Catalyzes two activities which are involved in the cyclic version of arginine biosynthesis: the synthesis of N-acetylglutamate from glutamate and acetyl-CoA as the acetyl donor, and of ornithine by transacetylation between N(2)-acetylornithine and glutamate. L-glutamate + N(2)-acetyl-L-ornithine = L-ornithine + N-acetyl-L-glutamate acetyl-CoA + L-glutamate = CoA + H(+) + N-acetyl-L-glutamate Amino-acid biosynthesis; L-arginine biosynthesis; L-ornithine and N-acetyl-L-glutamate from L-glutamate and N(2)-acetyl-L-ornithine (cyclic): step 1/1. Amino-acid biosynthesis; L-arginine biosynthesis; N(2)-acetyl-L-ornithine from L-glutamate: step 1/4. Heterotetramer of two alpha and two beta chains. Some bacteria possess a monofunctional ArgJ, i.e. capable of catalyzing only the fifth step of the arginine biosynthetic pathway. Belongs to the ArgJ family. Extended N-terminus.