC1 inhibitor, inhibits Pma1 dependent on its receptor Fpr1 and on the protein phosphatase Sit4, a TORC1 effector. Mutation of either Sit4 or Tco89, a nonessential subunit of TORC1, decreases proton efflux, K+ uptake, intracellular pH, cell growth, and tolerance to weak organic acids. Tco89 does not affect Pma1 activity but activates K+ transport.We thank Prof. Michael N. Hall (Basel) for strains SH100 and SH221, and Prof. Joaquin Arino (Barcelona) for strain BY4741 and its null mutant derivatives fpr1 Delta 0, sit4 Delta 0, and tco89 Delta 0. We also thank Prof. Francisco Portillo (Madrid) for the antibody against the double phosphorylation of Ser911 Thr912 in Pma1. This work was funded by grant PROME-TEOII/2014/041 from Generalitat Valenciana (Valencia, Spain).Mahmoud, S.; Planes Ferrer, MD.; Cabedo López, M.; Trujillo, C.; Rienzo, A.; Caballero Molada, M.; Sharma, SC.... (2017). TOR complex 1 regulates the yeast plasma membrane proton pump and pH and potassium homeostasis. FEBS Letters. 591(13):1993-2002. doi:10.1002/1873-3468.12673S199320025911