An allosteric trigger in the regulation of ADP-glucose Pyrophosphorylase from Actinobacteria

ASENCION DIEZ, MD; IGLESIAS, AA; CEREIJO, AE

Cordoba

Congreso; LII SAIB Annual meeting; 2016

SOCIEDAD ARGENTINA DE INVESTIGACIONES BIOQUIMICAS

ADP-glucose pyrophosphorylase (EC 2.7.7.27, ADPGlcPPase)is an allosteric enzyme regulated by metabolites from the main carbon route inthe organism. Previously, a motive present in all ADPGlcPPase containing Q andW specific residues was proposed as an allosteric trigger. We found that the ADPGlcPPasefrom actinobacteria is regulated by a plethora of effectors, although little isknown regarding the molecular aspects regarding the allosterism in this enzyme.Thus, we produced mutants in the allosteric triggers from the Streptomyces coelicolor (Q62A and W99A)and Rhodococcus jostii (Q61A andW98A) ADPGlcPPases. As an example, the Q62A mutant lost 12- and 19-foldactivation for PEP and fructose-6P respectively, compared to the wild typeenzyme. Importantly, this mutant has 23-fold less activation for glucose-6P,the main activator in the actinobacterial ADPGlcPPase. As well, the W99A mutantdecreased 28-fold its activation with for glucose-6P, compared to the wild typeenzyme and behaved similarly to the Q62A mutant regarding PEP and fructose-6Pactivation. Results confirm the importance of the allosteric trigger in theregulation of this enzyme and could be helpful to elucidate a regulatory/allostericmodel for the multi-regulated actinobacterial ADPGlcPPase.