Apo form of threonine synthase from Thermus thermophilus HB8

Experimental Data Snapshot

  • Resolution: 1.92 Å
  • R-Value Free: 0.214 
  • R-Value Work: 0.190 
  • R-Value Observed: 0.190 

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Product-assisted catalysis as the basis of the reaction specificity of threonine synthase.

Murakawa, T.Machida, Y.Hayashi, H.

(2011) J Biol Chem 286: 2774-2784

  • DOI: https://doi.org/10.1074/jbc.M110.186205
  • Primary Citation of Related Structures:  
    3AEX, 3AEY

  • PubMed Abstract: 

    Threonine synthase (TS), which is a pyridoxal 5'-phosphate (PLP)-dependent enzyme, catalyzes the elimination of the γ-phosphate group from O-phospho-L-homoserine (OPHS) and the subsequent addition of water at Cβ to form L-threonine. The catalytic course of TS is the most complex among the PLP enzymes, and it is an intriguing problem how the elementary steps are controlled in TS to carry out selective reactions. When L-vinylglycine was added to Thermus thermophilus HB8 TS in the presence of phosphate, L-threonine was formed with k(cat) and reaction specificity comparable with those when OPHS was used as the substrate. However, in the absence of phosphate or when sulfate was used in place of phosphate, only the side reaction product, α-ketobutyrate, was formed. Global analysis of the spectral changes in the reaction of TS with L-threonine showed that compared with the more acidic sulfate ion, the phosphate ion decreased the energy levels of the transition states of the addition of water at the Cβ of the PLP-α-aminocrotonate aldimine (AC) and the transaldimination to form L-threonine. The x-ray crystallographic analysis of TS complexed with an analog for AC gave a distinct electron density assigned to the phosphate ion derived from the solvent near the Cβ of the analog. These results indicated that the phosphate ion released from OPHS by γ-elimination acts as the base catalyst for the addition of water at Cβ of AC, thereby providing the basis of the reaction specificity. The phosphate ion is also considered to accelerate the protonation/deprotonation at Cγ.

  • Organizational Affiliation

    Department of Biochemistry, Faculty of Medicine, Osaka Medical College, Takatsuki 569-8686, Japan.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Threonine synthase
A, B
351Thermus thermophilus HB8Mutation(s): 0 
Gene Names: TTHA0491
Find proteins for Q5SL02 (Thermus thermophilus (strain ATCC 27634 / DSM 579 / HB8))
Explore Q5SL02 
Go to UniProtKB:  Q5SL02
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ5SL02
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.92 Å
  • R-Value Free: 0.214 
  • R-Value Work: 0.190 
  • R-Value Observed: 0.190 
  • Space Group: P 32 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 112.969α = 90
b = 112.969β = 90
c = 150.262γ = 120
Software Package:
Software NamePurpose
DNAdata collection
HKL-2000data reduction
HKL-2000data scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2010-11-17
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2023-11-01
    Changes: Data collection, Database references, Derived calculations, Refinement description