<p>Many bacterial transcription regulation proteins bind DNA through a helix-turn-helix (HTH) motif, which can be classified into subfamilies on the basis of sequence similarities. The HTH GntR family has many members distributed among diverse bacterial groups that regulate various biological processes. It was named GntR after the <taxon tax_id="1423">Bacillus subtilis</taxon> repressor of the gluconate operon [<cite idref="PUB00001726"/>]. Family members include GntR, HutC, KorA, NtaR, FadR, ExuR, FarR, DgoR and PhnF. The crystal structure of the FadR protein has been determined [<cite idref="PUB00015228"/>]. In general, these proteins contain a DNA-binding HTH domain at the N terminus, and an effector-binding or oligomerisation domain at the C terminus (<db_xref db="INTERPRO" dbkey="IPR011711"/>). The DNA-binding domain is well conserved in structure for the whole of the GntR family, consisting of a 3-helical bundle core with a small beta-sheet (wing); the GntR winged helix structure is similar to that found in several other transcriptional regulator families. The regions outside the DNA-binding domain are more variable and are consequently used to define GntR subfamilies [<cite idref="PUB00015265"/>]. This entry represents the N-terminal DNA-binding domain of the GntR family.</p>