Characterization of the substrate binding domain in bacterial ADP-glucose pyrophosphorylase

ERBEN E; FIGUEROA C; FUSARI C; DEMONTE A; ALEANZI M; IGLESIAS AA; BALLICORA M; PREISS J

Bariloche

Congreso; XXXIX Reunión Anual de la SAIB y XXXII Reunión Anual de la SAB; 2003

SAIB

ADPGlcPPase is the key regulatory enzyme for the synthesis of glycogen and starch in bacteria and plants, respectively. The enzyme is allosterically regulated, with specificity for the regulator depending on the source. Accumulated evidence strongly suggests that ADPGlcPPases have a common folding pattern despite different quaternary structure and specificity for activator. Domains for substrate binding have been proposed in the predicted secondary structure of the enzyme. To analyze the validity of the prediction we characterized different mutants of bacterial ADPGlcPPase randomly generated by the linker-scanning mutagenesis. Results reinforce the structure model and agree with domains proposed for binding of ATP and Glc1P. Data also suggest the occurrence of conformational changes in the enzyme upon binding of the activator. The latter was further analyzed by characterization of site-directed mutants. It is suggested the occurrence of distinctive changes induced by ADPGlcPPase specific activators.