Enzymatic characteristics of two novel Myxococcus xanthus enzymes, PdeA and PdeB, displaying 3′,5′- and 2′,3′-cAMP phosphodiesterase, and phosphatase activities

Myxococcus xanthus PdeA and PdeB, enzymes homologous to class III 3′,5′-cyclic nucleotide phosphodiesterases, hydrolyzed 3′,5′- and 2′,3′-cyclic AMP (cAMP) to adenosine, and also demonstrated phosphatase activity toward nucleoside 5′-tri-, 5′-di-, 5′- and 3′-monophosphates with highest activities for nucleoside 5′-monophosphates. The substrate specificities of PdeA and PdeB show no similarity to that of any known cNMP phosphodiesterase, nucleotidase, or phosphatase. The enzyme activities of PdeA and PdeB were stimulated by 50 μM Mn²⁺ or Co²⁺. The K_m values of PdeA and PdeB for 3′,5′-cAMP, 2′,3′-cAMP, 5′-ATP, and 5′-AMP were in the low micromolar range (1.4-12.5  μM).