native structure of conglutinin carbohydrate recognition domain

Experimental Data Snapshot

  • Resolution: 0.97 Å
  • R-Value Free: 0.139 
  • R-Value Work: 0.135 
  • R-Value Observed: 0.135 

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Atomic-resolution crystal structures of the immune protein conglutinin from cow reveal specific interactions of its binding site withN-acetylglucosamine.

Paterson, J.M.Shaw, A.J.Burns, I.Dodds, A.W.Prasad, A.Reid, K.B.Greenhough, T.J.Shrive, A.K.

(2019) J Biol Chem 294: 17155-17165

  • DOI: https://doi.org/10.1074/jbc.RA119.010271
  • Primary Citation of Related Structures:  
    6RYG, 6RYJ, 6RYM, 6RYN

  • PubMed Abstract: 

    Bovine conglutinin is an immune protein that is involved in host resistance to microbes and parasites and interacts with complement component iC3b, agglutinates erythrocytes, and neutralizes influenza A virus. Here, we determined the high-resolution (0.97-1.46 Å) crystal structures with and without bound ligand of a recombinant fragment of conglutinin's C-terminal carbohydrate-recognition domain (CRD). The structures disclosed that the high-affinity ligand N -acetyl-d-glucosamine (GlcNAc) binds in the collectin CRD calcium site by interacting with the O3' and O4' hydroxyls alongside additional specific interactions of the N -acetyl group oxygen and nitrogen with Lys-343 and Asp-320, respectively. These residues, unique to conglutinin and differing both in sequence and in location from those in other collectins, result in specific, high-affinity binding for GlcNAc. The binding pocket flanking residue Val-339, unlike the equivalent Arg-343 in the homologous human surfactant protein D, is sufficiently small to allow conglutinin Lys-343 access to the bound ligand, whereas Asp-320 lies in an extended loop proximal to the ligand-binding site and bounded at both ends by conserved residues that coordinate to both calcium and ligand. This loop becomes ordered on ligand binding. The electron density revealed both α and β anomers of GlcNAc, consistent with the added α/βGlcNAc mixture. Crystals soaked with α1-2 mannobiose, a putative component of iC3b, reported to bind to conglutinin, failed to reveal bound ligand, suggesting a requirement for presentation of mannobiose as part of an extended physiological ligand. These results reveal a highly specific GlcNAc-binding pocket in conglutinin and a novel collectin mode of carbohydrate recognition.

  • Organizational Affiliation

    School of Life Sciences, Keele University, Staffordshire ST5 5BG, United Kingdom.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Conglutinin128Bos taurusMutation(s): 0 
Gene Names: CGN1
Find proteins for P23805 (Bos taurus)
Explore P23805 
Go to UniProtKB:  P23805
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP23805
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
CA (Subject of Investigation/LOI)
Query on CA

Download Ideal Coordinates CCD File 
Experimental Data & Validation

Experimental Data

Unit Cell:
Length ( Å )Angle ( ˚ )
a = 50.17α = 90
b = 50.17β = 90
c = 52.247γ = 90
Software Package:
Software NamePurpose
MOSFLMdata reduction
SCALAdata scaling
PDB_EXTRACTdata extraction

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2019-10-09
    Type: Initial release
  • Version 1.1: 2019-11-20
    Changes: Database references
  • Version 1.2: 2024-01-24
    Changes: Data collection, Database references, Refinement description