Crystal Structure of GumK mutant D157A

Experimental Data Snapshot

  • Resolution: 2.30 Å
  • R-Value Free: 0.225 
  • R-Value Work: 0.182 
  • R-Value Observed: 0.184 

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Structure and mechanism of GumK, a membrane-associated glucuronosyltransferase.

Barreras, M.Salinas, S.R.Abdian, P.L.Kampel, M.A.Ielpi, L.

(2008) J Biol Chem 283: 25027-25035

  • DOI: https://doi.org/10.1074/jbc.M801227200
  • Primary Citation of Related Structures:  
    2HY7, 2Q6V, 3CUY, 3CV3

  • PubMed Abstract: 

    Xanthomonas campestris GumK (beta-1,2-glucuronosyltransferase) is a 44-kDa membrane-associated protein that is involved in the biosynthesis of xanthan, an exopolysaccharide crucial for this bacterium's phytopathogenicity. Xanthan also has many important industrial applications. The GumK enzyme is the founding member of the glycosyltransferase family 70 of carbohydrate-active enzymes, which is composed of bacterial glycosyltransferases involved in exopolysaccharide synthesis. No x-ray structures have been reported for this family. To better understand the mechanism of action of the bacterial glycosyltransferases in this family, the x-ray crystal structure of apo-GumK was solved at 1.9 angstroms resolution. The enzyme has two well defined Rossmann domains with a catalytic cleft between them, which is a typical feature of the glycosyltransferase B superfamily. Additionally, the crystal structure of GumK complexed with UDP was solved at 2.28 angstroms resolution. We identified a number of catalytically important residues, including Asp157, which serves as the general base in the transfer reaction. Residues Met231, Met273, Glu272, Tyr292, Met306, Lys307, and Gln310 interact with UDP, and mutation of these residues affected protein activity both in vitro and in vivo. The biological and structural data reported here shed light on the molecular basis for donor and acceptor selectivity in this glycosyltransferase family. These results also provide a rationale to obtain new polysaccharides by varying residues in the conserved alpha/beta/alpha structural motif of GumK.

  • Organizational Affiliation

    Laboratory of Bacterial Genetics, Fundación Instituto Leloir, IIBBA-Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires C1405BWE, Argentina.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Glucuronosyltransferase GumK406Xanthomonas campestris pv. campestrisMutation(s): 1 
Gene Names: gumK
Find proteins for Q8GCH2 (Xanthomonas campestris pv. campestris)
Explore Q8GCH2 
Go to UniProtKB:  Q8GCH2
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ8GCH2
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.30 Å
  • R-Value Free: 0.225 
  • R-Value Work: 0.182 
  • R-Value Observed: 0.184 
  • Space Group: P 65 2 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 121.726α = 90
b = 121.726β = 90
c = 172.557γ = 120
Software Package:
Software NamePurpose
SCALAdata scaling
PDB_EXTRACTdata extraction
MAR345dtbdata collection
MOSFLMdata reduction
ARP/wARPmodel building

Structure Validation

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Entry History 

Deposition Data

  • Released Date: 2008-07-01 
  • Deposition Author(s): Barreras, M.

Revision History  (Full details and data files)

  • Version 1.0: 2008-07-01
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2021-10-20
    Changes: Database references, Source and taxonomy
  • Version 1.3: 2023-08-30
    Changes: Data collection, Refinement description