4E40

The haptoglobin-hemoglobin receptor of Trypanosoma congolense


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.60 Å
  • R-Value Free: 0.223 
  • R-Value Work: 0.206 
  • R-Value Observed: 0.207 

wwPDB Validation   3D Report Full Report


This is version 1.1 of the entry. See complete history


Literature

Structure of the trypanosome haptoglobin-hemoglobin receptor and implications for nutrient uptake and innate immunity.

Higgins, M.K.Tkachenko, O.Brown, A.Reed, J.Raper, J.Carrington, M.

(2013) Proc Natl Acad Sci U S A 110: 1905-1910

  • DOI: 10.1073/pnas.1214943110
  • Primary Citation of Related Structures:  
    4E40

  • PubMed Abstract: 
  • African trypanosomes are protected by a densely packed surface monolayer of variant surface glycoprotein (VSG). A haptoglobin-hemoglobin receptor (HpHbR) within this VSG coat mediates heme acquisition. HpHbR is also exploited by the human host to mediate endocytosis of trypanolytic factor (TLF)1 from serum, contributing to innate immunity ...

    African trypanosomes are protected by a densely packed surface monolayer of variant surface glycoprotein (VSG). A haptoglobin-hemoglobin receptor (HpHbR) within this VSG coat mediates heme acquisition. HpHbR is also exploited by the human host to mediate endocytosis of trypanolytic factor (TLF)1 from serum, contributing to innate immunity. Here, the crystal structure of HpHbR from Trypanosoma congolense has been solved, revealing an elongated three α-helical bundle with a small membrane distal head. To understand the receptor in the context of the VSG layer, the dimensions of Trypanosoma brucei HpHbR and VSG have been determined by small-angle X-ray scattering, revealing the receptor to be more elongated than VSG. It is, therefore, likely that the receptor protrudes above the VSG layer and unlikely that the VSG coat can prevent immunoglobulin binding to the receptor. The HpHb-binding site has been mapped by single-residue mutagenesis and surface plasmon resonance. This site is located where it is readily accessible above the VSG layer. A single HbHpR polymorphism unique to human infective T. brucei gambiense has been shown to be sufficient to reduce binding of both HpHb and TLF1, modulating ligand affinity in a delicate balancing act that allows nutrient acquisition but avoids TLF1 uptake.


    Organizational Affiliation

    Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Putative uncharacterized proteinA252Trypanosoma congolense IL3000Mutation(s): 0 
Gene Names: TCIL3000_10_2930
UniProt
Find proteins for G0UVW6 (Trypanosoma congolense (strain IL3000))
Explore G0UVW6 
Go to UniProtKB:  G0UVW6
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupG0UVW6
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.60 Å
  • R-Value Free: 0.223 
  • R-Value Work: 0.206 
  • R-Value Observed: 0.207 
  • Space Group: P 65 2 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 104.53α = 90
b = 104.53β = 90
c = 113.07γ = 120
Software Package:
Software NamePurpose
DNAdata collection
SHARPphasing
REFMACrefinement
MOSFLMdata reduction
SCALAdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2013-01-16
    Type: Initial release
  • Version 1.1: 2013-02-13
    Changes: Database references