Crystal structure of galactose mutarotase from Lactococcus lactis complexed with L-arabinose

Experimental Data Snapshot

  • Resolution: 1.80 Å
  • R-Value Free: 0.230 
  • R-Value Work: 0.169 
  • R-Value Observed: 0.172 

wwPDB Validation   3D Report Full Report

This is version 1.5 of the entry. See complete history


Structural and kinetic studies of sugar binding to galactose mutarotase from Lactococcus lactis.

Thoden, J.B.Kim, J.Raushel, F.M.Holden, H.M.

(2002) J Biol Chem 277: 45458-45465

  • DOI: https://doi.org/10.1074/jbc.M208395200
  • Primary Citation of Related Structures:  
    1MMU, 1MMX, 1MMY, 1MMZ, 1MN0

  • PubMed Abstract: 

    Galactose mutarotase catalyzes the conversion of beta-D-galactose to alpha-D-galactose in the Leloir pathway for galactose metabolism. The high resolution x-ray structure of the dimeric enzyme from Lactococcus lactis was recently solved and shown to be topologically similar to the 18-stranded, anti-parallel beta-motif observed for domain 5 of beta-galactosidase. In addition to determining the overall molecular fold of galactose mutarotase, this initial investigation also provided a detailed description of the electrostatic interactions between the enzyme and its physiologically relevant substrate, galactose. Specifically, the side chains of His-96 and His-170 were shown to be located within hydrogen bonding distance to the C-5 oxygen of the substrate, while the carboxylate of Glu-304 was positioned near the C-1 hydroxyl group of the sugar. On the basis of this initial study, a possible role for Glu-304 as the general acid/base group in catalysis was put forth. Here we describe the combined x-ray crystallographic and kinetic analyses of L. lactis galactose mutarotase complexed with D-glucose, D-fucose, D-quinovose, L-arabinose, or D-xylose. These investigations have revealed that there are several distinct binding modes for these sugars, which are dependent upon the spatial orientation of the C-4 hydroxyl group. In those sugars with the same C-4 hydroxyl group orientation as galactose, their C-1 hydroxyl groups are invariably located near Glu-304. For those sugars, which have the same C-4 hydroxyl group configuration as glucose, the C-1 hydroxyls are typically located near Asp-243. These different binding modes correlate with both the observed kinetic parameters and the presence or absence of a hydrogen bond between the guanidinium group of Arg-71 and the C-4 hydroxyl group of the sugar ligand.

  • Organizational Affiliation

    Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706-1544, USA. JBThoden@facstaff.wisc.edu

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Aldose 1-epimerase
A, B
347Lactococcus lactisMutation(s): 1 
Gene Names: galM
Find proteins for Q9ZB17 (Lactococcus lactis)
Explore Q9ZB17 
Go to UniProtKB:  Q9ZB17
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ9ZB17
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.80 Å
  • R-Value Free: 0.230 
  • R-Value Work: 0.169 
  • R-Value Observed: 0.172 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 44.9α = 90
b = 76.3β = 90
c = 210.9γ = 90
Software Package:
Software NamePurpose
FRAMBOdata collection
SAINTdata reduction
SAINTdata scaling

Structure Validation

View Full Validation Report

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2002-09-18
    Type: Initial release
  • Version 1.1: 2008-04-28
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2017-10-11
    Changes: Refinement description
  • Version 1.4: 2020-07-29
    Type: Remediation
    Reason: Carbohydrate remediation
    Changes: Advisory, Data collection, Database references, Derived calculations, Structure summary
  • Version 1.5: 2021-10-27
    Changes: Database references, Structure summary