6TCM

Crystal structure of the omalizumab Fab - crystal form I

Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.85 Å
  • R-Value Free: 0.190 
  • R-Value Work: 0.168 
  • R-Value Observed: 0.169 

wwPDB Validation   3D Report Full Report


This is version 1.0 of the entry. See complete history. 


Literature

Engineering the Fab fragment of the anti-IgE omalizumab to prevent Fab crystallization and permit IgE-Fc complex crystallization.

Mitropoulou, A.N., Ceska, T., Heads, J.T., Beavil, A.J., Henry, A.J., McDonnell, J.M., Sutton, B.J., Davies, A.M.

(2020) Acta Crystallogr F Struct Biol Commun 76: 116-129

  • DOI: 10.1107/S2053230X20001466
  • Primary Citation of Related Structures:  
    6TCM, 6TCN, 6TCO, 6TCP, 6TCQ, 6TCR, 6TCS

  • PubMed Abstract: 

    • Immunoglobulin E (IgE) plays a central role in the allergic response, in which cross-linking of allergen by FcεRI-bound IgE triggers mast cell and basophil degranulation and the release of inflammatory mediators. The high-affinity interaction between IgE and FcεRI is a long-standing target for therapeutic intervention in allergic disease ...

    Immunoglobulin E (IgE) plays a central role in the allergic response, in which cross-linking of allergen by FcεRI-bound IgE triggers mast cell and basophil degranulation and the release of inflammatory mediators. The high-affinity interaction between IgE and FcεRI is a long-standing target for therapeutic intervention in allergic disease. Omalizumab is a clinically approved anti-IgE monoclonal antibody that binds to free IgE, also with high affinity, preventing its interaction with FcεRI. All attempts to crystallize the pre-formed complex between the omalizumab Fab and the Fc region of IgE (IgE-Fc), to understand the structural basis for its mechanism of action, surprisingly failed. Instead, the Fab alone selectively crystallized in different crystal forms, but their structures revealed intermolecular Fab/Fab interactions that were clearly strong enough to disrupt the Fab/IgE-Fc complexes. Some of these interactions were common to other Fab crystal structures. Mutations were therefore designed to disrupt two recurring packing interactions observed in the omalizumab Fab crystal structures without interfering with the ability of the omalizumab Fab to recognize IgE-Fc; this led to the successful crystallization and subsequent structure determination of the Fab/IgE-Fc complex. The mutagenesis strategy adopted to achieve this result is applicable to other intractable Fab/antigen complexes or systems in which Fabs are used as crystallization chaperones.

    Organizational Affiliation: 

    Randall Centre for Cell and Molecular Biophysics, King's College London, New Hunt's House, London SE1 1UL, UK.



Macromolecules
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Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Omalizumab FabA [auth L]218Homo sapiensMutation(s): 0 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
Protein Feature View
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  • Reference Sequence
Find similar proteins by: 
(by identity cutoff)  |  3D Structure
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetailsImage
Omalizumab FabB [auth H]230Homo sapiensMutation(s): 0 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
Protein Feature View
Expand
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.85 Å
  • R-Value Free: 0.190 
  • R-Value Work: 0.168 
  • R-Value Observed: 0.169 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 65.375α = 90
b = 73.555β = 90
c = 141.099γ = 90
Software Package:
Software NamePurpose
PHENIXrefinement
PDB_EXTRACTdata extraction
XDSdata reduction
Aimlessdata scaling
MOLREPphasing

Structure Validation

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Entry History & Funding Information

Deposition Data

Funding OrganizationLocationGrant Number
Medical Research Council (United Kingdom)United KingdomG1100090
Wellcome TrustUnited Kingdom085944

Revision History  (Full details and data files)

  • Version 1.0: 2020-03-18
    Type: Initial release