3HW9

Cation selective pathway of OmpF porin revealed by anomalous x-ray diffraction


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.61 Å
  • R-Value Free: 0.300 
  • R-Value Work: 0.229 
  • R-Value Observed: 0.232 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history


Literature

Cation-selective pathway of OmpF porin revealed by anomalous X-ray diffraction.

Dhakshnamoorthy, B.Raychaudhury, S.Blachowicz, L.Roux, B.

(2010) J Mol Biol 396: 293-300

  • DOI: 10.1016/j.jmb.2009.11.042
  • Structures With Same Primary Citation

  • PubMed Abstract: 
  • The OmpF porin from the Escherichia coli outer membrane folds into a trimer of beta-barrels, each forming a wide aqueous pore allowing the passage of ions and small solutes. A long loop (L3) carrying multiple acidic residues folds into the beta-barre ...

    The OmpF porin from the Escherichia coli outer membrane folds into a trimer of beta-barrels, each forming a wide aqueous pore allowing the passage of ions and small solutes. A long loop (L3) carrying multiple acidic residues folds into the beta-barrel pore to form a narrow "constriction zone". A strong and highly conserved charge asymmetry is observed at the constriction zone, with multiple basic residues attached to the wall of the beta-barrel (Lys16, Arg42, Arg82 and Arg132) on one side, and multiple acidic residues of L3 (Asp107, Asp113, Glu117, Asp121, Asp126, Asp127) on the other side. Several computational studies have suggested that a strong transverse electric field could exist at the constriction zone as a result of such charge asymmetry, giving rise to separate permeation pathways for cations and anions. To examine this question, OmpF was expressed, purified and crystallized in the P6(3) space group and two different data sets were obtained at 2.6 A and 3.0 A resolution with K(+) and Rb(+), respectively. The Rb(+)-soaked crystals were collected at the rubidium anomalous wavelength of 0.8149 A and cation positions were determined. A PEG molecule was observed in the pore region for both the K(+) and Rb(+)-soaked crystals, where it interacts with loop L3. The results reveal the separate pathways of anions and cations across the constriction zone of the OmpF pore.


    Organizational Affiliation

    Department of Biochemistry and Molecular Biology, Gordon Center for Integrative Science, University of Chicago, Chicago, IL 60637, USA.



Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Outer membrane protein F
A, B
362Escherichia coli K-12Mutation(s): 0 
Gene Names: b0929cmlBcoacryJW0912ompFtolF
Find proteins for P02931 (Escherichia coli (strain K12))
Go to UniProtKB:  P02931
Protein Feature View
  • Reference Sequence
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
P6G
Query on P6G

Download CCD File 
A, B
HEXAETHYLENE GLYCOL
C12 H26 O7
IIRDTKBZINWQAW-UHFFFAOYSA-N
 Ligand Interaction
K
Query on K

Download CCD File 
A, B
POTASSIUM ION
K
NPYPAHLBTDXSSS-UHFFFAOYSA-N
 Ligand Interaction
CL
Query on CL

Download CCD File 
A, B
CHLORIDE ION
Cl
VEXZGXHMUGYJMC-UHFFFAOYSA-M
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.61 Å
  • R-Value Free: 0.300 
  • R-Value Work: 0.229 
  • R-Value Observed: 0.232 
  • Space Group: P 63
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 117.545α = 90
b = 117.545β = 90
c = 121.287γ = 120
Software Package:
Software NamePurpose
HKL-2000data collection
PHASERphasing
REFMACrefinement
HKL-2000data reduction
SCALEPACKdata scaling

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2009-12-08
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance