Negatively controls the expression of the four operons of arginine biosynthesis in addition to the carAB operon. Predominantly interacts with A/T residues in ARG boxes. It also binds to a specific site in cer locus. Thus it is essential for cer-mediated site-specific recombination in ColE1. It is necessary for monomerization of the plasmid ColE1. Amino-acid biosynthesis; L-arginine biosynthesis [regulation]. Homohexamer. Belongs to the ArgR family.