4X0J

Trypanosoma brucei haptoglobin-haemoglobin receptor


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.85 Å
  • R-Value Free: 0.240 
  • R-Value Work: 0.199 
  • R-Value Observed: 0.201 

wwPDB Validation   3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

Structural basis for ligand and innate immunity factor uptake by the trypanosome haptoglobin-haemoglobin receptor.

Lane-Serff, H.MacGregor, P.Lowe, E.D.Carrington, M.Higgins, M.K.

(2014) Elife 3: e05553-e05553

  • DOI: 10.7554/eLife.05553
  • Primary Citation of Related Structures:  
    4X0J, 4X0L, 5HU6

  • PubMed Abstract: 
  • The haptoglobin-haemoglobin receptor (HpHbR) of African trypanosomes allows acquisition of haem and provides an uptake route for trypanolytic factor-1, a mediator of innate immunity against trypanosome infection. In this study, we report the structure of Trypanosoma brucei HpHbR in complex with human haptoglobin-haemoglobin (HpHb), revealing an elongated ligand-binding site that extends along its membrane distal half ...

    The haptoglobin-haemoglobin receptor (HpHbR) of African trypanosomes allows acquisition of haem and provides an uptake route for trypanolytic factor-1, a mediator of innate immunity against trypanosome infection. In this study, we report the structure of Trypanosoma brucei HpHbR in complex with human haptoglobin-haemoglobin (HpHb), revealing an elongated ligand-binding site that extends along its membrane distal half. This contacts haptoglobin and the β-subunit of haemoglobin, showing how the receptor selectively binds HpHb over individual components. Lateral mobility of the glycosylphosphatidylinositol-anchored HpHbR, and a ∼50° kink in the receptor, allows two receptors to simultaneously bind one HpHb dimer. Indeed, trypanosomes take up dimeric HpHb at significantly lower concentrations than monomeric HpHb, due to increased ligand avidity that comes from bivalent binding. The structure therefore reveals the molecular basis for ligand and innate immunity factor uptake by trypanosomes and identifies adaptations that allow efficient ligand uptake in the context of the complex trypanosome cell surface.


    Organizational Affiliation

    Department of Biochemistry, University of Oxford, Oxford, United Kingdom.



Macromolecules
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Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Haptoglobin-hemoglobin receptorA, B265Trypanosoma brucei bruceiMutation(s): 0 
Gene Names: HpHbR
UniProt
Find proteins for I7BA99 (Trypanosoma brucei brucei)
Explore I7BA99 
Go to UniProtKB:  I7BA99
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupI7BA99
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.85 Å
  • R-Value Free: 0.240 
  • R-Value Work: 0.199 
  • R-Value Observed: 0.201 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 27.9α = 90
b = 47.79β = 92.79
c = 203.38γ = 90
Software Package:
Software NamePurpose
REFMACrefinement
MOSFLMdata reduction
SCALAdata scaling
PHASERphasing

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2014-12-24
    Type: Initial release
  • Version 1.1: 2015-01-21
    Changes: Database references
  • Version 1.2: 2015-03-04
    Changes: Database references