This domain makes a direct interaction with the core RNA polymerase, to form an enhancer dependent holoenzyme [1]. The centre of this domain contains a very weak similarity to a helix-turn-helix motif which may represent the other DNA binding domain.

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