Structure and function of the GTP binding protein Gtr1 and its role in phosphate transport in Saccharomyces cerevisiae

• 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.

Ämnesord

NATURVETENSKAP  -- Kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences (hsv//eng)

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinsk bioteknologi -- Medicinsk bioteknologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Medical Biotechnology -- Medical Biotechnology (hsv//eng)

Nyckelord

Electron Spin Resonance Spectroscopy

Gene Deletion

Green Fluorescent Proteins/genetics/metabolism

Models

Molecular

Monomeric GTP-Binding Proteins/*chemistry/genetics/physiology

Phosphates/*metabolism

Protein Binding/genetics

Protein Conformation

Protein Transport/genetics

Proton-Phosphate Symporters/metabolism/physiology

Recombinant Fusion Proteins/metabolism

Saccharomyces cerevisiae

Proteins/*chemistry/genetics/metabolism/physiology

Structure-Activity Relationship

Thermodynamics

Biochemistry

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