 Its molecular mass is 65.4 kDa, being composed of 587 amino acids.The recognition domain contains three subdomains (D1, D2 and D3) that are evolutionarily related to the DNA-binding domain of the catabolite gene activator protein which contains a helix-turn-helix.DNA cleavage is mediated through the non-specific cleavage domain which also includes the dimerisation surface.