2PQM

Crystal structure of Cysteine Synthase (OASS) from Entamoeba histolytica at 1.86 A resolution


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.86 Å
  • R-Value Free: 0.211 
  • R-Value Work: 0.180 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Crystal structure of native O-acetyl-serine sulfhydrylase from Entamoeba histolytica and its complex with cysteine: structural evidence for cysteine binding and lack of interactions with serine acetyl transferase.

Chinthalapudi, K.Kumar, M.Kumar, S.Jain, S.Alam, N.Gourinath, S.

(2008) Proteins 72: 1222-1232

  • DOI: 10.1002/prot.22013
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Cysteine plays a major role in the antioxidative defense mechanisms of the human parasite Entameoba histolytica. The major route of cysteine biosynthesis in this parasite is the condensation of O-acetylserine with sulfide by the de novo cysteine bios ...

    Cysteine plays a major role in the antioxidative defense mechanisms of the human parasite Entameoba histolytica. The major route of cysteine biosynthesis in this parasite is the condensation of O-acetylserine with sulfide by the de novo cysteine biosynthetic pathway involving two key enzymes O-acetyl-L-serine sulfhydrylase (OASS) and serine acetyl transferase (SAT). The crystal structure of native OASS from Entameoba histolytica (EhOASS) has been determined at 1.86 A resolution and in complex with its product cysteine at 2.4 A resolution. In comparison with other known OASS structures, insertion in the N-terminal region and C-terminal helix reveal critical differences, which may influence the protein-protein interactions. In spite of lacking chloride binding site at the dimeric interface, the N-terminal extension compared with other known cysteine synthases, participates in dimeric interactions in an interesting domain swapping manner, enabling it to form a stronger dimer. Sulfate is bound in the active site of the native structure, which is replaced by cysteine in the cysteine bound form causing reorientation of the small N-terminal domain and thus closure of the active site. Ligand binding constants of OAS, Cys, and Met with EhOASS are comparable with other known OASS indicating similar active site arrangement and dynamics. The cysteine complexed structure represents the snapshot of the enzyme just before releasing the final product with a closed active site. The C-terminal helix positioning in the EhOASS may effect its interactions with EhSAT and thus influencing the formation of the cysteine synthase complex in this organism.


    Organizational Affiliation

    School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Cysteine synthase
A, B
343Entamoeba histolyticaMutation(s): 0 
Find proteins for O15570 (Entamoeba histolytica)
Go to UniProtKB:  O15570
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
SO4
Query on SO4

Download SDF File 
Download CCD File 
A, B
SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
 Ligand Interaction
PLP
Query on PLP

Download SDF File 
Download CCD File 
A, B
PYRIDOXAL-5'-PHOSPHATE
VITAMIN B6 Phosphate
C8 H10 N O6 P
NGVDGCNFYWLIFO-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.86 Å
  • R-Value Free: 0.211 
  • R-Value Work: 0.180 
  • Space Group: P 41
Unit Cell:
Length (Å)Angle (°)
a = 80.316α = 90.00
b = 80.316β = 90.00
c = 112.224γ = 90.00
Software Package:
Software NamePurpose
MOLREPphasing
REFMACrefinement
PDB_EXTRACTdata extraction
HKL-2000data collection
HKL-2000data reduction
HKL-2000data scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2008-04-15
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Source and taxonomy, Version format compliance