Crystal Structure of O-Acetylserine Sulfhydrylase from Arabidopsis Thaliana in Complex with C-Terminal Peptide from Arabidopsis Serine Acetyltransferase

Experimental Data Snapshot

  • Resolution: 2.80 Å
  • R-Value Free: 0.248 
  • R-Value Work: 0.188 

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Structural basis for interaction of o-acetylserine sulfhydrylase and serine acetyltransferase in the Arabidopsis cysteine synthase complex.

Francois, J.A.Kumaran, S.Jez, J.M.

(2006) Plant Cell 18: 3647-3655

  • DOI: https://doi.org/10.1105/tpc.106.047316
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    In plants, association of O-acetylserine sulfhydrylase (OASS) and Ser acetyltransferase (SAT) into the Cys synthase complex plays a regulatory role in sulfur assimilation and Cys biosynthesis. We determined the crystal structure of Arabidopsis thaliana OASS (At-OASS) bound with a peptide corresponding to the C-terminal 10 residues of Arabidopsis SAT (C10 peptide) at 2.9-A resolution. Hydrogen bonding interactions with key active site residues (Thr-74, Ser-75, and Gln-147) lock the C10 peptide in the binding site. C10 peptide binding blocks access to OASS catalytic residues, explaining how complex formation downregulates OASS activity. Comparison with bacterial OASS suggests that structural plasticity in the active site allows binding of SAT C termini with dissimilar sequences at structurally similar OASS active sites. Calorimetric analysis of the effect of active site mutations (T74S, S75A, S75T, and Q147A) demonstrates that these residues are important for C10 peptide binding and that changes at these positions disrupt communication between active sites in the homodimeric enzyme. We also demonstrate that the C-terminal Ile of the C10 peptide is required for molecular recognition by At-OASS. These results provide new insights into the molecular mechanism underlying formation of the Cys synthase complex and provide a structural basis for the biochemical regulation of Cys biosynthesis in plants.

  • Organizational Affiliation

    Donald Danforth Plant Science Center, St. Louis, Missouri 63132, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Cysteine synthase320Arabidopsis thalianaMutation(s): 0 
Gene Names: OASA1OAS1OASSOLD3At4g14880dl3480c
Find proteins for P47998 (Arabidopsis thaliana)
Explore P47998 
Go to UniProtKB:  P47998
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP47998
Sequence Annotations
  • Reference Sequence

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Entity ID: 2
MoleculeChains Sequence LengthOrganismDetailsImage
Serine acetyltransferase 18Arabidopsis thalianaMutation(s): 0 
Gene Names: SAT1SAT5At1g55920F14J16.18
Find proteins for Q42588 (Arabidopsis thaliana)
Explore Q42588 
Go to UniProtKB:  Q42588
Entity Groups  
UniProt GroupQ42588
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on PLP

Download Ideal Coordinates CCD File 
C8 H10 N O6 P
Query on SO4

Download Ideal Coordinates CCD File 
O4 S
Experimental Data & Validation

Experimental Data

  • Resolution: 2.80 Å
  • R-Value Free: 0.248 
  • R-Value Work: 0.188 
  • Space Group: P 43 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 104.86α = 90
b = 104.86β = 90
c = 99.315γ = 90
Software Package:
Software NamePurpose
PROTEUM PLUSdata collection
SAINTdata reduction
PROTEUM PLUSdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2007-02-13
    Type: Initial release
  • Version 1.1: 2008-05-01
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Derived calculations, Version format compliance
  • Version 1.3: 2023-08-30
    Changes: Data collection, Database references, Derived calculations, Refinement description