DNA binding HTH domain, AraC-type (IPR018060)

Short name: HTH_AraC

Overlapping homologous superfamilies


Domain relationships



Many bacterial transcription regulation proteins bind DNA through a 'helix-turn-helix' (HTH) motif. One major subfamily of these proteins [PMID: 8451183, PMID: 2314271] is related to the arabinose operon regulatory protein AraC [PMID: 8451183, PMID: 2314271. Except for celD [PMID: 2179047], all of these proteins seem to be positive transcriptional factors.

Although the sequences belonging to this family differ somewhat in length, in nearly every case the HTH motif is situated towards the C terminus in the third quarter of most of the sequences. The minimal DNA binding domain spans roughly 100 residues and comprises two HTH subdomains; the classical HTH domain and another HTH subdomain with similarity to the classical HTH domain but with an insertion of one residue in the turn-region. The N-terminal and central regions of these proteins are presumed to interact with effector molecules and may be involved in dimerisation [PMID: 8516313].

The known structure of MarA (P27246) shows that the AraC domain is alpha helical and shows the two HTH subdomains both bind the major groove of the DNA. The two HTH subdomains are separated by only 27 angstroms, which causes the cognate DNA to bend.

This entry representsthe full AraC domain containing the two HTH subdomains.

GO terms

Biological Process

GO:0006355 regulation of transcription, DNA-templated

Molecular Function

GO:0003700 DNA-binding transcription factor activity
GO:0043565 sequence-specific DNA binding

Cellular Component

No terms assigned in this category.

Contributing signatures

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