Conserved Site

DNA-binding HTH domain, TetR-type, conserved site (IPR023772)

Short name: DNA-bd_HTH_TetR-type_CS


The TetR-type HTH domain is a DNA-binding, helix-turn-helix (HTH) domain of about 60 residues present in the TetR family of prokaryotic transcription regulators. Several of these bacterial regulators are repressors of genes and operons for membrane transport and cell envelope permeability. The family is named after the TetRacycline repressor TetR of enterobacteria found on Tn10 and other transposons and plasmids. The 'helix-turn-helix' DNA-binding motif is located in the N-terminal extremity of these transcriptional regulators [PMID: 8869638]. The C-terminal part of TetR-type regulators contains several regions that can be involved in (1) binding of inducers, which can be drugs, and (2) oligomerisation. The TetR and camR proteins are dimers, whilst qacR binds its operator as a pair of dimers and ethR seems to bind as an octamer [PMID: 10700280, PMID: 12456787]. TetR-type transcription regulators include several bacterial regulators of drug export systems that protect pathogenic bacteria against antibiotics, antiseptics, disinfectants and host-encoded antimicrobials [PMID: 12456787].

Several crystal structures of TetR-type transcription regulators have been resolved and their DNA-binding domains are formed by a three-helix bundle (H1-H3) and the N-terminal part of the following helix 4, which contributes to the hydrophobic centre of the DNA-binding domain and links it to the regulatory domain [PMID: 10700280]. The helix-turn-helix motif comprises the second and third helices, the third being called the recognition helix as it binds into the DNA major groove. The recognition helix of the TetR-type HTH is shorter than in most HTHs.

The signature pattern, of this entry, covers a conserved region that starts six residues before the HTH motif and ends seven residues after the HTH motif.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
PROSITE patterns