Synechocystis sp. slr0787 protein is a novel bifunctional enzyme endowed with both nicotinamide mononucleotide adenylyltransferase and 'Nudix' hydrolase activities

Synechocystis sp. slr0787 open reading frame encodes a 339 residue polypept ide with a predicted molecular mass of 38.5 kDa. Its deduced amino acid seq uence shows extensive homology with known separate sequences of proteins fr om the thermophilic archaeon Methanococcus jannaschii. The N-terminal domai n is highly homologous to the archaeal NMN adenylyltransferase, which catal yzes NAD synthesis from NMN and ATP, The C-terminal domain shares homology with the archaeal ADP-ribose pyrophosphatase, a member of the 'Nudix' hydro lase family. The slr0787 gene has been cloned into a T7-based vector for ex pression in Escherichia coli cells. The recombinant protein has been purifi ed to homogeneity and demonstrated to possess both NMN adenylyltransferase and ADP-ribose pyrophosphatase activities. Both activities have been charac terized and compared to their archaeal counterparts. (C) 1999 Federation of European Biochemical Societies.