Ornithine acetyltransferase (OAT) family; also referred to as ArgJ. OAT catalyzes the first and fifth steps in arginine biosynthesis, coupling acetylation of glutamate with deacetylation of N-acetylornithine, which allows recycling of the acetyl group in the arginine biosynthetic pathway. Members of this family may experience feedback inhibition by L-arginine. The active enzyme is a heterotetramer of two alpha and two beta chains, where the alpha and beta chains are the result of autocatalytic cleavage. OATs found in the clavulanic acid biosynthesis gene cluster catalyze the fifth step only, and may utilize acetyl acceptors other than glutamate.