4E40

The haptoglobin-hemoglobin receptor of Trypanosoma congolense


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.6 Å
  • R-Value Free: 0.223 
  • R-Value Work: 0.206 

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.USA 110: 1905-1910

  • DOI: 10.1073/pnas.1214943110

  • 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 med ...

    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: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Putative uncharacterized protein
A
252Trypanosoma congolense (strain IL3000)Mutation(s): 0 
Find proteins for G0UVW6 (Trypanosoma congolense (strain IL3000))
Go to UniProtKB:  G0UVW6
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.6 Å
  • R-Value Free: 0.223 
  • R-Value Work: 0.206 
  • Space Group: P 65 2 2
Unit Cell:
Length (Å)Angle (°)
a = 104.530α = 90.00
b = 104.530β = 90.00
c = 113.070γ = 120.00
Software Package:
Software NamePurpose
SHARPphasing
REFMACrefinement
DNAdata collection
SCALAdata scaling
MOSFLMdata reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

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