4X0L

Human haptoglobin-haemoglobin complex


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.05 Å
  • R-Value Free: 0.224 
  • R-Value Work: 0.180 
  • R-Value Observed: 0.182 

wwPDB Validation 3D Report Full Report



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
  • Structures With Same Primary Citation

  • 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 structur ...

    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

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Hemoglobin subunit alphaA141Homo sapiensMutation(s): 0 
Gene Names: HBA1HBA2
Find proteins for P69905 (Homo sapiens)
Explore P69905 
Go to UniProtKB:  P69905
NIH Common Fund Data Resources
PHAROS  P69905
Protein Feature View
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  • Reference Sequence

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Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
Hemoglobin subunit betaB146Homo sapiensMutation(s): 0 
Gene Names: HBB
Find proteins for P68871 (Homo sapiens)
Explore P68871 
Go to UniProtKB:  P68871
NIH Common Fund Data Resources
PHAROS  P68871
Protein Feature View
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  • Reference Sequence

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Entity ID: 3
MoleculeChainsSequence LengthOrganismDetails
HaptoglobinC259Homo sapiensMutation(s): 0 
Gene Names: HP
Find proteins for P00738 (Homo sapiens)
Explore P00738 
Go to UniProtKB:  P00738
NIH Common Fund Data Resources
PHAROS  P00738
Protein Feature View
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  • Reference Sequence
Oligosaccharides
Entity ID: 4
MoleculeChainsChain Length2D Diagram Glycosylation
alpha-L-fucopyranose-(1-6)-2-acetamido-2-deoxy-beta-D-glucopyranose
D
2 N-Glycosylation
Small Molecules
Ligands 5 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
HEM
Query on HEM

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

Download CCD File 
C
CACODYLATE ION
C2 H6 As O2
OGGXGZAMXPVRFZ-UHFFFAOYSA-M
 Ligand Interaction
SO4
Query on SO4

Download CCD File 
C
SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
 Ligand Interaction
GOL
Query on GOL

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B, C
GLYCEROL
C3 H8 O3
PEDCQBHIVMGVHV-UHFFFAOYSA-N
 Ligand Interaction
OXY
Query on OXY

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

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.05 Å
  • R-Value Free: 0.224 
  • R-Value Work: 0.180 
  • R-Value Observed: 0.182 
  • Space Group: P 31 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 96.599α = 90
b = 96.599β = 90
c = 132.771γ = 120
Software Package:
Software NamePurpose
REFMACrefinement
MOSFLMdata reduction
SCALAdata scaling
PHASERphasing

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History 

  • 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
  • Version 2.0: 2020-07-29
    Type: Remediation
    Reason: Carbohydrate remediation
    Changes: Atomic model, Data collection, Derived calculations, Source and taxonomy, Structure summary