Regulation of isocitrate dehydrogenase by phosphorylation in Escherichia coli K-12 and a simple method for determining the amount of inactive phosphoenzyme.
In several Escherichia coli K-12 strains grown on a limiting concentration of glucose, isocitrate dehydrogenase (IDH) was inactivated about 90% after cessation of growth upon exhaustion of the glucose. Such inactivation has been previously observed in several E. coli strains but not in E. coli K-12 (unless acetate was added to the bacterial culture when growth ceased). IDH was inactivated 75 to 80% in all E. coli K-12 strains we examined during growth on acetate. The inactivation involved phosphorylation of the enzyme and is considered to be a regulatory mechanism facilitating metabolite flow along the glyoxylate shunt. Phospho-IDH interacted with antibodies to enzymatically active IDH. We have devised a method, based on this immunological cross-reaction, for determining the proportions of active and inactive (phospho-) IDH in cell extracts.
Edlin
J D
JD
Department of Biochemistry and Applied Molecular Biology, University of Manchester Institute of Science and Technology, United Kingdom.
Sundaram
T K
TK
D000085:Acetates / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology* / Q000254:growth & development; D005947:Glucose / Q000378:metabolism; D007158:Immunologic Techniques; D007521:Isocitrate Dehydrogenase / Q000276:immunology / Q000378:metabolism*; D010750:Phosphoproteins / Q000276:immunology / Q000378:metabolism; D010766:Phosphorylation
D000085:Acetates; D010750:Phosphoproteins; D007521:Isocitrate Dehydrogenase; D005947:Glucose