This DNA binding domain is based on peptide fragmentation data. This domain is proximal to DNA in the promoter/holoenzyme complex. Furthermore this region contains a putative helix-turn-helix motif. At the C-terminus, there is a highly conserved region known as the RpoN box and is the signature of the sigma-54 proteins [1].

1: The bacterial enhancer-dependent sigma(54) (sigma(N)) transcription factor. Buck M, Gallegos MT, Studholme DJ, Guo Y, Gralla JD; J Bacteriol 2000;182:4129-4136. PMID:10894718