Crystal structure PseG-UDP complex from Campylobacter jejuni

Experimental Data Snapshot

  • Resolution: 1.85 Å
  • R-Value Free: 0.208 
  • R-Value Work: 0.177 
  • R-Value Observed: 0.179 

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Structural and functional analysis of Campylobacter jejuni PseG: a udp-sugar hydrolase from the pseudaminic acid biosynthetic pathway.

Rangarajan, E.S.Proteau, A.Cui, Q.Logan, S.M.Potetinova, Z.Whitfield, D.Purisima, E.O.Cygler, M.Matte, A.Sulea, T.Schoenhofen, I.C.

(2009) J Biol Chem 284: 20989-21000

  • DOI: https://doi.org/10.1074/jbc.M109.012351
  • Primary Citation of Related Structures:  
    3HBM, 3HBN

  • PubMed Abstract: 

    Flagella of the bacteria Helicobacter pylori and Campylobacter jejuni are important virulence determinants, whose proper assembly and function are dependent upon glycosylation at multiple positions by sialic acid-like sugars, such as 5,7-diacetamido-3,5,7,9-tetradeoxy-l-glycero-l-manno-nonulosonic acid (pseudaminic acid (Pse)). The fourth enzymatic step in the pseudaminic acid pathway, the hydrolysis of UDP-2,4-diacetamido-2,4,6-trideoxy-beta-l-altropyranose to generate 2,4-diacetamido-2,4,6-trideoxy-l-altropyranose, is performed by the nucleotide sugar hydrolase PseG. To better understand the molecular basis of the PseG catalytic reaction, we have determined the crystal structures of C. jejuni PseG in apo-form and as a complex with its UDP product at 1.8 and 1.85 A resolution, respectively. In addition, molecular modeling was utilized to provide insight into the structure of the PseG-substrate complex. This modeling identifies a His(17)-coordinated water molecule as the putative nucleophile and suggests the UDP-sugar substrate adopts a twist-boat conformation upon binding to PseG, enhancing the exposure of the anomeric bond cleaved and favoring inversion at C-1. Furthermore, based on these structures a series of amino acid substitution derivatives were constructed, altering residues within the active site, and each was kinetically characterized to examine its contribution to PseG catalysis. In conjunction with structural comparisons, the almost complete inactivation of the PseG H17F and H17L derivatives suggests that His(17) functions as an active site base, thereby activating the nucleophilic water molecule for attack of the anomeric C-O bond of the UDP-sugar. As the PseG structure reveals similarity to those of glycosyltransferase family-28 members, in particular that of Escherichia coli MurG, these findings may also be of relevance for the mechanistic understanding of this important enzyme family.

  • Organizational Affiliation

    Department of Biochemistry, McGill University, Montreal, Quebec H3G 1V6, Canada.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
UDP-sugar hydrolase282Campylobacter jejuni subsp. jejuni NCTC 11168 = ATCC 700819Mutation(s): 1 
Gene Names: PseG (Cj1312)
Find proteins for Q0P8U5 (Campylobacter jejuni subsp. jejuni serotype O:2 (strain ATCC 700819 / NCTC 11168))
Explore Q0P8U5 
Go to UniProtKB:  Q0P8U5
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ0P8U5
Sequence Annotations
  • Reference Sequence
Small Molecules
Experimental Data & Validation

Experimental Data

  • Resolution: 1.85 Å
  • R-Value Free: 0.208 
  • R-Value Work: 0.177 
  • R-Value Observed: 0.179 
  • Space Group: P 41
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 94.442α = 90
b = 94.442β = 90
c = 43.566γ = 90
Software Package:
Software NamePurpose
HKL-2000data collection
HKL-2000data reduction
HKL-2000data scaling

Structure Validation

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Ligand Structure Quality Assessment 

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2009-05-26
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Source and taxonomy, Version format compliance
  • Version 1.2: 2021-10-13
    Changes: Database references, Derived calculations
  • Version 1.3: 2023-09-06
    Changes: Data collection, Refinement description
  • Version 1.4: 2023-11-22
    Changes: Data collection