4R4H

Crystal structure of non-neutralizing, A32-like antibody 2.2c in complex with HIV-1 Env gp120


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 4.28 Å
  • R-Value Free: 0.320 
  • R-Value Work: 0.309 
  • R-Value Observed: 0.310 

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This is version 1.3 of the entry. See complete history


Literature

Structural Definition of an Antibody-Dependent Cellular Cytotoxicity Response Implicated in Reduced Risk for HIV-1 Infection.

Acharya, P.Tolbert, W.D.Gohain, N.Wu, X.Yu, L.Liu, T.Huang, W.Huang, C.C.Kwon, Y.D.Louder, R.K.Luongo, T.S.McLellan, J.S.Pancera, M.Yang, Y.Zhang, B.Flinko, R.Foulke, J.S.Sajadi, M.M.Kamin-Lewis, R.Robinson, J.E.Martin, L.Kwong, P.D.Guan, Y.DeVico, A.L.Lewis, G.K.Pazgier, M.

(2014) J Virol 88: 12895-12906

  • DOI: https://doi.org/10.1128/JVI.02194-14
  • Primary Citation of Related Structures:  
    4H8W, 4R4B, 4R4F, 4R4H, 4R4N

  • PubMed Abstract: 

    The RV144 vaccine trial implicated epitopes in the C1 region of gp120 (A32-like epitopes) as targets of potentially protective antibody-dependent cellular cytotoxicity (ADCC) responses. A32-like epitopes are highly immunogenic, as infected or vaccinated individuals frequently produce antibodies specific for these determinants. Antibody titers, as measured by enzyme-linked immunosorbent assay (ELISA) against these epitopes, however, do not consistently correlate with protection. Here, we report crystal structures of CD4-stabilized gp120 cores complexed with the Fab fragments of two nonneutralizing, A32-like monoclonal antibodies (MAbs), N5-i5 and 2.2c, that compete for antigen binding and have similar antigen-binding affinities yet exhibit a 75-fold difference in ADCC potency. We find that these MAbs recognize overlapping epitopes formed by mobile layers 1 and 2 of the gp120 inner domain, including the C1 and C2 regions, but bind gp120 at different angles via juxtaposed VH and VL contact surfaces. A comparison of structural and immunological data further showed that antibody orientation on bound antigen and the capacity to form multivalent antigen-antibody complexes on target cells were key determinants of ADCC potency, with the latter process having the greater impact. These studies provide atomic-level definition of A32-like epitopes implicated as targets of protective antibodies in RV144. Moreover, these studies establish that epitope structure and mode of antibody binding can dramatically affect the potency of Fc-mediated effector function against HIV-1. These results provide key insights for understanding, refining, and improving the outcome of HIV vaccine trials, in which relevant immune responses are facilitated by A32-like elicited responses. HIV-1 Env is a primary target for antibodies elicited during infection. Although a small number of infected individuals elicit broadly neutralizing antibodies, the bulk of the humoral response consists of antibodies that do not neutralize or do so with limited breadth but may effect protection through Fc receptor-dependent processes, such as antibody-dependent cellular cytotoxicity (ADCC). Understanding these nonneutralizing responses is an important aspect of elucidating the complete spectrum of immune response against HIV-1 infection. With this report, we provide the first atomic-level definition of nonneutralizing CD4-induced epitopes in the N-terminal region of the HIV-1 gp120 (A32-like epitopes). Further, our studies point to the dominant role of precise epitope targeting and mode of antibody attachment in ADCC responses even when largely overlapping epitopes are involved. Such information provides key insights into the mechanisms of Fc-mediated function of antibodies to HIV-1 and will help us understand the outcome of vaccine trials based on humoral immunity.


  • Organizational Affiliation

    Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA.


Macromolecules
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Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
HIV-1 Env gp120433Human immunodeficiency virus 1Mutation(s): 0 
UniProt
Find proteins for Q73372 (Human immunodeficiency virus type 1 group M subtype B (strain 89.6))
Explore Q73372 
Go to UniProtKB:  Q73372
Entity Groups  
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UniProt GroupQ73372
Glycosylation
Glycosylation Sites: 6
Sequence Annotations
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  • Reference Sequence
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Entity ID: 2
MoleculeChains Sequence LengthOrganismDetailsImage
T-cell surface glycoprotein CD4178Homo sapiensMutation(s): 0 
Gene Names: CD4
UniProt & NIH Common Fund Data Resources
Find proteins for P01730 (Homo sapiens)
Explore P01730 
Go to UniProtKB:  P01730
PHAROS:  P01730
GTEx:  ENSG00000010610 
Entity Groups  
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UniProt GroupP01730
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  • Reference Sequence
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Entity ID: 3
MoleculeChains Sequence LengthOrganismDetailsImage
Antibody 2.2c, Light chainC [auth L]210Homo sapiensMutation(s): 0 
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  • Reference Sequence
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Entity ID: 4
MoleculeChains Sequence LengthOrganismDetailsImage
Antibody 2.2c, Heavy chainD [auth H]220Homo sapiensMutation(s): 0 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
Glycosylation
Glycosylation Sites: 1
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 4.28 Å
  • R-Value Free: 0.320 
  • R-Value Work: 0.309 
  • R-Value Observed: 0.310 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 61.357α = 90
b = 69.429β = 90
c = 328.576γ = 90
Software Package:
Software NamePurpose
HKL-2000data collection
PHASERphasing
PHENIXrefinement
HKL-2000data reduction
HKL-2000data scaling

Structure Validation

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Ligand Structure Quality Assessment 


Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2014-09-17
    Type: Initial release
  • Version 1.1: 2014-10-22
    Changes: Database references
  • Version 1.2: 2018-01-31
    Changes: Experimental preparation
  • Version 1.3: 2020-07-29
    Type: Remediation
    Reason: Carbohydrate remediation
    Changes: Data collection, Derived calculations, Structure summary