1K8C

Crystal structure of dimeric xylose reductase in complex with NADP(H)


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.1 Å
  • R-Value Free: 0.243 
  • R-Value Work: 0.213 

wwPDB Validation 3D Report Full Report


This is version 1.3 of the entry. See complete history

Literature

The structure of apo and holo forms of xylose reductase, a dimeric aldo-keto reductase from Candida tenuis.

Kavanagh, K.L.Klimacek, M.Nidetzky, B.Wilson, D.K.

(2002) Biochemistry 41: 8785-8795

  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Xylose reductase is a homodimeric oxidoreductase dependent on NADPH or NADH and belongs to the largely monomeric aldo-keto reductase superfamily of proteins. It catalyzes the first step in the assimilation of xylose, an aldose found to be a major con ...

    Xylose reductase is a homodimeric oxidoreductase dependent on NADPH or NADH and belongs to the largely monomeric aldo-keto reductase superfamily of proteins. It catalyzes the first step in the assimilation of xylose, an aldose found to be a major constituent monosaccharide of renewable plant hemicellulosic material, into yeast metabolic pathways. It does this by reducing open chain xylose to xylitol, which is reoxidized to xylulose by xylitol dehydrogenase and metabolically integrated via the pentose phosphate pathway. No structure has yet been determined for a xylose reductase, a dimeric aldo-keto reductase or a family 2 aldo-keto reductase. The structures of the Candida tenuis xylose reductase apo- and holoenzyme, which crystallize in spacegroup C2 with different unit cells, have been determined to 2.2 A resolution and an R-factor of 17.9 and 20.8%, respectively. Residues responsible for mediating the novel dimeric interface include Asp-178, Arg-181, Lys-202, Phe-206, Trp-313, and Pro-319. Alignments with other superfamily members indicate that these interactions are conserved in other dimeric xylose reductases but not throughout the remainder of the oligomeric aldo-keto reductases, predicting alternate modes of oligomerization for other families. An arrangement of side chains in a catalytic triad shows that Tyr-52 has a conserved function as a general acid. The loop that folds over the NAD(P)H cosubstrate is disordered in the apo form but becomes ordered upon cosubstrate binding. A slow conformational isomerization of this loop probably accounts for the observed rate-limiting step involving release of cosubstrate. Xylose binding (K(m) = 87 mM) is mediated by interactions with a binding pocket that is more polar than a typical aldo-keto reductase. Modeling of xylose into the active site of the holoenzyme using ordered waters as a guide for sugar hydroxyls suggests a convincing mode of substrate binding.


    Organizational Affiliation

    Section of Molecular and Cellular Biology, University of California-Davis, One Shields Avenue, Davis, CA 95616, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
xylose reductase
A, B, C, D
322Candida tenuisMutation(s): 0 
Gene Names: XYL1 (XYLR)
EC: 1.1.1.307
Find proteins for O74237 (Candida tenuis)
Go to UniProtKB:  O74237
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
NAP
Query on NAP

Download SDF File 
Download CCD File 
A, B, C, D
NADP NICOTINAMIDE-ADENINE-DINUCLEOTIDE PHOSPHATE
2'-MONOPHOSPHOADENOSINE 5'-DIPHOSPHORIBOSE
C21 H28 N7 O17 P3
XJLXINKUBYWONI-NNYOXOHSSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.1 Å
  • R-Value Free: 0.243 
  • R-Value Work: 0.213 
  • Space Group: C 1 2 1
Unit Cell:
Length (Å)Angle (°)
a = 182.202α = 90.00
b = 127.809β = 90.37
c = 80.251γ = 90.00
Software Package:
Software NamePurpose
CNSrefinement
SCALEPACKdata scaling
EPMRphasing
DENZOdata reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2002-07-05
    Type: Initial release
  • Version 1.1: 2008-04-27
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance
  • Version 1.3: 2011-11-16
    Type: Atomic model