ADP-glucose pyrophosphorylase from Gram positive bacteria

FIGUEROA CM; DEMONTE AM; ARIAS D; FERRONI F; GONZALEZ D; GUERRERO S; IGLESIAS AA; BALLICORA MA; PREISS J

Iguazú

Congreso; XL Reunión Anual de la SAIB; 2004

SAIB

Glycogen synthesis in bacteria takes place by the pathway utilizing ADP-Glc as the glucosyl donor, being the reaction catalyzed by the enzyme ADP-Glc pyrophosphorylase (ADP-Glc PPase) the regulatory step. ADP-Glc PPase from Gram negative bacteria has been extensively studied, mainly from Escherichia coli and Agrobacterium tumefaciens. In these, the enzyme was characterized as a homotetramer allosterically regulated by key metabolites of the main pathway for carbon utilization in the respective organism. Conversely, studies on ADP-Glc PPases from Gram positive bacteria are scarce. Between the latter, and after analysis of genome projects, two types could be distinguished: those from the firmicutes (low G+C) group that contain two different genes (glgC and glgD) coding for ADP-Glc PPase; and those from the high G+C group having only the glgC gene, as occurs in all other bacteria. We performed the molecular cloning of the genes coding for ADP-Glc PPase from different Gram positive bacteria: Mycobacterium tuberculosis and Streptomyces coelicolor (high G+C); and from Streptococcus mutans (low G+C). The respective genes were expressed and the recombinant proteins purified and characterized. Results show that the ADP-Glc PPases with the different structures exhibit dissimilar regulatory properties that could be associated with the distinctive metabolic pathways occurring in each microbial organism.