2WNK

Structure of SporoSAG from Toxoplasma gondii


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.55 Å
  • R-Value Free: 0.246 
  • R-Value Work: 0.202 
  • R-Value Observed: 0.204 

wwPDB Validation   3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

Structural and Functional Characterization of Sporosag: A Sag2 Related Surface Antigen from Toxoplasma Gondii.

Crawford, J.Lamb, E.Wasmuth, J.Grujic, O.Grigg, M.E.Boulanger, M.J.

(2010) J Biol Chem 285: 12063

  • DOI: https://doi.org/10.1074/jbc.M109.054866
  • Primary Citation of Related Structures:  
    2WNK, 2X28

  • PubMed Abstract: 

    Toxoplasma gondii, the etiological agent of toxoplasmosis, utilizes stage-specific expression of antigenically distinct glycosylphosphatidylinositol-tethered surface coat proteins to promote and establish chronic infection. Of the three infective stages of T. gondii, sporozoites are encapsulated in highly infectious oocysts that have been linked to large scale outbreaks of toxoplasmosis. SporoSAG (surface antigen glycoprotein) is the dominant surface coat protein expressed on the surface of sporozoites. Using a bioinformatic approach, we show that SporoSAG clusters with the SAG2 subfamily of the SAG1-related superfamily (SRS) and is non-polymorphic among the 11 haplogroups of T. gondii strains. In contrast to the immunodominant SAG1 protein expressed on tachyzoites, SporoSAG is non-immunogenic during natural infection. We report the 1.60 A resolution crystal structure of SporoSAG solved using cadmium single anomalous dispersion. SporoSAG crystallized as a monomer and displays unique features of the SRS beta-sandwich fold relative to SAG1 and BSR4. Intriguingly, the structural diversity is localized to the upper sheets of the beta-sandwich fold and may have important implications for multimerization and host cell ligand recognition. The structure of SporoSAG also reveals an unexpectedly acidic surface that contrasts with the previously determined SAG1 and BSR4 structures where a basic surface is predicted to play a role in binding negatively charged glycosaminoglycans. Our structural and functional characterization of SporoSAG provides a rationale for the evolutionary divergence of this key SRS family member.


  • Organizational Affiliation

    Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8W 3P6, Canada.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
SPOROZOITE-SPECIFIC SAG PROTEIN238Toxoplasma gondii RHMutation(s): 0 
UniProt
Find proteins for Q6RUA7 (Toxoplasma gondii)
Explore Q6RUA7 
Go to UniProtKB:  Q6RUA7
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ6RUA7
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.55 Å
  • R-Value Free: 0.246 
  • R-Value Work: 0.202 
  • R-Value Observed: 0.204 
  • Space Group: P 6
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 106.496α = 90
b = 106.496β = 90
c = 31.616γ = 120
Software Package:
Software NamePurpose
REFMACrefinement
iMOSFLMdata reduction
SCALAdata scaling
autoSHARPphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2010-02-02
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Advisory, Refinement description, Version format compliance
  • Version 1.2: 2019-04-03
    Changes: Data collection, Other, Source and taxonomy