Abstract
In the genome of Synechocystis, there are five genes that encode a putative ADP-ribose pryophosphatase. Each of the recombinant proteins was overexpressed and their enzymatic activities were examined. Sll1054 and Slr0920 hydrolyzed ADP-ribose specifically, while Slr1134 hydrolyzed not only ADP-ribose but also NADH and FAD. By contrast, Slr1690 showed very low activity for ADP-ribose. Slr1690 had four substitutions of conserved amino acids. The replacement of the mutated amino acids with those conserved, increased hydrolytic activity, suggesting that Slr1690 might have been derived from an ADP-ribose pyrophosphatase. Clustering analysis suggested that the ADP-ribose pyrophosphatase family in Synechocystis appears to comprise a bacterial type and four phylogenetically diverse types that diversified via molecular evolution. The growth of insertional mutants, Δsll1054 and Δslr0920, was severely inhibited in the presence of 25 μ ADP-ribose, suggesting that Sll1054 and Slr0920 play a major role in the degradation of ADP-ribose.
