4F33

Crystal Structure of therapeutic antibody MORAb-009


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.75 Å
  • R-Value Free: 0.234 
  • R-Value Work: 0.208 
  • R-Value Observed: 0.208 

wwPDB Validation   3D Report Full Report


This is version 2.0 of the entry. See complete history


Literature

Recognition of mesothelin by the therapeutic antibody MORAb-009: structural and mechanistic insights.

Ma, J.Tang, W.K.Esser, L.Pastan, I.Xia, D.

(2012) J Biol Chem 287: 33123-33131

  • DOI: https://doi.org/10.1074/jbc.M112.381756
  • Primary Citation of Related Structures:  
    4F33, 4F3F

  • PubMed Abstract: 

    Mesothelin is a tumor differentiation antigen that is highly expressed in many epithelial cancers, with limited expression in normal human tissues. Binding of mesothelin on normal mesothelial cells lining the pleura or peritoneum to the tumor-associated cancer antigen 125 (CA-125) can lead to heterotypic cell adhesion and tumor metastasis within the pleural and peritoneal cavities. This binding can be prevented by MORAb-009, a humanized monoclonal antibody against mesothelin currently under clinical trials. We show here that MORAb-009 recognizes a non-linear epitope that is contained in the first 64-residue fragment of the mesothelin. We further demonstrate that the recognition is independent of glycosylation state of the protein but sensitive to the loss of a disulfide bond linking residues Cys-7 and Cys-31. The crystal structure of the complex between the mesothelin N-terminal fragment and Fab of MORAb-009 at 2.6 Å resolution reveals an epitope encompassing multiple secondary structural elements of the mesothelin, including residues from helix α1, the loops linking helices α1 and α2, and between helices α4 and α5. The mesothelin fragment has a compact, right-handed superhelix structure consisting of five short helices and connecting loops. A residue essential for complex formation has been identified as Phe-22, which projects its side chain into a hydrophobic niche formed on the antibody recognition surface upon antigen-antibody contact. The overlapping binding footprints of both the monoclonal antibody and the cancer antigen CA-125 explains the therapeutic effect and provides a basis for further antibody improvement.


  • Organizational Affiliation

    Laboratory of Cell Biology, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland 20892, USA.


Macromolecules
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Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
MORAb-009 FAB light chain
A, C, E, G
213Mus musculusMutation(s): 0 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
Sequence Annotations
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  • Reference Sequence
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Entity ID: 2
MoleculeChains Sequence LengthOrganismDetailsImage
MORAb-009 FAB heavy chain
B, D, F, H
231Mus musculusMutation(s): 0 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
Sequence Annotations
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  • Reference Sequence
Small Molecules
Modified Residues  1 Unique
IDChains TypeFormula2D DiagramParent
PCA
Query on PCA
B, D, F, H
L-PEPTIDE LINKINGC5 H7 N O3GLN
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.75 Å
  • R-Value Free: 0.234 
  • R-Value Work: 0.208 
  • R-Value Observed: 0.208 
  • Space Group: P 41 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 141.311α = 90
b = 141.311β = 90
c = 281.528γ = 90
Software Package:
Software NamePurpose
HKL-2000data collection
BALBESphasing
PHENIXrefinement
DENZOdata reduction
SCALEPACKdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2012-07-11
    Type: Initial release
  • Version 1.1: 2013-09-25
    Changes: Source and taxonomy
  • Version 1.2: 2014-03-26
    Changes: Database references
  • Version 2.0: 2019-12-25
    Changes: Derived calculations, Polymer sequence