2Q0O

Crystal structure of an anti-activation complex in bacterial quorum sensing

Summary for 2Q0O

• Entry DOI: 10.2210/pdb2q0o/pdb
• Descriptor: Probable transcriptional activator protein traR, Probable transcriptional repressor traM, 3-OXO-OCTANOIC ACID (2-OXO-TETRAHYDRO-FURAN-3-YL)-AMIDE, ... (4 entities in total)
• Functional Keywords: helix-turn-helix, two-helix coiled coil, transcription
• Biological source: Rhizobium sp.; More
• Total number of polymer chains: 4
• Total formula weight: 77562.21

Authors

Chen, G.,Jeffrey, P.D.,Fuqua, C.,Shi, Y.,Chen, L. (deposition date: 2007-05-22, release date: 2007-09-25, Last modification date: 2023-08-30)

Primary citation

Chen, G.,Jeffrey, P.D.,Fuqua, C.,Shi, Y.,Chen, L.
Structural basis for antiactivation in bacterial quorum sensing.
Proc.Natl.Acad.Sci.Usa, 104:16474-16479, 2007

PubMed Abstract: Bacteria can communicate via diffusible signal molecules they generate and release to coordinate their behavior in response to the environment. Signal molecule concentration is often proportional to bacterial population density, and when this reaches a critical concentration, reflecting a bacterial quorum, specific behaviors including virulence, symbiosis, and horizontal gene transfer are activated. Quorum-sensing regulation in many Gram-negative bacteria involves acylated homoserine lactone signals that are perceived through binding to LuxR-type, acylated-homoserine-lactone-responsive transcription factors. Bacteria of the rhizobial group employ the LuxR-type transcriptional activator TraR in quorum sensing, and its activity is further regulated through interactions with the TraM antiactivator. In this study, we have crystallographically determined the 3D structure of the TraR-TraM antiactivation complex from Rhizobium sp. strain NGR234. Unexpectedly, the antiactivator TraM binds to TraR at a site distinct from its DNA-binding motif and induces an allosteric conformational change in the protein, thereby preventing DNA binding. Structural analysis reveals a highly conserved TraR-TraM interface and suggests a mechanism for antiactivation complex formation. This structure may inform alternative strategies to control quorum-sensing-regulated microbial activity including amelioration of infectious disease and antibiotic resistance. In addition, the structural basis of antiactivation presents a regulatory interaction that provides general insights relevant to the field of transcription regulation and signal transduction.

PubMed: 17921255
DOI: 10.1073/pnas.0704843104

Experimental method

X-RAY DIFFRACTION (2 Å)