Arginine repressor (ArgR) is a prokaryotic repressor which regulates the arginine deiminase pathway. In this pathway, arginine is metabolized to form ammonia, CO2 and ATP. The ArgR releases the expression of the arginine deiminase pathway in the presence of arginine. The genes controlled by ArgR are not found in a single operon. While repressors are usually active as dimers, ArgR is a hexamer and binds to 2 palindromic DNA sites. The structure of ArgR shows a DNA-binding domain at the N-terminal and a C-terminal domain which contains the intersubunit interaction sites and the Arg binding site.
