3OPZ

Crystal structure of trans-sialidase in complex with the Fab fragment of a neutralizing monoclonal IgG antibody


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.4 Å
  • R-Value Free: 0.205 
  • R-Value Work: 0.164 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Trypanosoma cruzi trans-sialidase in complex with a neutralizing antibody: structure/function studies towards the rational design of inhibitors.

Buschiazzo, A.Muia, R.Larrieux, N.Pitcovsky, T.Mucci, J.Campetella, O.

(2012) Plos Pathog. 8: e1002474-e1002474

  • DOI: 10.1371/journal.ppat.1002474

  • PubMed Abstract: 
  • Trans-sialidase (TS), a virulence factor from Trypanosoma cruzi, is an enzyme playing key roles in the biology of this protozoan parasite. Absent from the mammalian host, it constitutes a potential target for the development of novel chemotherapeutic ...

    Trans-sialidase (TS), a virulence factor from Trypanosoma cruzi, is an enzyme playing key roles in the biology of this protozoan parasite. Absent from the mammalian host, it constitutes a potential target for the development of novel chemotherapeutic drugs, an urgent need to combat Chagas' disease. TS is involved in host cell invasion and parasite survival in the bloodstream. However, TS is also actively shed by the parasite to the bloodstream, inducing systemic effects readily detected during the acute phase of the disease, in particular, hematological alterations and triggering of immune cells apoptosis, until specific neutralizing antibodies are elicited. These antibodies constitute the only known submicromolar inhibitor of TS's catalytic activity. We now report the identification and detailed characterization of a neutralizing mouse monoclonal antibody (mAb 13G9), recognizing T. cruzi TS with high specificity and subnanomolar affinity. This mAb displays undetectable association with the T. cruzi superfamily of TS-like proteins or yet with the TS-related enzymes from Trypanosoma brucei or Trypanosoma rangeli. In immunofluorescence assays, mAb 13G9 labeled 100% of the parasites from the infective trypomastigote stage. This mAb also reduces parasite invasion of cultured cells and strongly inhibits parasite surface sialylation. The crystal structure of the mAb 13G9 antigen-binding fragment in complex with the globular region of T. cruzi TS was determined, revealing detailed molecular insights of the inhibition mechanism. Not occluding the enzyme's catalytic site, the antibody performs a subtle action by inhibiting the movement of an assisting tyrosine (Y₁₁₉), whose mobility is known to play a key role in the trans-glycosidase mechanism. As an example of enzymatic inhibition involving non-catalytic residues that occupy sites distal from the substrate-binding pocket, this first near atomic characterization of a high affinity inhibitory molecule for TS provides a rational framework for novel strategies in the design of chemotherapeutic compounds.


    Organizational Affiliation

    Institut Pasteur de Montevideo, Unit of Protein Crystallography, Montevideo, Uruguay. alebus@pasteur.edu.uy




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Trans-sialidase
A, B, C
648Trypanosoma cruziMutation(s): 11 
Find proteins for Q26966 (Trypanosoma cruzi)
Go to UniProtKB:  Q26966
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
heavy chain of the Fab fragment of immunoglobulin G
H, I, J
222N/AMutation(s): 0 
Protein Feature View is not available: No corresponding UniProt sequence found.
Entity ID: 3
MoleculeChainsSequence LengthOrganismDetails
light chain of the Fab fragment of immunoglobulin G
L, M, N
213N/AMutation(s): 0 
Protein Feature View is not available: No corresponding UniProt sequence found.
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
NA
Query on NA

Download SDF File 
Download CCD File 
A
SODIUM ION
Na
FKNQFGJONOIPTF-UHFFFAOYSA-N
 Ligand Interaction
DIO
Query on DIO

Download SDF File 
Download CCD File 
A, B
1,4-DIETHYLENE DIOXIDE
C4 H8 O2
RYHBNJHYFVUHQT-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.4 Å
  • R-Value Free: 0.205 
  • R-Value Work: 0.164 
  • Space Group: P 31
Unit Cell:
Length (Å)Angle (°)
a = 178.140α = 90.00
b = 178.140β = 90.00
c = 140.710γ = 120.00
Software Package:
Software NamePurpose
MAR345dtbdata collection
MOSFLMdata reduction
PDB_EXTRACTdata extraction
SCALAdata scaling
REFMACrefinement
PHASERphasing

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2011-11-09
    Type: Initial release
  • Version 1.1: 2012-03-07
    Type: Database references