1MMZ

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


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.80 Å
  • R-Value Free: 0.230 
  • R-Value Work: 0.169 
  • R-Value Observed: 0.172 

Starting Model: experimental
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This is version 1.6 of the entry. See complete history


Literature

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


Macromolecules
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
EC: 5.1.3.3
UniProt
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
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • 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
TNTrefinement
SAINTdata scaling
TNTphasing

Structure Validation

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Ligand Structure Quality Assessment 


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
  • Version 1.6: 2024-02-14
    Changes: Data collection, Refinement description