1OQ9

The Crystal Structure of the Complex between Stearoyl Acyl Carrier Protein Desaturase from Ricinus Communis (Castor Bean) and Acetate.


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.40 Å
  • R-Value Free: 0.264 
  • R-Value Work: 0.216 
  • R-Value Observed: 0.218 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

Azide and Acetate Complexes plus two iron-depleted Crystal Structures of the Di-iron Enzyme delta9 Stearoyl-ACP Desaturase-Implications for Oxygen Activation and Catalytic Intermediates

Moche, M.Shanklin, J.Ghoshal, A.Lindqvist, Y.

(2003) J Biol Chem 278: 25072-25080

  • DOI: 10.1074/jbc.M301662200
  • Primary Citation of Related Structures:  
    1OQ9, 1OQ7, 1OQ4, 1OQB

  • PubMed Abstract: 
  • Delta9 stearoyl-acyl carrier protein (ACP) desaturase is a mu-oxo-bridged di-iron enzyme, which belongs to the structural class I of large helix bundle proteins and that catalyzes the NADPH and O2-dependent formation of a cis-double bond in stearoyl- ...

    Delta9 stearoyl-acyl carrier protein (ACP) desaturase is a mu-oxo-bridged di-iron enzyme, which belongs to the structural class I of large helix bundle proteins and that catalyzes the NADPH and O2-dependent formation of a cis-double bond in stearoyl-ACP. The crystal structures of complexes with azide and acetate, respectively, as well as the apoand single-iron forms of Delta9 stearoyl-ACP desaturase from Ricinus communis have been determined. In the azide complex, the ligand forms a mu-1,3-bridge between the two iron ions in the active site, replacing a loosely bound water molecule. The structure of the acetate complex is similar, with acetate bridging the di-iron center in the same orientation with respect to the di-iron center. However, in this complex, the iron ligand Glu196 has changed its coordination mode from bidentate to monodentate, the first crystallographic observation of a carboxylate shift in Delta9 stearoyl-ACP desaturase. The two complexes are proposed to mimic a mu-1,2 peroxo intermediate present during catalytic turnover. There are striking structural similarities between the di-iron center in the Delta9 stearoyl-ACP desaturase-azide complex and in the reduced rubrerythrin-azide complex. This suggests that Delta9 stearoyl-ACP desaturase might catalyze the formation of water from exogenous hydrogen peroxide at a low rate. From the similarity in iron center structure, we propose that the mu-oxo-bridge in oxidized desaturase is bound to the di-iron center as in rubrerythrin and not as reported for the R2 subunit of ribonucleotide reductase and the hydroxylase subunit of methane monooxygenase. The crystal structure of the one-iron depleted desaturase species demonstrates that the affinities for the two iron ions comprising the di-iron center are not equivalent, Fe1 being the higher affinity site and Fe2 being the lower affinity site.


    Organizational Affiliation

    Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm S-171 77, Sweden.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Acyl-[acyl-carrier protein] desaturaseA363Ricinus communisMutation(s): 0 
EC: 1.14.19.2
Find proteins for P22337 (Ricinus communis)
Explore P22337 
Go to UniProtKB:  P22337
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
ACT
Query on ACT

Download CCD File 
A
ACETATE ION
C2 H3 O2
QTBSBXVTEAMEQO-UHFFFAOYSA-M
 Ligand Interaction
FE
Query on FE

Download CCD File 
A
FE (III) ION
Fe
VTLYFUHAOXGGBS-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.40 Å
  • R-Value Free: 0.264 
  • R-Value Work: 0.216 
  • R-Value Observed: 0.218 
  • Space Group: P 31 1 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 94.11α = 90
b = 94.11β = 90
c = 81.783γ = 120
Software Package:
Software NamePurpose
REFMACrefinement
MOSFLMdata reduction
CCP4data scaling
AMoREphasing

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2003-05-13
    Type: Initial release
  • Version 1.1: 2008-04-29
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Advisory, Derived calculations, Refinement description, Version format compliance