Crystal Structure Of An Engineered K274RN276D Double Mutant of Xylose Reductase From Candida Tenuis Optimized To Utilize NAD

Experimental Data Snapshot

  • Resolution: 2.20 Å
  • R-Value Free: 0.240 
  • R-Value Work: 0.194 
  • R-Value Observed: 0.194 

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This is version 1.6 of the entry. See complete history


The coenzyme specificity of Candida tenuis xylose reductase (AKR2B5) explored by site-directed mutagenesis and X-ray crystallography.

Petschacher, B.Leitgeb, S.Kavanagh, K.L.Wilson, D.K.Nidetzky, B.

(2005) Biochem J 385: 75-83

  • DOI: https://doi.org/10.1042/BJ20040363
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    CtXR (xylose reductase from the yeast Candida tenuis; AKR2B5) can utilize NADPH or NADH as co-substrate for the reduction of D-xylose into xylitol, NADPH being preferred approx. 33-fold. X-ray structures of CtXR bound to NADP+ and NAD+ have revealed two different protein conformations capable of accommodating the presence or absence of the coenzyme 2'-phosphate group. Here we have used site-directed mutagenesis to replace interactions specific to the enzyme-NADP+ complex with the aim of engineering the co-substrate-dependent conformational switch towards improved NADH selectivity. Purified single-site mutants K274R (Lys274-->Arg), K274M, K274G, S275A, N276D, R280H and the double mutant K274R-N276D were characterized by steady-state kinetic analysis of enzymic D-xylose reductions with NADH and NADPH at 25 degrees C (pH 7.0). The results reveal between 2- and 193-fold increases in NADH versus NADPH selectivity in the mutants, compared with the wild-type, with only modest alterations of the original NADH-linked xylose specificity and catalytic-centre activity. Catalytic reaction profile analysis demonstrated that all mutations produced parallel effects of similar magnitude on ground-state binding of coenzyme and transition state stabilization. The crystal structure of the double mutant showing the best improvement of coenzyme selectivity versus wild-type and exhibiting a 5-fold preference for NADH over NADPH was determined in a binary complex with NAD+ at 2.2 A resolution.

  • Organizational Affiliation

    Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, Petersgasse 12/I, A-8010 Graz, Austria.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
xylose reductase
A, B, C, D
322Yamadazyma tenuisMutation(s): 2 
Find proteins for O74237 (Candida tenuis)
Explore O74237 
Go to UniProtKB:  O74237
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupO74237
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.20 Å
  • R-Value Free: 0.240 
  • R-Value Work: 0.194 
  • R-Value Observed: 0.194 
  • Space Group: C 1 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 180.74α = 90
b = 128.19β = 90.43
c = 79.67γ = 90
Software Package:
Software NamePurpose
SCALEPACKdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2004-12-21
    Type: Initial release
  • Version 1.1: 2008-04-29
    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: 2017-10-11
    Changes: Refinement description
  • Version 1.5: 2021-10-27
    Changes: Database references, Derived calculations
  • Version 1.6: 2023-08-23
    Changes: Data collection, Refinement description