Glycogen metabolism in a Saccharomyces cerevisiae phosphoglucose isomerase (pgil) disruption mutant.
Disruption of the gene pgil of Saccharomyces cerevisiae, which codes for phosphoglucose isomerase, results in a dramatic increase in the amount of intracellular glycogen in early exponential cultures. The level of glucose 6-phosphate was much higher in mutant than in wild-type cells. Phosphorylase a activity and the state of activation of glycogen synthase were also investigated. Phosphorylase a activity was rather low along the culture in wild-type cells, whereas it was consistently higher in mutants. Glycogen synthase was mostly in the active form in early-medium exponential cultures in wild-type cells whereas the activation state of this enzyme in mutant cells, although lower at the earlier steps of the culture, did not differ from wild-type cells at later stages. The fact that the intracellular levels of UDP-glucose are markedly increased in mutant cells suggest that the observed accumulation of glycogen results from a rise in substrate availability rather than from the activation of the enzyme responsible for the synthesis of the polysaccharide.
Corominas
J
J
Departament de Bioquímica i Biologia Molecular, Facultat de Veterinària, Universitat Autònoma de Barcelona, Bellaterra, Spain.
Clotet
J
J
Fernández-Bañares
I
I
Boles
E
E
Zimmermann
F K
FK
Guinovart
J J
JJ
Ariño
J
J
D004789:Enzyme Activation; D005956:Glucose-6-Phosphate Isomerase / Q000235:genetics / Q000378:metabolism*; D005958:Glucosephosphates / Q000378:metabolism; D005964:Glucosyltransferases / Q000378:metabolism; D006003:Glycogen / Q000378:metabolism*; D006006:Glycogen Synthase / Q000378:metabolism; D009154:Mutation; D010762:Phosphorylase a / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology*
D005958:Glucosephosphates; D006003:Glycogen; D005964:Glucosyltransferases; D010762:Phosphorylase a; D006006:Glycogen Synthase; C059055:N-acetylglucosaminyldiphosphoundecaprenol glucosyltransferase; D005956:Glucose-6-Phosphate Isomerase