2NNR

Crystal structure of chagasin, cysteine protease inhibitor from Trypanosoma cruzi


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.7 Å
  • R-Value Free: 0.216 
  • R-Value Work: 0.186 

wwPDB Validation 3D Report Full Report


This is version 1.3 of the entry. See complete history

Literature

Crystal structure of the parasite protease inhibitor chagasin in complex with a host target cysteine protease

Ljunggren, A.Redzynia, I.Alvarez-Fernandez, M.Abrahamson, M.Mort, J.S.Krupa, J.C.Jaskolski, M.Bujacz, G.

(2007) J.Mol.Biol. 371: 137-153

  • DOI: 10.1016/j.jmb.2007.05.005
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Chagasin is a protein produced by Trypanosoma cruzi, the parasite that causes Chagas' disease. This small protein belongs to a recently defined family of cysteine protease inhibitors. Although resembling well-known inhibitors like the cystatins in si ...

    Chagasin is a protein produced by Trypanosoma cruzi, the parasite that causes Chagas' disease. This small protein belongs to a recently defined family of cysteine protease inhibitors. Although resembling well-known inhibitors like the cystatins in size (110 amino acid residues) and function (they all inhibit papain-like (C1 family) proteases), it has a unique amino acid sequence and structure. We have crystallized and solved the structure of chagasin in complex with the host cysteine protease, cathepsin L, at 1.75 A resolution. An inhibitory wedge composed of three loops (L2, L4, and L6) forms a number of contacts responsible for high-affinity binding (K(i), 39 pM) to the enzyme. All three loops interact with the catalytic groove, with the central loop L2 inserted directly into the catalytic center. Loops L4 and L6 embrace the enzyme molecule from both sides and exhibit distinctly different patterns of protein-protein recognition. Comparison with a 1.7 A structure of uncomplexed chagasin, also determined in this study, demonstrates that a conformational change of the first binding loop (L4) allows extended binding to the non-primed substrate pockets of the enzyme active site cleft, thereby providing a substantial part of the inhibitory surface. The mode of chagasin binding is generally similar, albeit distinctly different in detail, when compared to those displayed by cystatins and the cysteine protease inhibitory p41 fragment of the invariant chain. The chagasin-cathepsin L complex structure provides details of how the parasite protein inhibits a host enzyme of possible importance in host defense. The high level of structural and functional similarity between cathepsin L and the T. cruzi enzyme cruzipain gives clues to how the cysteine protease activity of the parasite can be targeted. This information will aid in the development of synthetic inhibitors for use as potential drugs for the treatment of Chagas disease.


    Organizational Affiliation

    Department of Laboratory Medicine, Division of Clinical Chemistry and Pharmacology, Lund University, University Hospital, SE-221 85 Lund, Sweden.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Chagasin
A, B
110Trypanosoma cruziMutation(s): 0 
Gene Names: cha
Find proteins for Q966X9 (Trypanosoma cruzi)
Go to UniProtKB:  Q966X9
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
SO4
Query on SO4

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Download CCD File 
A
SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
 Ligand Interaction
CL
Query on CL

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Download CCD File 
B
CHLORIDE ION
Cl
VEXZGXHMUGYJMC-UHFFFAOYSA-M
 Ligand Interaction
GOL
Query on GOL

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Download CCD File 
A, B
GLYCEROL
GLYCERIN; PROPANE-1,2,3-TRIOL
C3 H8 O3
PEDCQBHIVMGVHV-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.7 Å
  • R-Value Free: 0.216 
  • R-Value Work: 0.186 
  • Space Group: P 31 1 2
Unit Cell:
Length (Å)Angle (°)
a = 49.546α = 90.00
b = 49.546β = 90.00
c = 187.576γ = 120.00
Software Package:
Software NamePurpose
SCALEPACKdata scaling
PDB_EXTRACTdata extraction
HKL-2000data collection
REFMACrefinement
Auto-Rickshawphasing
DENZOdata reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2007-07-24
    Type: Initial release
  • Version 1.1: 2008-05-01
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Advisory, Version format compliance
  • Version 1.3: 2017-10-18
    Type: Refinement description