We report the first characterization of anl-arginine:glycine amidinotrans-ferase from a prokaryote. The enzyme, CyrA, is involved in the pathway for biosynthesis of the polyketide-derived hepatotoxin cylindrospermopsin from Cylindrospermopsis raciborskiiAWT205. CyrA is phylogenetically dis-tinct from other amidinotransferases, and structural alignment shows dif-ferences between the active site residues of CyrA and the well-characterized human l-arginine:glycine amidinotransferase (AGAT).
