4ZU5

Crystal structure of the QdtA 3,4-Ketoisomerase from Thermoanaerobacterium thermosaccharolyticum, apo form


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.80 Å
  • R-Value Free: 0.237 
  • R-Value Work: 0.205 
  • R-Value Observed: 0.206 

Starting Model: experimental
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This is version 1.1 of the entry. See complete history


Literature

Bacterial Sugar 3,4-Ketoisomerases: Structural Insight into Product Stereochemistry.

Thoden, J.B.Vinogradov, E.Gilbert, M.Salinger, A.J.Holden, H.M.

(2015) Biochemistry 54: 4495-4506

  • DOI: https://doi.org/10.1021/acs.biochem.5b00541
  • Primary Citation of Related Structures:  
    4ZU4, 4ZU5, 4ZU7

  • PubMed Abstract: 

    3-Acetamido-3,6-dideoxy-d-galactose (Fuc3NAc) and 3-acetamido-3,6-dideoxy-d-glucose (Qui3NAc) are unusual sugars found on the lipopolysaccharides of Gram-negative bacteria and on the S-layers of Gram-positive bacteria. The 3,4-ketoisomerases, referred to as FdtA and QdtA, catalyze the third steps in the respective biosynthetic pathways for these sugars. Whereas both enzymes utilize the same substrate, the stereochemistries of their products are different. Specifically, the hydroxyl groups at the hexose C-4' positions assume the "galactose" and "glucose" configurations in the FdtA and QdtA products, respectively. In 2007 we reported the structure of the apoform of FdtA from Aneurinibacillus thermoaerophilus, which was followed in 2014 by the X-ray analysis of QdtA from Thermoanaerobacterium thermosaccharolyticum as a binary complex. Both of these enzymes belong to the cupin superfamily. Here we report a combined structural and enzymological study to explore the manner in which these enzymes control the stereochemistry of their products. Various site-directed mutant proteins of each enzyme were constructed, and their dTDP-sugar products were analyzed by NMR spectroscopy. In addition, the kinetic parameters for these protein variants were measured, and the structure of one, namely, the QdtA Y17R/R97H double mutant form, was determined to 2.3-Å resolution. Finally, in an attempt to obtain a model of FdtA with a bound dTDP-linked sugar, the 3,4-ketoisomerase domain of a bifunctional enzyme from Shewanella denitrificans was cloned, purified, and crystallized in the presence of a dTDP-linked sugar analogue. Taken together, the results from this investigation demonstrate that it is possible to convert a "galacto" enzyme into a "gluco" enzyme and vice versa.


  • Organizational Affiliation

    †Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706, United States.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
QdtA
A, B
144Thermoanaerobacterium thermosaccharolyticumMutation(s): 0 
Gene Names: qdtA
UniProt
Find proteins for Q6TFC5 (Thermoanaerobacterium thermosaccharolyticum)
Explore Q6TFC5 
Go to UniProtKB:  Q6TFC5
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ6TFC5
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.80 Å
  • R-Value Free: 0.237 
  • R-Value Work: 0.205 
  • R-Value Observed: 0.206 
  • Space Group: P 4 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 93.742α = 90
b = 93.742β = 90
c = 95.623γ = 90
Software Package:
Software NamePurpose
REFMACrefinement
SAINTdata reduction
SADABSdata scaling
PHASERphasing

Structure Validation

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Ligand Structure Quality Assessment 


Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2016-03-30
    Type: Initial release
  • Version 1.1: 2023-09-27
    Changes: Data collection, Database references, Derived calculations, Refinement description