Experimental Data Snapshot

  • Resolution: 1.71 Å
  • R-Value Free: 0.245 
  • R-Value Work: 0.186 
  • R-Value Observed: 0.186 

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Mechanism of 8-amino-7-oxononanoate synthase: spectroscopic, kinetic, and crystallographic studies.

Webster, S.P.Alexeev, D.Campopiano, D.J.Watt, R.M.Alexeeva, M.Sawyer, L.Baxter, R.L.

(2000) Biochemistry 39: 516-528

  • DOI: https://doi.org/10.1021/bi991620j
  • Primary Citation of Related Structures:  
    1DJ9, 1DJE

  • PubMed Abstract: 

    8-Amino-7-oxononanoate synthase (also known as 7-keto-8-aminopelargonate synthase, EC is a pyridoxal 5'-phosphate-dependent enzyme which catalyzes the decarboxylative condensation of L-alanine with pimeloyl-CoA in a stereospecific manner to form 8(S)-amino-7-oxononanoate. This is the first committed step in biotin biosynthesis. The mechanism of Escherichia coli AONS has been investigated by spectroscopic, kinetic, and crystallographic techniques. The X-ray structure of the holoenzyme has been refined at a resolution of 1.7 A (R = 18.6%, R(free) = 21. 2%) and shows that the plane of the imine bond of the internal aldimine deviates from the pyridine plane. The structure of the enzyme-product external aldimine complex has been refined at a resolution of 2.0 A (R = 21.2%, R(free) = 27.8%) and shows a rotation of the pyridine ring with respect to that in the internal aldimine, together with a significant conformational change of the C-terminal domain and subtle rearrangement of the active site hydrogen bonding. The first step in the reaction, L-alanine external aldimine formation, is rapid (k(1) = 2 x 10(4) M(-)(1) s(-)(1)). Formation of an external aldimine with D-alanine, which is not a substrate, is significantly slower (k(1) = 125 M(-)(1) s(-)(1)). Binding of D-alanine to AONS is enhanced approximately 2-fold in the presence of pimeloyl-CoA. Significant substrate quinonoid formation only occurs upon addition of pimeloyl-CoA to the preformed L-alanine external aldimine complex and is preceded by a distinct lag phase ( approximately 30 ms) which suggests that binding of the pimeloyl-CoA causes a conformational transition of the enzyme external aldimine complex. This transition, which is inferred by modeling to require a rotation around the Calpha-N bond of the external aldimine complex, promotes abstraction of the Calpha proton by Lys236. These results have been combined to form a detailed mechanistic pathway for AONS catalysis which may be applied to the other members of the alpha-oxoamine synthase subfamily.

  • Organizational Affiliation

    Edinburgh Centre for Protein Technology, Department of Chemistry, University of Edinburgh, King's Buildings, Edinburgh EH9 3JJ, United Kingdom.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
8-AMINO-7-OXONANOATE SYNTHASE384Escherichia coliMutation(s): 0 
Find proteins for P12998 (Escherichia coli (strain K12))
Explore P12998 
Go to UniProtKB:  P12998
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP12998
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.71 Å
  • R-Value Free: 0.245 
  • R-Value Work: 0.186 
  • R-Value Observed: 0.186 
  • Space Group: P 31 1 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 58.87α = 90
b = 58.87β = 90
c = 200.8γ = 120
Software Package:
Software NamePurpose
X-PLORmodel building
MAR345data collection
SCALEPACKdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2000-12-04
    Type: Initial release
  • Version 1.1: 2008-04-27
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Derived calculations, Version format compliance
  • Version 1.3: 2017-10-04
    Changes: Refinement description
  • Version 1.4: 2018-01-24
    Changes: Database references