CLONING AND CHARACTERIZATION OF A NOVEL MEMBRANE-ASSOCIATED LYMPHOCYTE NAD-ARGININE ADP-RIBOSYLTRANSFERASE

Mono-ADP-ribosylation is a post-translational modification of proteins in which the ADP-ribose moiety of NAD is transferred to proteins and is responsible for the toxicity of some bacterial toxins (e.g. cholera toxin and pertussis toxin). NAD:arginine ADP-ribosyltransferases clon ed from human and rabbit skeletal muscle and from mouse lymphoma (Yac- 1) cells are glycosylphosphatidylinositol-anchored and have similar en zymatic and physical properties; transferases cloned from chicken hete rophils and red cells have signal peptides and may be secreted. We rep ort here the cloning and characterization of an ADP-ribosyltransferase (Yac-2), also from Yac-1 lymphoma cells, that differs in properties f rom the previously identified eukaryotic transferases. The nucleotide and deduced amino acid sequences of the Yac-1 and Yac-2 transferases a re 58 and 33% identical, respectively. The Yac-2 protein is membrane-b ound but, unlike the Yac-1 enzyme, appears not to be glycosylphosphati dylinositol-anchored. The Yac-1 and Yac-2 enzymes, expressed as glutat hione S-transferase fusion proteins in Escherichia coli, were used to compare their ADP-ribosyltransferase and NAD glycohydrolase activities . Using agmatine as the ADP-ribose acceptor, the Yac-1 enzyme was pred ominantly an ADP-ribosyltransferase, whereas the transferase and NAD g lycohydrolase activities of the recombinant Yac-a protein were equival ent. The deduced amino acid sequence of the Yac-2 transferase containe d consensus regions common to several bacterial toxin and mammalian tr ansferases and NAD glycohydrolases, consistent with the hypothesis tha t there is a common mechanism of NAD binding and catalysis among ADP-r ibosyltransferases.