Cysteine Synthase from Trypanosoma cruzi with PLP and OAS

Experimental Data Snapshot

  • Resolution: 1.80 Å
  • R-Value Free: 0.217 
  • R-Value Work: 0.191 

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Cysteine synthase: multiple structures of a key enzyme in cysteine synthesis and a potential drug target for Chagas disease and leishmaniasis.

Sowerby, K.Freitag-Pohl, S.Murillo, A.M.Silber, A.M.Pohl, E.

(2023) Acta Crystallogr D Struct Biol 79: 518-530

  • DOI: https://doi.org/10.1107/S2059798323003613
  • Primary Citation of Related Structures:  
    8B9M, 8B9W, 8B9Y

  • PubMed Abstract: 

    Chagas disease is a neglected tropical disease (NTD) caused by Trypanosoma cruzi, whilst leishmaniasis, which is caused by over 20 species of Leishmania, represents a group of NTDs endemic to most countries in the tropical and subtropical belt of the planet. These diseases remain a significant health problem both in endemic countries and globally. These parasites and other trypanosomatids, including T. theileri, a bovine pathogen, rely on cysteine biosynthesis for the production of trypanothione, which is essential for parasite survival in hosts. The de novo pathway of cysteine biosynthesis requires the conversion of O-acetyl-L-serine into L-cysteine, which is catalysed by cysteine synthase (CS). These enzymes present potential for drug development against T. cruzi, Leishmania spp. and T. theileri. To enable these possibilities, biochemical and crystallographic studies of CS from T. cruzi (TcCS), L. infantum (LiCS) and T. theileri (TthCS) were conducted. Crystal structures of the three enzymes were determined at resolutions of 1.80 Å for TcCS, 1.75 Å for LiCS and 2.75 Å for TthCS. These three homodimeric structures show the same overall fold and demonstrate that the active-site geometry is conserved, supporting a common reaction mechanism. Detailed structural analysis revealed reaction intermediates of the de novo pathway ranging from an apo structure of LiCS and holo structures of both TcCS and TthCS to the substrate-bound structure of TcCS. These structures will allow exploration of the active site for the design of novel inhibitors. Additionally, unexpected binding sites discovered at the dimer interface represent new potential for the development of protein-protein inhibitors.

  • Organizational Affiliation

    Department of Parasitology, University of Sao Paulo, São Paulo, Brazil.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Cysteine synthase, putative
A, B, C, D
344Trypanosoma cruziMutation(s): 0 
Gene Names: Tc00.1047053507165.50
Find proteins for Q4CST7 (Trypanosoma cruzi (strain CL Brener))
Explore Q4CST7 
Go to UniProtKB:  Q4CST7
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ4CST7
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 4 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
PLP (Subject of Investigation/LOI)
Query on PLP

Download Ideal Coordinates CCD File 
G [auth A],
H [auth B],
I [auth C],
K [auth D]
C8 H10 N O6 P
Query on RIB

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F [auth A]alpha-D-ribofuranose
C5 H10 O5
OAS (Subject of Investigation/LOI)
Query on OAS

Download Ideal Coordinates CCD File 
C5 H9 N O4
Query on GOL

Download Ideal Coordinates CCD File 
J [auth C],
L [auth D]
C3 H8 O3
Experimental Data & Validation

Experimental Data

  • Resolution: 1.80 Å
  • R-Value Free: 0.217 
  • R-Value Work: 0.191 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 55.006α = 90
b = 66.667β = 90.468
c = 167.518γ = 90
Software Package:
Software NamePurpose
xia2data reduction
xia2data scaling

Structure Validation

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Ligand Structure Quality Assessment 

Entry History & Funding Information

Deposition Data

Funding OrganizationLocationGrant Number
UK Research and Innovation (UKRI)United Kingdom--

Revision History  (Full details and data files)

  • Version 1.0: 2023-05-31
    Type: Initial release
  • Version 1.1: 2023-06-07
    Changes: Database references