3Q5S: Crystal Structure of Bmrr Bound to Acetylcholine

Current views of multidrug (MD) recognition focus on large drug-binding cavities with flexible elements. However, MD recognition in BmrR is supported by a small, rigid drug-binding pocket. Here, a detailed description of MD binding by the noncanonical BmrR protein is offered through the combined use of X-ray and solution studies. Low shape complementarity, suboptimal packing, and efficient burial of a diverse set of ligands is facilitated by an aromatic docking platform formed by a set of conformationally fixed aromatic residues, hydrophobic pincer pair that locks the different drug structures on the adaptable platform surface, and a trio of acidic residues that enables cation selectivity without much regard to ligand structure. Within the binding pocket is a set of BmrR-derived H-bonding donor and acceptors that solvate a wide range of ligand polar substituent arrangements in a manner analogous to aqueous solvent. Energetic analyses of MD binding by BmrR are consistent with structural data. A common binding orientation for the different BmrR ligands is in line with promiscuous allosteric regulation.
PDB ID: 3Q5SDownload
MMDB ID: 91866
PDB Deposition Date: 2010/12/29
Updated in MMDB: 2011/07 
Experimental Method:
x-ray diffraction
Resolution: 3.1  Å
Source Organism:
synthetic construct
Similar Structures:
Biological Unit for 3Q5S: tetrameric; determined by author and by software (PISA)
Molecular Components in 3Q5S
Label Count Molecule
Proteins (2 molecules)
Multidrug-efflux Transporter 1 Regulator(Gene symbol: bmrR)
Molecule annotation
Nucleotide(1 molecule)
23 BP Promoter DNA
Molecule annotation
Chemicals (4 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB