2B4M

Crystal structure of the binding protein OpuAC in complex with proline betaine


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.80 Å
  • R-Value Free: 0.283 
  • R-Value Work: 0.231 

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This is version 1.3 of the entry. See complete history


Literature

Molecular Determinants for Substrate Specificity of the Ligand-binding Protein OpuAC from Bacillus subtilis for the Compatible Solutes Glycine Betaine and Proline Betaine.

Horn, C.Sohn-Boesser, L.Breed, J.Welte, W.Schmitt, L.Bremer, E.

(2006) J Mol Biol 357: 592-606

  • DOI: https://doi.org/10.1016/j.jmb.2005.12.085
  • Primary Citation of Related Structures:  
    2B4L, 2B4M

  • PubMed Abstract: 

    Compatible solutes play a decisive role in the defense of microorganisms against changes in temperature and increases in osmolarity in their natural habitats. In Bacillus subtilis, the substrate-binding protein (SBP)-dependent ABC-transporter OpuA serves for the uptake of the compatible solutes glycine betaine (GB) and proline betaine (PB). Here, we report the determinants of compatible solute binding by OpuAC, the SBP of the OpuA transporter, by equilibrium binding studies and X-ray crystallography. The affinity of OpuAC/GB and OpuAC/PB complexes were analyzed by intrinsic tryptophan fluorescence and the K(D) values were determined to be 17(+/-1)microM for GB and 295(+/-27)microM for PB, respectively. The structures of OpuAC in complex with GB or PB were solved at 2.0 A and 2.8 A, respectively, and show an SBP-typical class II fold. The ligand-binding pocket is formed by three tryptophan residues arranged in a prism-like geometry suitable to coordinate the positive charge of the trimethyl ammonium group of GB and the dimethyl ammonium group of PB by cation-pi interactions and by hydrogen bonds with the carboxylate moiety of the ligand. Structural differences between the OpuAC/GB and OpuAC/PB complexes occur within the ligand-binding pocket as well as across the domain-domain interface. These differences provide a structural framework to explain the drastic differences in affinity of the OpuAC/GB and OpuAC/PB complexes. A sequence comparison with putative SBP specific for compatible solutes reveals the presence of three distinct families for which the crystal structure of OpuAC might serve as a suitable template to predict the structures of these putative compatible solute-binding proteins.


  • Organizational Affiliation

    Institute of Biochemistry, Heinrich Heine University Duesseldorf, Universitaetsstr. 1, 40225 Duesseldorf, Germany.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Glycine betaine-binding protein
A, B
268Bacillus subtilisMutation(s): 0 
Gene Names: opuAC
UniProt
Find proteins for P46922 (Bacillus subtilis (strain 168))
Explore P46922 
Go to UniProtKB:  P46922
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP46922
Sequence Annotations
Expand
  • Reference Sequence
Small Molecules
Binding Affinity Annotations 
IDSourceBinding Affinity
PBE PDBBind:  2B4M Kd: 2.95e+5 (nM) from 1 assay(s)
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.80 Å
  • R-Value Free: 0.283 
  • R-Value Work: 0.231 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 88.562α = 90
b = 28.318β = 93.87
c = 102.826γ = 90
Software Package:
Software NamePurpose
REFMACrefinement
HKL-2000data reduction
SCALEPACKdata scaling
AMoREphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2006-03-21
    Type: Initial release
  • Version 1.1: 2008-05-01
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Advisory, Version format compliance
  • Version 1.3: 2023-08-23
    Changes: Data collection, Database references, Derived calculations, Refinement description