This probable domain is found in bacterial transcriptional regulators such as DeoR and SorC. One of these proteins, Q8U7I7, has an N-terminal helix-turn-helix IPR000792 that binds to DNA. This domain is probably the ligand regulator binding region. SorC is regulated by sorbose and other members of this family are likely to be regulated by other sugar substrates.
Rezacova P, Kozisek M, Moy SF, Sieglova I, Joachimiak A, Machius M, Otwinowski Z.
Crystal structures of the effector-binding domain of repressor Central glycolytic gene Regulator from Bacillus subtilis reveal ligand-induced structural changes upon binding of several glycolytic intermediates.
Mol. Microbiol. 69 2008 895-910
[PubMed: 18554327] http://dx.doi.org/10.1111/j.1365-2958.2008.06318.x