PROSITE documentation PDOC51118
HxlR-type HTH domain profile


The hxlR-type HTH domain is a domain of ~90-100 amino acids present in putative transcription regulators with a winged helix-turn-helix (wHTH) structure. The domain is named after Bacillus subtilis hxlR, a transcription activator of the hxlAB operon involved in the detoxification of formaldehyde [1]. The hxlR-type domain forms the core of putative transcription regulators and of hypothetical proteins occurring in eubacteria as well as in archaea. The sequence and structure of hxlR-type proteins show similarities with the marR-type wHTH (see <PDOC00861>) [2].

The crystal structure of ytfH resembles the DNA-binding domains of winged helix proteins (see <PDB:1YYV>), containing a three helix (H) bundle and a three-stranded antiparallel β-sheet (B) in the topology: H1-H2-B1-H3-H4-B2-B3-H5-H6. This topology corresponds with that of the marR-type DNA-binding domain, wherein helices 3 and 4 comprise the helix-turn-helix motif and the β-sheet is called the wing.

Some proteins known to contain a hxlR-type HTH domain:

  • Bacillus subtilis hxlR, a transcription activator for enzymes of the ribulose monophosphate pathway, which can be induced by formaldehyde.
  • Escherichia coli and Salmonella typhimurium ytfH, a hypothetical protein.
  • Fusobacterium mortiferum malR, a potential regulator of the malBH operon involved in the metabolism of sucrose isomers [3].

The profile we developed covers the entire hxlR-type HTH domain.

Last update:

April 2005 / First entry.


Technical section

PROSITE method (with tools and information) covered by this documentation:

HTH_HXLR, PS51118; HxlR-type HTH domain profile  (MATRIX)


1AuthorsYasueda H. Kawahara Y. Sugimoto S.
TitleBacillus subtilis yckG and yckF encode two key enzymes of the ribulose monophosphate pathway used by methylotrophs, and yckH is required for their expression.
SourceJ. Bacteriol. 181:7154-7160(1999).
PubMed ID10572115

2AuthorsHuffman J.L. Brennan R.G.
TitleProkaryotic transcription regulators: more than just the helix-turn-helix motif.
SourceCurr. Opin. Struct. Biol. 12:98-106(2002).
PubMed ID11839496

3AuthorsPikis A. Immel S. Robrish S.A. Thompson J.
TitleMetabolism of sucrose and its five isomers by Fusobacterium mortiferum.
SourceMicrobiology 148:843-852(2002).
PubMed ID11882720

PROSITE is copyrighted by the SIB Swiss Institute of Bioinformatics and distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives (CC BY-NC-ND 4.0) License, see prosite_license.html.


View entry in original PROSITE document format
View entry in raw text format (no links)