Ornithine carbamoyltransferase (OTC) catalyzes the reversible transfer of the carbamoyl group from carbamoyl phosphate (CP) to the Nε atom of L-ornithine (ORN) to produce L-citrulline. There are two types of the enzyme – anabolic (aOTC) and catabolic (cOTC). Anabolic OTCs participate in the urea cycle and L-arginine biosynthesis. Catabolic OTCs are part of the catabolic arginine deiminase pathway found in a number of microorganisms. The reported structure is for the anabolic enzyme from pathogen Vibrio vulnificus. The structure has three monomers in the asymmetric unit which form the physiologically active trimer. All three enzyme subunits are unliganded. This structure provides insights into native state of the enzyme featuring open interdomain cleft, disordered SMG loop and catalytic loop B2–H3 located out of the active site.