Characterization of the Substrate Binding Domain in Bacterial ADP-glucose Pyrophosphorylase

E. ERBEN, C. FIGUEROA, C. FUSARI, A. DEMONTE, M. ALEANZI, A.A. IGLESIAS, M.A. BALLICORA, J. PREISS

Bariloche, Río Negro, Argentina

Congreso; XXXIX Reunión Anual de SAIB; 2003

SAIB

BE-C14.CHARACTERIZATION OF THE SUBSTRATE BINDINGDOMAIN IN BACTERIAL ADP-GLUCOSEPYROPHOSPHORYLASEErben, Esteban; Figueroa, Carlos; Fusari, Corina; Demonte, Ana;Aleanzi, Mabel; Iglesias, Alberto A.Grupo Enzimología Molecular, BBM, Fac. Bioq. Cs. Biol.,UNLitoral. Paraje El Pozo, Santa Fe, 3000. Argentina. E-mail :iglesias@fbcb.unl.edu.arBallicora, Miguel; Preiss, Jack. Dept. Biochemistry & Mol. Biol.,Michigan State University, East Lanzing, MI, USA.ADPGlcPPase is the key regulatory enzyme for the synthesis ofglycogen and starch in bacteria and plants, respectively. Theenzyme is allosterically regulated, with specificity for the regulatordepending on the source. Accumulated evidence strongly suggeststhat ADPGlcPPases have a common folding pattern despitedifferent quaternary structure and specificity for activator. Domainsfor substrate binding have been proposed in the predicted secondarystructure of the enzyme. To analyze the validity of the predictionwe characterized different mutants of bacterial ADPGlcPPaserandomly generated by the linker-scanning mutagenesis. Resultsreinforce the structure model and agree with domains proposedfor binding of ATP and Glc1P. Data also suggest the occurrence ofconformational changes in the enzyme upon binding of theactivator. The latter was further analyzed by characterization ofsite-directed mutants. It is suggested the occurrence of distinctivechanges induced by ADPGlcPPase specific activators.Supported, in part ,by grants form ANPCyT (PICT?99 1-6074)and Fundación Antorchas.