ADP-ribose-transfer enzymes catalyze the attachment of the ADP-ribose group of β-nicotinamide adenine dinucleotide (NAD+) to specific amino-acids (Arg, Cys, Asn, Thr) with simultaneous release of nicotinamide (nam). In eukaryotes ADP-ribosyltransferases (ARTs) are a family of enzyme composed of five members ART1-5. In prokaryotes mono-ADP-ribosylation is also a mechanism for bacterial pathogenesis, represented by a well characterized family of ADP-ribosylating toxins. NarE (Neisseria ADP-ribosylating enzyme) has been identified by a computational approach in the strain MC58 of the Gram-negative aerobic-anareobic facoltative N. meningitidis NarE, like other ADP-ribose-transfer enzymes, is able to ADP-ribosylate arginine and small guanidine compounds like agmatine and to hydrolase NAD in ADP-ribose and nicotinamide (nam) in the absence of the ADP-ribose acceptor. Toxins like ExoS from Pseudomonas aeruginosa, CT from Vibrio Cholerae and the mammalian ART2, ART5 exert the ability to recognize themselves as substrate, so we wonder whether NarE as well retains the ability to ADP-ribosylate itself.