helix_turn_helix, arabinose operon control protein
SMART accession number:SM00342
Description: -
Interpro abstract (IPR018060):

Many bacterial transcription regulation proteins bind DNA through a 'helix-turn-helix' (HTH) motif. One major subfamily of these proteins [ (PUBMED:8451183) (PUBMED:2314271) ] is related to the arabinose operon regulatory protein AraC [ (PUBMED:8451183) (PUBMED:2314271) . Except for celD [ (PUBMED: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 [ (PUBMED: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 process:regulation of transcription, DNA-templated (GO:0006355)
GO function:DNA-binding transcription factor activity (GO:0003700), sequence-specific DNA binding (GO:0043565)
Family alignment:
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There are 344050 HTH_ARAC domains in 343647 proteins in SMART's nrdb database.

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