Entropic stabilization of the tryptophan synthase A-subunit from a hyperthermophile, pyrococcus furiosus: X-ray analysis and calorimetry

Experimental Data Snapshot

  • Resolution: 2.00 Å
  • R-Value Free: 0.249 
  • R-Value Work: 0.198 

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Entropic stabilization of the tryptophan synthase alpha-subunit from a hyperthermophile, Pyrococcus furiosus. X-ray analysis and calorimetry.

Yamagata, Y.Ogasahara, K.Hioki, Y.Lee, S.J.Nakagawa, A.Nakamura, H.Ishida, M.Kuramitsu, S.Yutani, K.

(2001) J Biol Chem 276: 11062-11071

  • DOI: https://doi.org/10.1074/jbc.M009987200
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    The structure of the tryptophan synthase alpha-subunit from Pyrococcus furiosus was determined by x-ray analysis at 2.0-A resolution, and its stability was examined by differential scanning calorimetry. Although the structure of the tryptophan synthase alpha(2)beta(2) complex from Salmonella typhimurium has been already determined, this is the first report of the structure of the alpha-subunit alone. The alpha-subunit from P. furiosus (Pf-alpha-subunit) lacked 12 and 6 residues at the N and C termini, respectively, and one residue each in two loop regions as compared with that from S. typhimurium (St-alpha-subunit), resulting in the absence of an N-terminal helix and the shortening of a C-terminal helix. The structure of the Pf-alpha-subunit was essentially similar to that of the St-alpha-subunit in the alpha(2)beta(2) complex. The differences between both structures were discussed in connection with the higher stability of the Pf-alpha-subunit and the complex formation of the alpha- and beta-subunits. Calorimetric results indicated that the Pf-alpha-subunit has extremely high thermostability and that its higher stability is caused by an entropic effect. On the basis of structural information of both proteins, we analyzed the contributions of each stabilization factor and could conclude that hydrophobic interactions in the protein interior do not contribute to the higher stability of the Pf-alpha-subunit. Rather, the increase in ion pairs, decrease in cavity volume, and entropic effects due to shortening of the polypeptide chain play important roles in extremely high stability in Pf-alpha-subunit.

  • Organizational Affiliation

    Graduate School of Pharmaceutical Sciences, and Institute for Protein Research, Osaka University, Yamadaoka, Suita, Osaka 565-0871, Japan.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
A, B
248Pyrococcus furiosusMutation(s): 0 
Find proteins for Q8U094 (Pyrococcus furiosus (strain ATCC 43587 / DSM 3638 / JCM 8422 / Vc1))
Explore Q8U094 
Go to UniProtKB:  Q8U094
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ8U094
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.00 Å
  • R-Value Free: 0.249 
  • R-Value Work: 0.198 
  • Space Group: C 2 2 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 73.013α = 90
b = 78.997β = 90
c = 170.964γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2000-12-13
    Type: Initial release
  • Version 1.1: 2008-04-24
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2011-11-16
    Changes: Atomic model
  • Version 1.4: 2023-12-27
    Changes: Data collection, Database references