2UXH

TtgR in complex with Quercetin


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.40 Å
  • R-Value Free: 0.295 
  • R-Value Work: 0.237 
  • R-Value Observed: 0.242 

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This is version 1.1 of the entry. See complete history


Literature

Crystal Structures of Multidrug Binding Protein Ttgr in Complex with Antibiotics and Plant Antimicrobials.

Alguel, Y.Meng, C.Teran, W.Krell, T.Ramos, J.L.Gallegos, M.-T.Zhang, X.

(2007) J Mol Biol 369: 829

  • DOI: https://doi.org/10.1016/j.jmb.2007.03.062
  • Primary Citation of Related Structures:  
    2UXH, 2UXI, 2UXO, 2UXP, 2UXU

  • PubMed Abstract: 

    Antibiotic resistance is a widely spread phenomenon. One major mechanism that underlies antibiotic resistance in bacteria is the active extrusion of toxic compounds through the membrane-bound efflux pumps that are often regulated at the transcriptional level. TtgR represses the transcription of TtgABC, a key efflux pump in Pseudomonas putida, which is highly resistant to antibiotics, solvents and toxic plant secondary products. Previously we showed that TtgR is the only reported repressor that binds to different classes of natural antimicrobial compounds, which are also extruded by the efflux pump. We report here five high-resolution crystal structures of TtgR from the solvent-tolerant strain DOT-T1E, including TtgR in complex with common antibiotics and plant secondary metabolites. We provide structural basis for the unique ligand binding properties of TtgR. We identify two distinct and overlapping ligand binding sites; the first one is broader and consists of mainly hydrophobic residues, whereas the second one is deeper and contains more polar residues including Arg176, a unique residue present in the DOT-T1E strain but not in other Pseudomonas strains. Phloretin, a plant antimicrobial, can bind to both binding sites with distinct binding affinities and stoichiometries. Results on ligand binding properties of native and mutant TtgR proteins using isothermal titration calorimetry confirm the binding affinities and stoichiometries, and suggest a potential positive cooperativity between the two binding sites. The importance of Arg176 in phloretin binding was further confirmed by the reduced ability of phloretin in releasing the mutant TtgR from bound DNA compared to the native protein. The results presented here highlight the importance and versatility of regulatory systems in bacterial antibiotic resistance and open up new avenues for novel antimicrobial development.


  • Organizational Affiliation

    Centre for Structural Biology and Division of Molecular Biosciences, Imperial College London, London, SW7 2AZ, UK.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
HTH-TYPE TRANSCRIPTIONAL REGULATOR TTGR
A, B
210Pseudomonas putidaMutation(s): 0 
UniProt
Find proteins for Q9AIU0 (Pseudomonas putida (strain DOT-T1E))
Explore Q9AIU0 
Go to UniProtKB:  Q9AIU0
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ9AIU0
Sequence Annotations
Expand
  • Reference Sequence
Small Molecules
Binding Affinity Annotations 
IDSourceBinding Affinity
QUE BindingDB:  2UXH -TΔS: min: -1.18e+1, max: 61.02 (kJ/mol) from 4 assay(s)
ΔG: min: -3.38e+1, max: -2.93e+1 (kJ/mol) from 4 assay(s)
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.40 Å
  • R-Value Free: 0.295 
  • R-Value Work: 0.237 
  • R-Value Observed: 0.242 
  • Space Group: P 21 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 46.65α = 90
b = 231.881β = 90
c = 44.33γ = 90
Software Package:
Software NamePurpose
REFMACrefinement
SCALEPACKdata scaling
CNSphasing

Structure Validation

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Ligand Structure Quality Assessment 


Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2007-05-08
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Advisory, Version format compliance