5CIP

Crystal Structure of Unbound 4E10


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.48 Å
  • R-Value Free: 0.231 
  • R-Value Work: 0.183 
  • R-Value Observed: 0.185 

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This is version 1.4 of the entry. See complete history


Literature

Structural and Thermodynamic Basis of Epitope Binding by Neutralizing and Nonneutralizing Forms of the Anti-HIV-1 Antibody 4E10

Rujas, E.Gulzar, N.Morante, K.Tsumoto, K.Scott, J.K.Nieva, J.L.Caaveiro, J.M.M.

(2015) J Virol 89: 11975-11989

  • DOI: https://doi.org/10.1128/JVI.01793-15
  • Primary Citation of Related Structures:  
    5CIL, 5CIN, 5CIP

  • PubMed Abstract: 

    The 4E10 antibody recognizes the membrane-proximal external region (MPER) of the HIV-1 Env glycoprotein gp41 transmembrane subunit, exhibiting one of the broadest neutralizing activities known to date. The neutralizing activity of 4E10 requires solvent-exposed hydrophobic residues at the apex of the complementarity-determining region (CDR) H3 loop, but the molecular basis for this requirement has not been clarified. Here, we report the cocrystal structures and the energetic parameters of binding of a peptide bearing the 4E10-epitope sequence (4E10ep) to nonneutralizing versions of the 4E10 Fab. Nonneutralizing Fabs were obtained by shortening and decreasing the hydrophobicity of the CDR-H3 loop (termed ΔLoop) or by substituting the two tryptophan residues of the CDR-H3 apex with Asp residues (termed WDWD), which also decreases hydrophobicity but preserves the length of the loop. The analysis was complemented by the first crystal structure of the 4E10 Fab in its ligand-free state. Collectively, the data ruled out major conformational changes of CDR-H3 at any stage during the binding process (equilibrium or transition state). Although these mutations did not impact the affinity of wild-type Fab for the 4E10ep in solution, the two nonneutralizing versions of 4E10 were deficient in binding to MPER inserted in the plasma membrane (mimicking the environment faced by the antibody in vivo). The conclusions of our structure-function analysis strengthen the idea that to exert effective neutralization, the hydrophobic apex of the solvent-exposed CDR-H3 loop must recognize an antigenic structure more complex than just the linear α-helical epitope and likely constrained by the viral membrane lipids.


  • Organizational Affiliation

    Department of Bioengineering, Graduate School of Engineering, The University of Tokyo, Tokyo, Japan Biophysics Unit (CSIC, UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), Bilbao, Spain.


Macromolecules
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Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
FAB 4E10 HEAVY CHAINA [auth H]227Homo sapiensMutation(s): 0 
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Entity ID: 2
MoleculeChains Sequence LengthOrganismDetailsImage
FAB 4E10 LIGHT CHAINB [auth L],
D [auth B]
212Homo sapiensMutation(s): 0 
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Entity ID: 3
MoleculeChains Sequence LengthOrganismDetailsImage
FAB 4E10 HEAVY CHAINC [auth A]226Homo sapiensMutation(s): 0 
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.48 Å
  • R-Value Free: 0.231 
  • R-Value Work: 0.183 
  • R-Value Observed: 0.185 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 44.66α = 90
b = 134.17β = 105.8
c = 81.86γ = 90
Software Package:
Software NamePurpose
REFMACrefinement
MOSFLMdata reduction
SCALAdata scaling
PHASERphasing

Structure Validation

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Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
National Institutes of Health/National Institute Of Allergy and Infectious Diseases (NIH/NIAID)United States1R01AI097051-01
Japan Society for the Promotion of ScienceJapan25249115

Revision History  (Full details and data files)

  • Version 1.0: 2015-09-23
    Type: Initial release
  • Version 1.1: 2015-11-18
    Changes: Database references
  • Version 1.2: 2017-10-18
    Changes: Author supporting evidence, Data collection, Database references, Derived calculations
  • Version 1.3: 2022-03-23
    Changes: Author supporting evidence, Database references
  • Version 1.4: 2023-11-08
    Changes: Data collection, Refinement description