MexR R21W derepressor mutant causing multidrug resistance in P. aeruginosa by mexAB-oprM efflux pump expression

Experimental Data Snapshot

  • Resolution: 2.19 Å
  • R-Value Free: 0.206 
  • R-Value Work: 0.191 
  • R-Value Observed: 0.192 

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Mutation-Induced Population Shift in the Mexr Conformational Ensemble Disengages DNA Binding: A Novel Mechanism for Marr Family Derepression.

Anandapadamanaban, M.Pilstal, R.Andresen, C.Trewhella, J.Moche, M.Wallner, B.Sunnerhagen, M.

(2016) Structure 24: 1311

  • DOI: https://doi.org/10.1016/j.str.2016.06.008
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    MexR is a repressor of the MexAB-OprM multidrug efflux pump operon of Pseudomonas aeruginosa, where DNA-binding impairing mutations lead to multidrug resistance (MDR). Surprisingly, the crystal structure of an MDR-conferring MexR mutant R21W (2.19 Å) presented here is closely similar to wild-type MexR. However, our extended analysis, by molecular dynamics and small-angle X-ray scattering, reveals that the mutation stabilizes a ground state that is deficient of DNA binding and is shared by both mutant and wild-type MexR, whereas the DNA-binding state is only transiently reached by the more flexible wild-type MexR. This population shift in the conformational ensemble is effected by mutation-induced allosteric coupling of contact networks that are independent in the wild-type protein. We propose that the MexR-R21W mutant mimics derepression by small-molecule binding to MarR proteins, and that the described allosteric model based on population shifts may also apply to other MarR family members.

  • Organizational Affiliation

    Division of Chemistry, Department of Physics, Chemistry and Biology, Linköping University, 581 83 Linköping, Sweden.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
A, B
158Pseudomonas aeruginosaMutation(s): 1 
Find proteins for P52003 (Pseudomonas aeruginosa (strain ATCC 15692 / DSM 22644 / CIP 104116 / JCM 14847 / LMG 12228 / 1C / PRS 101 / PAO1))
Explore P52003 
Go to UniProtKB:  P52003
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP52003
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.19 Å
  • R-Value Free: 0.206 
  • R-Value Work: 0.191 
  • R-Value Observed: 0.192 
  • Space Group: P 32 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 84.88α = 90
b = 84.88β = 90
c = 114.187γ = 120
Software Package:
Software NamePurpose
XDSdata reduction
SCALAdata scaling

Structure Validation

View Full Validation Report

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2016-07-27
    Type: Initial release
  • Version 1.1: 2016-08-24
    Changes: Database references
  • Version 1.2: 2024-01-10
    Changes: Data collection, Database references, Derived calculations, Other, Refinement description