title: Crystal structure of the transcriptional regulator AcrR from Escherichia coli.
abstract: The AcrAB multidrug efflux pump, which belongs to the resistance nodulation division (RND) family, recognizes and extrudes a wide range of antibiotics and chemotherapeutic agents and causes the intrinsic antibiotic resistance in Escherichia coli. The expression of AcrAB is controlled by the transcriptional regulator AcrR, whose open reading frame is located 141 bp upstream of the acrAB operon. To understand the structural basis of AcrR regulation, we have determined the crystal structure of AcrR to 2.55-A resolution, revealing a dimeric two-domain molecule with an entirely helical architecture similar to members of the TetR family of transcriptional regulators. Each monomer of AcrR forms a multientrance pocket of 350 A(3) in the ligand-binding domain. The ligand-binding pocket is surrounded with mostly hydrophobic residues. In addition, a completely buried negatively charged glutamate, expected to be critical for drug binding, is located at the center of the binding pocket. The crystal structure provides novel insight into the mechanisms of ligand binding and AcrR regulation.
authors.affiliation: Department of Physics and Astronomy, Iowa State University, Ames, IA 50011, USA.
authors.forename: Ming
authors.initials: M
authors.lastname: Li
authors.forename: Ruoyu
authors.initials: R
authors.lastname: Gu
authors.forename: Chih-Chia
authors.initials: CC
authors.lastname: Su
authors.forename: Mathew D
authors.initials: MD
authors.lastname: Routh
authors.forename: Katherine C
authors.initials: KC
authors.lastname: Harris
authors.forename: Elizabeth S
authors.initials: ES
authors.lastname: Jewell
authors.forename: Gerry
authors.initials: G
authors.lastname: McDermott
authors.forename: Edward W
authors.initials: EW
authors.lastname: Yu
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D002850:Chromatography, Gel; D018360:Crystallography, X-Ray; D017931:DNA Primers; D004269:DNA, Bacterial / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism; D005454:Fluorescence Polarization; D008024:Ligands; D008958:Models, Molecular; D011487:Protein Conformation; D012097:Repressor Proteins / Q000737:chemistry* / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry* / Q000378:metabolism
chemical_list: C515217:AcrR protein, E coli; D017931:DNA Primers; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D008024:Ligands; D012097:Repressor Proteins; D014157:Transcription Factors