title: The PGM3 gene encodes the major phosphoribomutase in the yeast Saccharomyces cerevisiae.
abstract: The phosphoglucomutases (PGM) Pgm1, Pgm2, and Pgm3 of the yeast Saccharomyces cerevisiae were tested for their ability to interconvert ribose-1-phosphate and ribose-5-phosphate. The purified proteins were studied in vitro with regard to their kinetic properties on glucose-1-phosphate and ribose-1-phosphate. All tested enzymes were active on both substrates with Pgm1 exhibiting only residual activity on ribose-1-phosphate. The Pgm2 and Pgm3 proteins had almost equal kinetic properties on ribose-1-phosphate, but Pgm2 had a 2000 times higher preference for glucose-1-phosphate when compared to Pgm3. The in vivo function of the PGMs was characterized by monitoring ribose-1-phosphate kinetics following a perturbation of the purine nucleotide balance. Only mutants with a deletion of PGM3 hyper-accumulated ribose-1-phosphate. We conclude that Pgm3 functions as the major phosphoribomutase in vivo.
authors.affiliation: Laboratoire d'Ingénierie des Systèmes Biologiques & des Procédés, UMR CNRS 5504 & INRA 792, Université de Toulouse, 135 avenue de Rangueil, F-31077 Toulouse cedex 04, France. thomas.walther@insa-toulouse.fr
authors.forename: Thomas
authors.initials: T
authors.lastname: Walther
authors.forename: Audrey
authors.initials: A
authors.lastname: Baylac
authors.forename: Ceren
authors.initials: C
authors.lastname: Alkim
authors.forename: Amélie
authors.initials: A
authors.lastname: Vax
authors.forename: Hélène
authors.initials: H
authors.lastname: Cordier
authors.forename: Jean Marie
authors.initials: JM
authors.lastname: François
mesh_terms: D005958:Glucosephosphates / Q000378:metabolism; D010733:Phosphoglucomutase / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D005958:Glucosephosphates; D029701:Saccharomyces cerevisiae Proteins; C031590:glucose-1-phosphate; D010733:Phosphoglucomutase