Experimental Data Snapshot

  • Resolution: 1.90 Å
  • R-Value Free: 0.246 
  • R-Value Work: 0.204 

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The Structure of the Outer Membrane Protein Ompx from Escherichia Coli Reveals Mechanisms of Virulence

Vogt, J.Schulz, G.E.

(1999) Structure 7: 1301

  • DOI: https://doi.org/10.1016/s0969-2126(00)80063-5
  • Primary Citation of Related Structures:  
    1QJ8, 1QJ9

  • PubMed Abstract: 

    The integral outer membrane protein X (OmpX) from Escherichia coli belongs to a family of highly conserved bacterial proteins that promote bacterial adhesion to and entry into mammalian cells. Moreover, these proteins have a role in the resistance against attack by the human complement system. Here we present the first crystal structure of a member of this family. The crystal structure of OmpX from E. coli was determined at 1.9 A resolution using multiple isomorphous replacement. OmpX consists of an eight-stranded antiparallel all-next-neighbor beta barrel. The structure shows two girdles of aromatic amino acid residues and a ribbon of nonpolar residues that attach to the membrane interior. The core of the barrel consists of an extended hydrogen-bonding network of highly conserved residues. OmpX thus resembles an inverse micelle. The structure explains the dramatically improved crystal quality of OmpX containing the mutation His100-->Asn, which made the X-ray analysis possible. The coordination spheres of two bound platinum ions are described. The OmpX structure shows that within a family of virulence-related membrane proteins, the membrane-spanning part of the protein is much better conserved than the extracellular loops. Moreover, these loops form a protruding beta sheet, the edge of which presumably binds to external proteins. It is suggested that this type of binding promotes cell adhesion and invasion and helps defend against the complement system. Although OmpX has the same beta-sheet topology as the structurally related outer membrane protein A (OmpA), their barrels differ with respect to the shear numbers and internal hydrogen-bonding networks.

  • Organizational Affiliation

    Institut für Organische Chemie und Biochemie, Albert-Ludwigs-Universität, Albertstrasse 21, D-79104, Freiburg im Breisgau, Germany.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
OUTER MEMBRANE PROTEIN X148Escherichia coliMutation(s): 1 
Gene Names: OMPX
Membrane Entity: Yes 
Find proteins for P0A917 (Escherichia coli (strain K12))
Explore P0A917 
Go to UniProtKB:  P0A917
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP0A917
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.90 Å
  • R-Value Free: 0.246 
  • R-Value Work: 0.204 
  • Space Group: H 3 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 82.4α = 90
b = 82.4β = 90
c = 206.3γ = 120
Software Package:
Software NamePurpose
MOSFLMdata reduction
SCALAdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1999-10-10
    Type: Initial release
  • Version 1.1: 2011-05-08
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2019-07-24
    Changes: Data collection
  • Version 1.4: 2024-05-08
    Changes: Data collection, Database references, Derived calculations, Other