Open AccessRegulation of Glutamine Synthetase from Saccharomyces cerevisiae by Repression, Inactivation and Proteolysis
Author(s) -
LEGRAIN Christiane,
VISSERS Stéphan,
DUBOIS Evelyne,
LEGRAIN Michèle,
WIAME JeanMarie
Publication year - 1982
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1982.tb06576.x
Subject(s) - glutamine synthetase , glutamine , saccharomyces cerevisiae , biochemistry , proteolysis , enzyme , yeast , biology , catabolism , psychological repression , amino acid , gene expression , gene
Glutamine synthetase activity is modulated by nitrogen repression and by two distinct inactivation processes. Addition of glutamine to exponentially grown yeast leads to enzyme inactivation. 50% of glutamine synthetase activity is lost after 30 min (a quarter of the generation time). Removing glutamine from the growth medium results in a rapid recovery of enzyme activity. A regulatory mutation ( gdhCR mutation) suppresses this inactivation by glutamine in addition to its derepressing effect on enzymes involved in nitrogen catabolism. The gdhCR mutation also increases the level of proteinase B in exponentially grown yeast. Inactivation of glutamine synthetase is also observed during nitrogen starvation. This inactivation is irreversible and consistes very probably of a proteolytic degradation. Indeed, strains bearing proteinase A, B and C mutations are no longer inactivated under nitrogen starvation.