1N1T

Trypanosoma rangeli sialidase in complex with DANA at 1.6 A


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.60 Å
  • R-Value Free: 0.197 
  • R-Value Work: 0.173 
  • R-Value Observed: 0.174 

wwPDB Validation   3D Report Full Report


This is version 1.3 of the entry. See complete history


Literature

The high resolution structures of free and inhibitor-bound Trypanosoma rangeli sialidase and its comparison with T. cruzi trans-sialidase

Amaya, M.F.Buschiazzo, A.Nguyen, T.Alzari, P.M.

(2003) J Mol Biol 325: 773-784

  • DOI: https://doi.org/10.1016/s0022-2836(02)01306-2
  • Primary Citation of Related Structures:  
    1N1S, 1N1T, 1N1V, 1N1Y

  • PubMed Abstract: 

    The structure of the recombinant Trypanosoma rangeli sialidase (TrSA) has been determined at 1.6A resolution, and the structures of its complexes with the transition state analog inhibitor 2-deoxy-2,3-dehydro-N-acetyl-neuraminic acid (DANA), Neu-5-Ac-thio-alpha(2,3)-galactoside (NATG) and N-acetylneuraminic acid (NANA) have been determined at 1.64A, 2.1A and 2.85A, respectively. The 3D structure of TrSA is essentially identical to that of the natural enzyme, except for the absence of covalently attached sugar at five distinct N-glycosylation sites. The protein exhibits a topologically rigid active site architecture that is unaffected by ligand binding. The overall binding of DANA to the active site cleft is similar to that observed for other viral and bacterial sialidases, dominated by the interactions of the inhibitor carboxylate with the conserved arginine triad. However, the interactions of the other pyranoside ring substituents (hydroxyl, N-acetyl and glycerol moieties) differ between trypanosomal, bacterial and viral sialidases, providing a structural basis for specific inhibitor design. Sialic acid is found to bind the enzyme with the sugar ring in a distorted (half-chair or boat) conformation and the 2-OH hydroxyl group at hydrogen bonding distance of the carboxylate of Asp60, substantiating a direct catalytic role for this residue. A detailed comparison of TrSA with the closely related structure of T.cruzi trans-sialidase (TcTS) reveals a highly conserved catalytic center, where subtle structural differences account for strikingly different enzymatic activities and inhibition properties. The structure of TrSA in complex with NATG shows the active site cleft occupied by a smaller compound which could be identified as DANA, probably the product of a hydrolytic side reaction. Indeed, TrSA (but not TcTS) was found to cleave O and S-linked sialylated substrates, further stressing the functional differences between trypanosomal sialidases and trans-sialidases.


  • Organizational Affiliation

    Unité de Biochimie Structurale, CNRS URA 2185, Institut Pasteur, 25 rue du Dr. Roux, 75724 Paris cédex 15, France.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Sialidase641Trypanosoma rangeliMutation(s): 0 
EC: 3.2.1.18
UniProt
Find proteins for O44049 (Trypanosoma rangeli)
Explore O44049 
Go to UniProtKB:  O44049
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupO44049
Sequence Annotations
Expand
  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
DAN
Query on DAN

Download Ideal Coordinates CCD File 
D [auth A]2-DEOXY-2,3-DEHYDRO-N-ACETYL-NEURAMINIC ACID
C11 H17 N O8
JINJZWSZQKHCIP-UFGQHTETSA-N
SO4
Query on SO4

Download Ideal Coordinates CCD File 
B [auth A],
C [auth A]
SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
Binding Affinity Annotations 
IDSourceBinding Affinity
DAN PDBBind:  1N1T Ki: 1.40e+5 (nM) from 1 assay(s)
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.60 Å
  • R-Value Free: 0.197 
  • R-Value Work: 0.173 
  • R-Value Observed: 0.174 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 73.945α = 90
b = 96.258β = 90
c = 106.513γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling
AMoREphasing
REFMACrefinement

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2003-01-07
    Type: Initial release
  • Version 1.1: 2008-04-28
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2020-07-29
    Type: Remediation
    Reason: Carbohydrate remediation
    Changes: Data collection, Database references, Derived calculations