To improve security and privacy, we are moving our web pages and services from HTTP to HTTPS.
To give users of web services time to transition to HTTPS, we will support separate HTTP and HTTPS services until the end of 2017.
From January 2018 most HTTP traffic will be automatically redirected to HTTPS. [more...]
View this page in https
PROSITE documentation PDOC50943

Cro/C1-type HTH domain profile





Description

The cro/C1-type HTH domain is a DNA-binding, helix-turn-helix (HTH) domain of about 50-60 residues present in transcriptional regulators. The domain is named after the transcriptional repressors cro and C1 of temperate bacteriophages 434 and lambda, respectively. Besides in bacteriophages, cro/C1-type regulators are present in prokaryotes and in eukaryotes. The helix-turn-helix DNA-binding motif is generally located in the N-terminal part of these transcriptional regulators. The C-terminal part may contain an oligomerization domain, e.g. C1 repressors and CopR act as dimers, while SinR is a tetramer. The cro/C1-type HTH domain also occurs in combination with the TPR repeat and the C-terminal part of C-5 cytosine-specific DNA methylases contains regions related to the enzymatic function (see <PDOC00089>).

Several structures of cro/C1-type transcriptional repressors have been resolved and their DNA-binding domain encompasses five α helices, of which the extremities are less conserved (see <PDB:2OR1>) [1]. The helix-turn-helix motif comprises the second and third helices, the third being called the recognition helix. The HTH is involved in DNA-binding into the major groove, where the recognition helix makes most DNA-contacts. The bacteriophage repressors regulate lysogeny/lytic growth by binding with differential affinity to the operators. These operators show 2-fold symmetry and the repressors bind as dimers. Binding of the repressor to the operator positions the DNA backbone into a slightly bent twist [1,2].

Some proteins known to contain a cro/C1-type HTH domain:

  • Bacteriophage 434 cro and C1, transcriptional repressors that bind to the operator DNA. Upon induction, proteases in the bacterial host cleave the C1 dimerization domain from the DNA-binding domain, so that genes for the lytic pathway are no longer repressed.
  • PBSX xre, a repressor protein of the defective prophage in Bacillus.
  • Bacillus subtilis sinR, a transcriptional repressor for inhibition of sporulation. The structure and function are related to phage repressors [3].
  • Bombyx mori (Silk moth) MBF1, multiprotein bridging factor 1, a transcriptional coactivator that mediates transcriptional activation by connecting a general and a gene-specific transcription factor. MBF1 is conserved in eukaryotes from yeast to human [4,5].
  • Plasmid pIP501 copR, a transcriptional repressor and activator involved in plasmid copy number regulation.
  • Escherichia coli nadR, a transcriptional regulator of early NAD biosynthetic genes.
  • Dictyostelium discoideum (Slime mold) H7, a vegetative specific protein which is deactivated upon the initiation of development.

The profile we developed covers the entire DNA-binding domain, from the major part of helix 1, including the helix-turn-helix motif and the major part of helix 5.

Last update:

November 2003 / First entry.

Technical section

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

HTH_CROC1, PS50943; Cro/C1-type HTH domain profile  (MATRIX)


References

1AuthorsAggarwal A.K., Rodgers D.W., Drottar M., Ptashne M., Harrison S.C.
TitleRecognition of a DNA operator by the repressor of phage 434: a view at high resolution.
SourceScience 242:899-907(1988).
PubMed ID3187531

2AuthorsSteinmetzer K., Behlke J., Brantl S., Lorenz M.
TitleCopR binds and bends its target DNA: a footprinting and fluorescence resonance energy transfer study.
SourceNucleic Acids Res. 30:2052-2060(2002).
PubMed ID11972345

3AuthorsLewis R.J., Brannigan J.A., Offen W.A., Smith I., Wilkinson A.J.
TitleAn evolutionary link between sporulation and prophage induction in the structure of a repressor:anti-repressor complex.
SourceJ. Mol. Biol. 283:907-912(1998).
PubMed ID9799632

4AuthorsTakemaru K., Li F.Q., Ueda H., Hirose S.
TitleMultiprotein bridging factor 1 (MBF1) is an evolutionarily conserved transcriptional coactivator that connects a regulatory factor and TATA element-binding protein.
SourceProc. Natl. Acad. Sci. U.S.A. 94:7251-7256(1997).
PubMed ID9207077

5AuthorsKabe Y., Goto M., Shima D., Imai T., Wada T., Morohashi K., Shirakawa M., Hirose S., Handa H.
TitleThe role of human MBF1 as a transcriptional coactivator.
SourceJ. Biol. Chem. 274:34196-34202(1999).
PubMed ID10567391



PROSITE is copyright. It is produced by the SIB Swiss Institute Bioinformatics. There are no restrictions on its use by non-profit institutions as long as its content is in no way modified. Usage by and for commercial entities requires a license agreement. For information about the licensing scheme send an email to
Prosite License or see: prosite_license.html.

Miscellaneous

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