5OD0

Crystal structure of ACPA E4


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.80 Å
  • R-Value Free: 0.213 
  • R-Value Work: 0.170 
  • R-Value Observed: 0.172 

Starting Model: experimental
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wwPDB Validation   3D Report Full Report


This is version 2.2 of the entry. See complete history


Literature

Structural Basis of Cross-Reactivity of Anti-Citrullinated Protein Antibodies.

Ge, C.Xu, B.Liang, B.Lonnblom, E.Lundstrom, S.L.Zubarev, R.A.Ayoglu, B.Nilsson, P.Skogh, T.Kastbom, A.Malmstrom, V.Klareskog, L.Toes, R.E.M.Rispens, T.Dobritzsch, D.Holmdahl, R.

(2019) Arthritis Rheumatol 71: 210-221

  • DOI: https://doi.org/10.1002/art.40698
  • Primary Citation of Related Structures:  
    5OCK, 5OCX, 5OCY, 5OD0, 5OD8, 5ODB

  • PubMed Abstract: 

    Anti-citrullinated protein antibodies (ACPAs) develop many years before the clinical onset of rheumatoid arthritis (RA). This study was undertaken to address the molecular basis of the specificity and cross-reactivity of ACPAs from patients with RA. Antibodies isolated from RA patients were expressed as monoclonal chimeric antibodies with mouse Fc. These antibodies were characterized for glycosylation using mass spectrometry, and their cross-reactivity was assessed using Biacore and Luminex immunoassays. The crystal structures of the antigen-binding fragment (Fab) of the monoclonal ACPA E4 in complex with 3 different citrullinated peptides were determined using x-ray crystallography. The prevalence of autoantibodies reactive against 3 of the citrullinated peptides that also interacted with E4 was investigated by Luminex immunoassay in 2 Swedish cohorts of RA patients. Analysis of the crystal structures of a monoclonal ACPA from human RA serum in complex with citrullinated peptides revealed key residues of several complementarity-determining regions that recognized the citrulline as well as the neighboring peptide backbone, but with limited contact with the side chains of the peptides. The same citrullinated peptides were recognized by high titers of serum autoantibodies in 2 large cohorts of RA patients. These data show, for the first time, how ACPAs derived from human RA serum recognize citrulline. The specific citrulline recognition and backbone-mediated interactions provide a structural explanation for the promiscuous recognition of citrullinated peptides by RA-specific ACPAs.


  • Organizational Affiliation

    Karolinska Institutet, Stockholm, Sweden.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Fab fragment of ACPA E4 - Light chainA [auth L]216Homo sapiensMutation(s): 0 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
Sequence Annotations
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  • Reference Sequence
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 2
MoleculeChains Sequence LengthOrganismDetailsImage
Fab fragment of ACPA E4 - heavy chainB [auth H]220Homo sapiensMutation(s): 0 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
Sequence Annotations
Expand
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.80 Å
  • R-Value Free: 0.213 
  • R-Value Work: 0.170 
  • R-Value Observed: 0.172 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 54.91α = 90
b = 62.05β = 90
c = 124.02γ = 90
Software Package:
Software NamePurpose
REFMACrefinement
xia2data reduction
XSCALEdata scaling
PHASERphasing

Structure Validation

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Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
Knut and Alice Wallenberg FoundationSwedenKAW 2010.0148
Swedish Research CouncilSweden2015-02662

Revision History  (Full details and data files)

  • Version 1.0: 2018-07-04
    Type: Initial release
  • Version 1.1: 2019-08-07
    Changes: Data collection, Database references
  • Version 2.0: 2020-03-11
    Changes: Database references, Polymer sequence
  • Version 2.1: 2024-01-17
    Changes: Data collection, Database references, Refinement description
  • Version 2.2: 2024-10-16
    Changes: Structure summary