|PROSITE documentation PDOC00542 [for PROSITE entry PS50043]|
The luxR-type HTH domain is a DNA-binding, helix-turn-helix (HTH) domain of about 65 amino acids, present in transcription regulators of the LuxR/FixJ family of response regulators. The domain is named after Vibrio fischeri luxR, a transcriptional activator for quorum-sensing control of luminescence. LuxR-type HTH domain proteins occur in bacteria and in chloroplasts of algae. The DNA-binding HTH domain is usually located in the C-terminal part; the N-terminal part can contain an autoinducer binding domain or a response regulatory domain (see <PDOC50110>). Most luxR-type regulators act as transcription activators, but some can be repressors or have a dual role for different sites. LuxR-type HTH regulators control a wide variety of activities in various biological processes.
Several structures of luxR-type HTH proteins have been resolved and show that the DNA-binding domain is formed by a four-helix bundle (see <PDB:1P4W>). The helix-turn-helix motif comprises the second and third helices, which are being called the scaffold and the recognition helix, respectively. The HTH is involved in DNA-binding into the major groove, where the N-terminal part of the recognition helix makes most DNA-contacts. The fourth helix is involved in dimerization of gerE and traR. Signalling events by one of the four activation mechanisms described below lead to multimerization of the regulator. The regulators bind DNA as multimers [1,2,3,4].
LuxR-type HTH proteins can be activated by one of four different mechanisms:
I. Regulators which belong to a two-component sensory transduction system where the protein is activated by its phosphorylation, generally on an aspartate residue, by a transmembrane kinase. Some proteins that belong to this category are:
II. Regulators which are activated when bound to autoinducer molecules such as N-(3-oxohexanoyl)-L-homoserine lactone (OHHL) (see <PDOC00731>), a mechanism which can be involved in quorum sensing systems. Some proteins that belong to this category are:
III. Autonomous effector domain regulators, without a regulatory domain, represented by gerE .
IV. Multiple ligands binding regulators, exemplified by malT.
The 'helix-turn-helix' DNA-binding motif of these proteins is located in the C-terminal section of the sequence. The pattern we use to detect these proteins starts three residues downstream of the N-terminal extremity of the helix-turn-helix motif and extends one residue downstream of its C-terminal extremity. We also developed a profile that covers the entire luxR-type HTH DNA-binding domain, including helices 1 and 4, and which allows a more sensitive detection.Last update:
April 2006 / Pattern revised.
PROSITE methods (with tools and information) covered by this documentation:
|1||Authors||Egland K.A., Greenberg E.P.|
|Title||Quorum sensing in Vibrio fischeri: analysis of the LuxR DNA binding region by alanine-scanning mutagenesis.|
|Source||J. Bacteriol. 183:382-386(2001).|
|2||Authors||Ducros V.M.-A., Lewis R.J., Verma C.S., Dodson E.J., Leonard G., Turkenburg J.P., Murshudov G.N., Wilkinson A.J., Brannigan J.A.|
|Title||Crystal structure of GerE, the ultimate transcriptional regulator of spore formation in Bacillus subtilis.|
|Source||J. Mol. Biol. 306:759-771(2001).|
|3||Authors||Vannini A., Volpari C., Gargioli C., Muraglia E., Cortese R., De Francesco R., Neddermann P., Marco S.D.|
|Title||The crystal structure of the quorum sensing protein TraR bound to its autoinducer and target DNA.|
|Source||EMBO J. 21:4393-4401(2002).|
|4||Authors||Pristovsek P., Sengupta K., Lohr F., Schafer B., von Trebra M.W., Ruterjans H., Bernhard F.|
|Title||Structural analysis of the DNA-binding domain of the Erwinia amylovora RcsB protein and its interaction with the RcsAB box.|
|Source||J. Biol. Chem. 278:17752-17759(2003).|