2J6E

Crystal Structure of an Autoimmune Complex between a Human IgM Rheumatoid Factor and IgG1 Fc reveals a Novel Fc Epitope and Evidence for Affinity Maturation


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 3 Å
  • R-Value Free: 0.288 
  • R-Value Work: 0.223 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Crystal Structure of a Human Autoimmune Complex between Igm Rheumatoid Factor Rf61 and Igg1 Fc Reveals a Novel Epitope and Evidence for Affinity Maturation.

Duquerroy, S.Stura, E.A.Bressanelli, S.Fabiane, S.M.Vaney, M.-C.Beale, D.Hamon, M.Casali, P.Rey, F.A.Sutton, B.J.Taussig, M.J.

(2007) J.Mol.Biol. 368: 1321

  • DOI: 10.1016/j.jmb.2007.02.085

  • PubMed Abstract: 
  • Rheumatoid factors (RF) are autoantibodies that recognize epitopes in the Fc region of immunoglobulin (Ig) G and that correlate with the clinical severity of rheumatoid arthritis (RA). Here we report the X-ray crystallographic structure, at 3 A resol ...

    Rheumatoid factors (RF) are autoantibodies that recognize epitopes in the Fc region of immunoglobulin (Ig) G and that correlate with the clinical severity of rheumatoid arthritis (RA). Here we report the X-ray crystallographic structure, at 3 A resolution, of a complex between the Fc region of human IgG1 and the Fab fragment of a monoclonal IgM RF (RF61), derived from an RA patient and with a relatively high affinity for IgG Fc. In the complex, two Fab fragments bind to each Fc at epitopes close to the C terminus, and each epitope comprises residues from both Cgamma3 domains. A central role in the unusually hydrophilic epitope is played by the side-chain of Arg355, accounting for the subclass specificity of RF61, which recognizes IgG1,-2, and -3 in preference to IgG4, in which the corresponding residue is Gln355. Compared with a previously determined complex of a lower affinity RF (RF-AN) bound to IgG4 Fc, in which only residues at the very edge of the antibody combining site were involved in binding, the epitope bound by RF61 is centered in classic fashion on the axis of the V(H):V(L) beta-barrel. The complementarity determining region-H3 loop plays a key role, forming a pocket in which Arg355 is bound by two salt-bridges. The antibody contacts also involve two somatically mutated V(H) residues, reinforcing the suggestion of a process of antigen-driven maturation and selection for IgG Fc during the generation of this RF autoantibody.


    Organizational Affiliation

    Virologie Mol├ęculaire et Structurale, CNRS UMR 2472-INRA UMR 1157, 91198 Gif-sur-Yvette, France.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
IG GAMMA-1 CHAIN C REGION
A, B
232Homo sapiensGene Names: IGHG1
Find proteins for P01857 (Homo sapiens)
Go to UniProtKB:  P01857
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
IGM
H, I
231N/AN/A
Protein Feature View is not available: No corresponding UniProt sequence found.
Entity ID: 3
MoleculeChainsSequence LengthOrganismDetails
IGM
L, M
234N/AN/A
Protein Feature View is not available: No corresponding UniProt sequence found.
Small Molecules
Ligands 11 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
ZN
Query on ZN

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A, B
ZINC ION
Zn
PTFCDOFLOPIGGS-UHFFFAOYSA-N
 Ligand Interaction
ACT
Query on ACT

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A, B, H
ACETATE ION
C2 H3 O2
QTBSBXVTEAMEQO-UHFFFAOYSA-M
 Ligand Interaction
MAN
Query on MAN

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A, B
ALPHA-D-MANNOSE
C6 H12 O6
WQZGKKKJIJFFOK-PQMKYFCFSA-N
 Ligand Interaction
GAL
Query on GAL

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A, B
BETA-D-GALACTOSE
C6 H12 O6
WQZGKKKJIJFFOK-FPRJBGLDSA-N
 Ligand Interaction
BMA
Query on BMA

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A, B
BETA-D-MANNOSE
C6 H12 O6
WQZGKKKJIJFFOK-RWOPYEJCSA-N
 Ligand Interaction
NDG
Query on NDG

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A
2-(ACETYLAMINO)-2-DEOXY-A-D-GLUCOPYRANOSE
C8 H15 N O6
OVRNDRQMDRJTHS-PVFLNQBWSA-N
 Ligand Interaction
CAC
Query on CAC

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A
CACODYLATE ION
dimethylarsinate
C2 H6 As O2
OGGXGZAMXPVRFZ-UHFFFAOYSA-M
 Ligand Interaction
NAG
Query on NAG

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A, B
N-ACETYL-D-GLUCOSAMINE
C8 H15 N O6
OVRNDRQMDRJTHS-FMDGEEDCSA-N
 Ligand Interaction
FUL
Query on FUL

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A, B
BETA-L-FUCOSE
6-DEOXY-BETA-L-GALACTOSE
C6 H12 O5
SHZGCJCMOBCMKK-KGJVWPDLSA-N
 Ligand Interaction
MPD
Query on MPD

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A, B, M
(4S)-2-METHYL-2,4-PENTANEDIOL
C6 H14 O2
SVTBMSDMJJWYQN-YFKPBYRVSA-N
 Ligand Interaction
CD
Query on CD

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A
CADMIUM ION
Cd
WLZRMCYVCSSEQC-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 3 Å
  • R-Value Free: 0.288 
  • R-Value Work: 0.223 
  • Space Group: C 1 2 1
Unit Cell:
Length (Å)Angle (°)
a = 241.980α = 90.00
b = 75.610β = 91.13
c = 102.400γ = 90.00
Software Package:
Software NamePurpose
CNSrefinement
DENZOdata reduction
AMoREphasing
SCALEPACKdata scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2007-04-10
    Type: Initial release
  • Version 1.1: 2011-05-08
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance