5HU6

Structure of the T. brucei haptoglobin-haemoglobin receptor bound to human haptolgobin-haemoglobin


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.90 Å
  • R-Value Free: 0.226 
  • R-Value Work: 0.190 
  • R-Value Observed: 0.192 

wwPDB Validation   3D Report Full Report


This is version 1.1 of the entry. See complete history

Re-refinement Note

This entry reflects an alternative modeling of the original data in:4X0I


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

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

  • 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 ...

    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
Hemoglobin subunit alpha A141Homo sapiensMutation(s): 0 
Gene Names: HBA1HBA2
Find proteins for P69905 (Homo sapiens)
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Go to UniProtKB:  P69905
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PHAROS:  P69905
Protein Feature View
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  • Reference Sequence
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Entity ID: 2
MoleculeChainsSequence LengthOrganismDetailsImage
Hemoglobin subunit beta B141Homo sapiensMutation(s): 0 
Gene Names: HBB
Find proteins for P68871 (Homo sapiens)
Explore P68871 
Go to UniProtKB:  P68871
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PHAROS:  P68871
Protein Feature View
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  • Reference Sequence
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Entity ID: 3
MoleculeChainsSequence LengthOrganismDetailsImage
Haptoglobin C259Homo sapiensMutation(s): 0 
Gene Names: HP
Find proteins for P00738 (Homo sapiens)
Explore P00738 
Go to UniProtKB:  P00738
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PHAROS:  P00738
Protein Feature View
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  • Reference Sequence
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Entity ID: 4
MoleculeChainsSequence LengthOrganismDetailsImage
Haptoglobin-hemoglobin receptor D260Trypanosoma brucei bruceiMutation(s): 0 
Gene Names: HpHbR
Find proteins for Q581F2 (Trypanosoma brucei brucei (strain 927/4 GUTat10.1))
Explore Q581F2 
Go to UniProtKB:  Q581F2
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
HEM
Query on HEM

Download Ideal Coordinates CCD File 
A, B
PROTOPORPHYRIN IX CONTAINING FE
C34 H32 Fe N4 O4
KABFMIBPWCXCRK-RGGAHWMASA-L
 Ligand Interaction
NAG
Query on NAG

Download Ideal Coordinates CCD File 
C
2-acetamido-2-deoxy-beta-D-glucopyranose
C8 H15 N O6
OVRNDRQMDRJTHS-FMDGEEDCSA-N
 Ligand Interaction
OXY
Query on OXY

Download Ideal Coordinates CCD File 
A, B
OXYGEN MOLECULE
O2
MYMOFIZGZYHOMD-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.90 Å
  • R-Value Free: 0.226 
  • R-Value Work: 0.190 
  • R-Value Observed: 0.192 
  • Space Group: C 1 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 222.29α = 90
b = 56.56β = 92.97
c = 66.1γ = 90
Software Package:
Software NamePurpose
BUSTERrefinement
iMOSFLMdata reduction
SCALAdata scaling
PHASERphasing

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2016-03-02
    Type: Initial release
  • Version 1.1: 2020-07-29
    Type: Remediation
    Reason: Carbohydrate remediation
    Changes: Data collection, Derived calculations, Structure summary