Mutagenesis of an amino acid residue in the activator-binding site of cyanobacterial ADP-glucose pyrophosphorylase causes alteration in activator specificity.
The specificity for activator of ADP-glucose pyrophosphorylase is closely related to the corresponding major carbon-assimilation pathway. The enzyme from Escherichia coli is mainly activated by fructose-1,6-P2, while the cyanobacterial, algal, and higher-plant enzymes are activated by 3-P-glycerate. Previous results have shown that Lys39 of the E. coli enzyme is involved in the binding of fructose-1,6-P2 while for the Anabaena enzyme, lysine residues 382 and 419 have been shown to be involved in the binding of 3-phosphoglycerate. This report shows that if Lys419 of the Anabaena enzyme is changed to glutamine, activation of the cyanobacterial enzyme by fructose-1,6-P2 becomes more effective than that of 3-P-glycerate at lower concentrations. Kinetic studies show that fructose-1,6-P2 competitively inhibits 3-P-glycerate activation of the Anabaena wild-type enzyme, suggesting that these two compounds bind to the same site. Thus a change of one amino acid at the activator binding domain can affect the specificity of activation of the Anabaena ADP-glucose pyrophosphorylase.
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Department of Biochemistry, Michigan State University, East Lansing 48824, USA.
Sheng
J
J
Preiss
J
J
D000494:Allosteric Regulation; D017033:Anabaena / Q000201:enzymology*; D001665:Binding Sites; D003001:Cloning, Molecular; D004926:Escherichia coli; D005635:Fructosediphosphates / Q000378:metabolism* / Q000494:pharmacology; D051599:Glucose-1-Phosphate Adenylyltransferase; D005994:Glycerophosphates / Q000378:metabolism / Q000494:pharmacology; D007700:Kinetics; D016297:Mutagenesis, Site-Directed; D009713:Nucleotidyltransferases / Q000378:metabolism*; D017354:Point Mutation; D011994:Recombinant Proteins / Q000378:metabolism; D013379:Substrate Specificity
D005635:Fructosediphosphates; D005994:Glycerophosphates; D011994:Recombinant Proteins; C029620:alpha-glycerophosphoric acid; D009713:Nucleotidyltransferases; D051599:Glucose-1-Phosphate Adenylyltransferase; C029063:fructose-1,6-diphosphate