Proteins of newly isolated mutants and the amino-terminal proline are essential for ubiquitin-proteasome-catalyzed catabolite degradation of fructose-1,6-bisphosphatase of Saccharomyces cerevisiae.
Addition of glucose to cells of the yeast Saccharomyces cerevisiae growing on a non-fermentable carbon source leads to selective and rapid degradation of fructose-1,6-bisphosphatase. This so called catabolite inactivation of the enzyme is brought about by the ubiquitin-proteasome system. To identify additional components of the catabolite inactivation machinery, we isolated three mutant strains, gid1, gid2, and gid3, defective in glucose-induced degradation of fructose-1,6-bisphospha-tase. All mutant strains show in addition a defect in catabolite inactivation of three other gluconeogenic enzymes: cytosolic malate dehydrogenase, isocitrate lyase, and phosphoenolpyruvate carboxykinase. These findings indicate a common mechanism for the inactivation of all four enzymes. The mutants were also impaired in degradation of short-lived N-end rule substrates, which are degraded via the ubiquitin-proteasome system. Site-directed mutagenesis of the amino-terminal proline residue yielded fructose-1,6-bisphosphatase forms that were no longer degraded via the ubiquitin-proteasome pathway. All amino termini other than proline made fructose-1,6-bisphosphatase inaccessible to degradation. However, the exchange of the amino-terminal proline had no effect on the phosphorylation of the mutated enzyme. Our findings suggest an essential function of the amino-terminal proline residue for the degradation process of fructose-1,6-bisphosphatase. Phosphorylation of the enzyme was not necessary for degradation to occur.
Hämmerle
M
M
Institut für Biochemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany.
Bauer
J
J
Rose
M
M
Szallies
A
A
Thumm
M
M
Düsterhus
S
S
Mecke
D
D
Entian
K D
KD
Wolf
D H
DH
D000595:Amino Acid Sequence; D001483:Base Sequence; D001704:Biopolymers / Q000378:metabolism; D002384:Catalysis; D017931:DNA Primers; D016521:Electrophoresis, Gel, Pulsed-Field; D006597:Fructose-Bisphosphatase / Q000235:genetics / Q000378:metabolism*; D006868:Hydrolysis; D007522:Isocitrate Lyase / Q000037:antagonists & inhibitors; D007700:Kinetics; D008291:Malate Dehydrogenase / Q000037:antagonists & inhibitors; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010447:Peptide Hydrolases / Q000378:metabolism*; D019764:Phosphoenolpyruvate Carboxykinase (ATP) / Q000037:antagonists & inhibitors; D010766:Phosphorylation; D025821:Polyubiquitin; D011392:Proline / Q000235:genetics / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D013379:Substrate Specificity; D014452:Ubiquitins / Q000378:metabolism
D001704:Biopolymers; D017931:DNA Primers; D014452:Ubiquitins; D025821:Polyubiquitin; D011392:Proline; D008291:Malate Dehydrogenase; D006597:Fructose-Bisphosphatase; D010447:Peptide Hydrolases; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease; D019764:Phosphoenolpyruvate Carboxykinase (ATP); D007522:Isocitrate Lyase