The N-terminal domain of the V-ATPase subunit 'a' is regulated by pH in vitro and in vivo.
Regulation of the activity of vacuolar ATPase (V-ATPase) is a well known, yet poorly understood phenomenon, which might underlie the contribution of V-ATPases in various cellular signaling processes.(1) In yeast, V-ATPase is regulated by glucose and contributes to activation of cAMP-dependent protein kinase A (PKA). We have recently shown that, in vivo, glucose regulates V-ATPase through cytosolic pH, suggesting that V-ATPase contains a pH sensitive subunit, which regulates assembly of the holo-complex.(2) Here, we present the purification and biochemical characterization of the N-terminal domain of subunit 'a', Vph1N, which has been suggested to act as a pH sensor in mammalian cells.(3) Interestingly, our studies demonstrate pH-dependent oligomerization of this domain in vivo and in vitro. Moreover, we identify a membrane proximal region that is required for the pH-dependent oligomerization, and suggest a speculative model for the regulation of the V-ATPase holo-complex by pH.
Institute of Biochemistry, Department of Biology, ETH Zurich, Competence Center for Systems Physiology and Metabolic Diseases, Zurich, Switzerland. reinhard.dechant@bc.biol.ethz.ch
Reinhard
R
Dechant
Matthias
M
Peter
D003600:Cytosol / Q000201:enzymology; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary; D021122:Protein Subunits; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013329:Structure-Activity Relationship; D025262:Vacuolar Proton-Translocating ATPases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015003:Yeasts / Q000201:enzymology* / Q000235:genetics
D005656:Fungal Proteins; D021122:Protein Subunits; D011993:Recombinant Fusion Proteins; D025262:Vacuolar Proton-Translocating ATPases; D005947:Glucose