1Z7W

Crystal Structure of O-Acetylserine Sulfhydrylase from Arabidopsis thaliana


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.20 Å
  • R-Value Free: 0.209 
  • R-Value Work: 0.186 

Starting Model: experimental
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This is version 1.3 of the entry. See complete history


Literature

Molecular Basis of Cysteine Biosynthesis in Plants: STRUCTURAL AND FUNCTIONAL ANALYSIS OF O-ACETYLSERINE SULFHYDRYLASE FROM ARABIDOPSIS THALIANA.

Bonner, E.R.Cahoon, R.E.Knapke, S.M.Jez, J.M.

(2005) J Biol Chem 280: 38803-38813

  • DOI: https://doi.org/10.1074/jbc.M505313200
  • Primary Citation of Related Structures:  
    1Z7W, 1Z7Y

  • PubMed Abstract: 

    In plants, cysteine biosynthesis plays a central role in fixing inorganic sulfur from the environment and provides the only metabolic sulfide donor for the generation of methionine, glutathione, phytochelatins, iron-sulfur clusters, vitamin cofactors, and multiple secondary metabolites. O-Acetylserine sulfhydrylase (OASS) catalyzes the final step of cysteine biosynthesis, the pyridoxal 5'-phosphate (PLP)-dependent conversion of O-acetylserine into cysteine. Here we describe the 2.2 A resolution crystal structure of OASS from Arabidopsis thaliana (AtOASS) and the 2.7 A resolution structure of the AtOASS K46A mutant with PLP and methionine covalently linked as an external aldimine in the active site. Although the plant and bacterial OASS share a conserved set of amino acids for PLP binding, the structure of AtOASS reveals a difference from the bacterial enzyme in the positioning of an active site loop formed by residues 74-78 when methionine is bound. Site-directed mutagenesis, kinetic analysis, and ligand binding titrations probed the functional roles of active site residues. These experiments indicate that Asn(77) and Gln(147) are key amino acids for O-acetylserine binding and that Thr(74) and Ser(75) are involved in sulfur incorporation into cysteine. In addition, examination of the AtOASS structure and nearly 300 plant and bacterial OASS sequences suggest that the highly conserved beta8A-beta9A surface loop may be important for interaction with serine acetyltransferase, the other enzyme in cysteine biosynthesis. Initial protein-protein interaction experiments using AtOASS mutants targeted to this loop support this hypothesis.


  • Organizational Affiliation

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


Macromolecules
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Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Cysteine synthase322Arabidopsis thalianaMutation(s): 0 
Gene Names: OASA1OAS1
EC: 2.5.1.47
UniProt
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
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.20 Å
  • R-Value Free: 0.209 
  • R-Value Work: 0.186 
  • Space Group: P 43 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 105.153α = 90
b = 105.153β = 90
c = 100.133γ = 90
Software Package:
Software NamePurpose
PROTEUM PLUSdata collection
PROTEUM PLUSdata reduction
CNSrefinement
PROTEUM PLUSdata scaling
CNSphasing

Structure Validation

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Ligand Structure Quality Assessment 


Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2005-09-20
    Type: Initial release
  • Version 1.1: 2008-04-29
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Derived calculations, Version format compliance
  • Version 1.3: 2023-08-23
    Changes: Data collection, Database references, Derived calculations, Refinement description