PROSITE documentation PDOC50921
ANTAR domain profile


The ANTAR (AmiR and NasR transcription antitermination regulators) domain is present in bacterial regulatory proteins that are predicted to share the distinct transcription antitermination mechanism reported for amiR and nasR. Three distinct classes of ANTAR-containing proteins have been identified. Most proteins are classical response regulators, where residues comprising an active site are conserved. Therefore, these proteins are predicted to serve as cognate regulators for sensor histidine kinases. Proteins from the second class are predicted to serve as cognate response regulators for sensor histidine kinases. Proteins from the second class are predicted to have a reponse-regulator fold, but lack residues that are essential for phosphotransfer, as in amiR. Finally, some of the ANTAR-containing proteins are predicted to act as a stand-alone sensory transcriptional regulator. In addition to the response regulatory domain (see <PDOC50110>), the ANTAR domain is found associated with GAF, PAC (see <PDOC50112>), STAS (see <PDOC50801>) or NIT (see <PDOC50906>). The ANTAR domain is supposed to be an RNA-binding motif [1].

The structure of the ANTAR domain has been solved (see <PDB:1QO0; D>) and shows that its C-terminus is extended into a substantial α-helix, which participates in a parallel coiled-coil interaction with the equivalent helix of the other monomer. The C-terminus of this helix participates in a three helix bundle. The side chains of the most conserved residues of ANTAR domains are exposed to the cavity formed by the three-helix structure [1,2].

Some proteins known to contain an ANTAR domain are listed below:

  • Pseudomonas aeruginosa aliphatic amidase regulator amiR. It acts as an antiterminator of transcription of the amidase operon by preventing the formation of a termination stem-loop structure when binding ssRNA.
  • Klebsiella oxytoca nitrate regulatory protein nasR. It binds to the factor- independent terminator site located in the nasF operon leader RNA to effect transcription antitermination.
  • Azotobacter vinelandii nasT.

The profile we developed spans the entire ANTAR domain.

Last update:

December 2003 / First entry.


Technical section

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

ANTAR, PS50921; ANTAR domain profile  (MATRIX)


1AuthorsShu C.J. Zhulin I.B.
TitleANTAR: an RNA-binding domain in transcription antitermination regulatory proteins.
SourceTrends Biochem. Sci. 27:3-5(2002).
PubMed ID11796212

2AuthorsO'Hara B.P. Norman R.A. Wan P.T.C. Roe S.M. Barrett T.E. Drew R.E. Pearl L.H.
SourceEMBO J. 18:5175-5186(1999).

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)