4X4M

Structure of FcgammaRI in complex with Fc reveals the importance of glycan recognition for high affinity IgG binding


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.485 Å
  • R-Value Free: 0.296 
  • R-Value Work: 0.245 

wwPDB Validation 3D Report Full Report


This is version 1.0 of the entry. See complete history

Literature

Structure of Fc gamma RI in complex with Fc reveals the importance of glycan recognition for high-affinity IgG binding.

Lu, J.Chu, J.Zou, Z.Hamacher, N.B.Rixon, M.W.Sun, P.D.

(2015) Proc.Natl.Acad.Sci.USA 112: 833-838

  • DOI: 10.1073/pnas.1418812112

  • PubMed Abstract: 
  • Fc gamma receptor I (FcγRI) contributes to protective immunity against bacterial infections, but exacerbates certain autoimmune diseases. The sole high-affinity IgG receptor, FcγRI plays a significant role in immunotherapy. To elucidate the molecular ...

    Fc gamma receptor I (FcγRI) contributes to protective immunity against bacterial infections, but exacerbates certain autoimmune diseases. The sole high-affinity IgG receptor, FcγRI plays a significant role in immunotherapy. To elucidate the molecular mechanism of its high-affinity IgG binding, we determined the crystal structure of the extracellular domains of human FcγRI in complex with the Fc domain of human IgG1. FcγRI binds to the Fc in a similar mode as the low-affinity FcγRII and FcγRIII receptors. In addition to many conserved contacts, FcγRI forms additional hydrogen bonds and salt bridges with the lower hinge region of Fc. Unique to the high-affinity receptor-Fc complex, however, is the conformation of the receptor D2 domain FG loop, which enables a charged KHR motif to interact with proximal carbohydrate units of the Fc glycans. Both the length and the charge of the FcγRI FG loop are well conserved among mammalian species. Ala and Glu mutations of the FG loop KHR residues showed significant contributions of His-174 and Arg-175 to antibody binding, and the loss of the FG loop-glycan interaction resulted in an ∼ 20- to 30-fold decrease in FcγRI affinity to all three subclasses of IgGs. Furthermore, deglycosylation of IgG1 resulted in a 40-fold loss in FcγRI binding, demonstrating involvement of the receptor FG loop in glycan recognition. These results highlight a unique glycan recognition in FcγRI function and open potential therapeutic avenues based on antibody glycan engineering or small molecular glycan mimics to target FcγRI for certain autoimmune diseases.


    Organizational Affiliation

    Structural Immunology Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852 and.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Ig gamma-1 chain C region
A, B, C, D
219Homo sapiensMutation(s): 0 
Gene Names: IGHG1
Find proteins for P01857 (Homo sapiens)
Go to UniProtKB:  P01857
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
High affinity immunoglobulin gamma Fc receptor I
E, F
275Homo sapiensMutation(s): 18 
Gene Names: FCGR1A (FCG1, FCGR1, IGFR1)
Find proteins for P12314 (Homo sapiens)
Go to Gene View: FCGR1A
Go to UniProtKB:  P12314
Small Molecules
Ligands 6 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
MAN
Query on MAN

Download SDF File 
Download CCD File 
A, B, C, D
ALPHA-D-MANNOSE
C6 H12 O6
WQZGKKKJIJFFOK-PQMKYFCFSA-N
 Ligand Interaction
GAL
Query on GAL

Download SDF File 
Download CCD File 
C, D
BETA-D-GALACTOSE
C6 H12 O6
WQZGKKKJIJFFOK-FPRJBGLDSA-N
 Ligand Interaction
BMA
Query on BMA

Download SDF File 
Download CCD File 
A, B, C, D
BETA-D-MANNOSE
C6 H12 O6
WQZGKKKJIJFFOK-RWOPYEJCSA-N
 Ligand Interaction
NAG
Query on NAG

Download SDF File 
Download CCD File 
A, B, C, D
N-ACETYL-D-GLUCOSAMINE
C8 H15 N O6
OVRNDRQMDRJTHS-FMDGEEDCSA-N
 Ligand Interaction
FUL
Query on FUL

Download SDF File 
Download CCD File 
A, B, C, D
BETA-L-FUCOSE
6-DEOXY-BETA-L-GALACTOSE
C6 H12 O5
SHZGCJCMOBCMKK-KGJVWPDLSA-N
 Ligand Interaction
SIA
Query on SIA

Download SDF File 
Download CCD File 
D
O-SIALIC ACID
C11 H19 N O9
SQVRNKJHWKZAKO-YRMXFSIDSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.485 Å
  • R-Value Free: 0.296 
  • R-Value Work: 0.245 
  • Space Group: P 1
Unit Cell:
Length (Å)Angle (°)
a = 59.921α = 89.86
b = 67.991β = 112.25
c = 125.028γ = 89.96
Software Package:
Software NamePurpose
PHENIXrefinement
SCALAdata scaling
PHASERphasing
HKL-2000data reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

  • Deposited Date: 2014-12-03 
  • Released Date: 2015-04-08 
  • Deposition Author(s): Lu, J., Sun, P.D.

Revision History 

  • Version 1.0: 2015-04-08
    Type: Initial release