title: The N-terminal region is important for the allosteric activation and inhibition of the Escherichia coli ADP-glucose pyrophosphorylase.
abstract: The ADPglucose pyrophosphorylase (EC 2.7.7.27) from Escherichia coli is allosterically activated by fructose 1,6-bisphosphate and inhibited by AMP. Proteolysis of the enzyme with proteinase K causes loss of activity and generates two peptides, 21 and 28 kDa, from the 49.7-kDa subunit. The presence of ADPglucose, Mg2+, and fructose 1, 6-bisphosphate during the incubation with proteinase K protected the enzyme activity and prevented cleavage at sites Met181-Ala182 and Phe192-Val193. Proteolysis of the protected enzyme removed 10 to 13 amino acids from the N-terminal and 2 amino acids from the C-terminal. The resulting enzyme was almost independent of the need for fructose 1,6-bisphosphate for maximal activity and insensitive to inhibition by AMP. The apparent affinity for the substrates was similar to that of the fully-activated wild-type enzyme. These data suggest that amino acid residues in the N-terminal portion and possibly the C-terminal portion of ADPglucose pyrophosphorylase are part of the regulatory domain of the enzyme, critical for allosteric regulation of the enzyme.
authors.affiliation: Department of Biochemistry, Michigan State University, East Lansing, Michigan, 48824, USA.
authors.forename: M X
authors.initials: MX
authors.lastname: Wu
authors.forename: J
authors.initials: J
authors.lastname: Preiss
mesh_terms: D000494:Allosteric Regulation; D000595:Amino Acid Sequence; D019286:Endopeptidase K / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D004926:Escherichia coli / Q000201:enzymology*; D051599:Glucose-1-Phosphate Adenylyltransferase; D006868:Hydrolysis; D007700:Kinetics; D008274:Magnesium / Q000378:metabolism; D008969:Molecular Sequence Data; D009713:Nucleotidyltransferases / Q000037:antagonists & inhibitors* / Q000302:isolation & purification / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism* / Q000502:physiology; D013379:Substrate Specificity
chemical_list: D010446:Peptide Fragments; D009713:Nucleotidyltransferases; D051599:Glucose-1-Phosphate Adenylyltransferase; D019286:Endopeptidase K; D008274:Magnesium