title: Structure and function of the GTP binding protein Gtr1 and its role in phosphate transport in Saccharomyces cerevisiae.
abstract: The Pho84 high-affinity phosphate permease is the primary phosphate transporter in the yeast Saccharomyces cerevisiae under phosphate-limiting conditions. The soluble G protein, Gtr1, has previously been suggested to be involved in the derepressible Pho84 phosphate uptake function. This idea was based on a displayed deletion phenotype of Deltagtr1 similar to the Deltapho84 phenotype. As of yet, the mode of interaction has not been described. The consequences of a deletion of gtr1 on in vivo Pho84 expression, trafficking and activity, and extracellular phosphatase activity were analyzed in strains synthesizing either Pho84-green fluorescent protein or Pho84-myc chimeras. The studies revealed a delayed response in Pho84-mediated phosphate uptake and extracellular phosphatase activity under phosphate-limiting conditions. EPR spectroscopic studies verified that the N-terminal G binding domain (residues 1-185) harbors the nucleotide responsive elements. In contrast, the spectra obtained for the C-terminal part (residues 186-310) displayed no evidence of conformational changes upon GTP addition.
authors.affiliation: Department of Biochemistry and Biophysics, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm, Sweden.
authors.forename: Jens O
authors.initials: JO
authors.lastname: Lagerstedt
authors.forename: Ian
authors.initials: I
authors.lastname: Reeve
authors.forename: John C
authors.initials: JC
authors.lastname: Voss
authors.forename: Bengt L
authors.initials: BL
authors.lastname: Persson
mesh_terms: D004578:Electron Spin Resonance Spectroscopy; D017353:Gene Deletion; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D020559:Monomeric GTP-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology; D010710:Phosphates / Q000378:metabolism*; D011485:Protein Binding / Q000235:genetics; D011487:Protein Conformation; D021381:Protein Transport / Q000235:genetics; D028081:Proton-Phosphate Symporters / Q000378:metabolism / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D013329:Structure-Activity Relationship; D013816:Thermodynamics
chemical_list: C121262:Gtr1 protein, S cerevisiae; C105495:PHO84 protein, S cerevisiae; D010710:Phosphates; D028081:Proton-Phosphate Symporters; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D049452:Green Fluorescent Proteins; D020559:Monomeric GTP-Binding Proteins