The Escherichia coli NadR regulator is endowed with nicotinamide mononucleotide adenylyltransferase activity

The first identification and characterization of a catalytic activity assoc iated with NadR protein is reported. A computer-aided search for sequence s imilarity revealed the presence in NadR of a 29-residue region highly conse rved among known nicotinamide mononucleotide adenylyltransferases. The Esch erichia coli nadR gene was cloned into a T7-based vector and overexpressed. In addition to functionally specific DNA binding properties, the homogeneo us recombinant protein catalyzes NAD synthesis from nicotinamide mononucleo tide and ATP.