1E6O

Crystal structure of Fab13B5 against HIV-1 capsid protein p24


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.80 Å
  • R-Value Free: 0.255 
  • R-Value Work: 0.225 
  • R-Value Observed: 0.225 

Starting Model: experimental
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This is version 1.4 of the entry. See complete history


Literature

Mutual Conformational Adaptations in Antigen and Antibody Upon Complex Formation between an Fab and HIV-1 Capsid Protein P24

Monaco-Malbet, S.Berthet-Colominas, C.Novelli, A.Battai, N.Piga, N.Cheynet, V.Mallet, F.Cusack, S.

(2000) Structure 8: 1069

  • DOI: https://doi.org/10.1016/s0969-2126(00)00507-4
  • Primary Citation of Related Structures:  
    1E6J, 1E6O

  • PubMed Abstract: 

    Elucidating the structural basis of antigen-antibody recognition ideally requires a structural comparison of free and complexed components. To this end we have studied a mouse monoclonal antibody, denoted 13B5, raised against p24, the capsid protein of HIV-1. We have previously described the first crystal structure of intact p24 as visualized in the Fab13B5-p24 complex. Here we report the structure of the uncomplexed Fab13B5 at 1.8 A resolution and analyze the Fab-p24 interface and the conformational changes occurring upon complex formation. Fab13B5 recognizes a nearly continuous epitope comprising a helix-turn-helix motif in the C-terminal domain of p24. Only 4 complementarity-determining regions (CDRs) are in contact with p24 with most interactions being by the heavy chain. Comparison of the free and complexed Fab reveals that structural changes upon binding are localized to a few side chains of CDR-H1 and -H2 but involve a larger, concerted displacement of CDR-H3. Antigen binding is also associated with an 8 degrees relative rotation of the heavy and light chain variable regions. In p24, small conformational changes localized to the turn between the two helices comprising the epitope result from Fab binding. The relatively small area of contact between Fab13B5 and p24 may be related to the fact that the epitope is a continuous peptide rather than a more complex protein surface and correlates with a relatively low affinity of antigen and antibody. Despite this, a significant quaternary structural change occurs in the Fab upon complex formation, with additional smaller adaptations of both antigen and antibody.


  • Organizational Affiliation

    European Molecular Laboratory Biology Grenoble Outstation B.P. 156X F-38042 Cedex 9, Grenoble, France.


Macromolecules
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Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
IMMUNOGLOBULIN HEAVY CHAINA [auth H]219Mus musculusMutation(s): 0 
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Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
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  • Reference Sequence
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Entity ID: 2
MoleculeChains Sequence LengthOrganismDetailsImage
IMMUNOGLOBULIN LIGHT CHAINB [auth L]212Mus musculusMutation(s): 0 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.80 Å
  • R-Value Free: 0.255 
  • R-Value Work: 0.225 
  • R-Value Observed: 0.225 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 36.68α = 90
b = 81.9β = 90
c = 134.4γ = 90
Software Package:
Software NamePurpose
X-PLORrefinement
MOSFLMdata reduction
SCALAdata scaling
X-PLORphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2000-11-27
    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: 2019-05-08
    Changes: Advisory, Data collection, Experimental preparation, Other
  • Version 1.4: 2023-12-13
    Changes: Advisory, Data collection, Database references, Other, Refinement description