1XUZ

Crystal structure analysis of sialic acid synthase (NeuB)from Neisseria meningitidis, bound to Mn2+, Phosphoenolpyruvate, and N-acetyl mannosaminitol


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.20 Å
  • R-Value Free: 0.248 
  • R-Value Work: 0.186 
  • R-Value Observed: 0.186 

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This is version 1.3 of the entry. See complete history


Literature

Structural and mechanistic analysis of sialic acid synthase NeuB from Neisseria meningitidis in complex with Mn2+, phosphoenolpyruvate, and N-acetylmannosaminitol.

Gunawan, J.Simard, D.Gilbert, M.Lovering, A.L.Wakarchuk, W.W.Tanner, M.E.Strynadka, N.C.

(2005) J Biol Chem 280: 3555-3563

  • DOI: https://doi.org/10.1074/jbc.M411942200
  • Primary Citation of Related Structures:  
    1XUU, 1XUZ

  • PubMed Abstract: 

    In Neisseria meningitidis and related bacterial pathogens, sialic acids play critical roles in mammalian cell immunity evasion and are synthesized by a conserved enzymatic pathway that includes sialic acid synthase (NeuB, SiaC, or SynC). NeuB catalyzes the condensation of phosphoenolpyruvate (PEP) and N-acetylmannosamine, directly forming N-acetylneuraminic acid (or sialic acid). In this paper we report the development of a coupled assay to monitor NeuB reaction kinetics and an 18O-labeling study that demonstrates the synthase operates via a C-O bond cleavage mechanism. We also report the first structure of a sialic acid synthase, that of NeuB, revealing a unique domain-swapped homodimer architecture consisting of a (beta/alpha)8 barrel (TIM barrel)-type fold at the N-terminal end and a domain with high sequence identity and structural similarity to the ice binding type III antifreeze proteins at the C-terminal end of the enzyme. We have determined the structures of NeuB in the malate-bound form and with bound PEP and the substrate analog N-acetylmannosaminitol to 1.9 and 2.2 A resolution, respectively. Typical of other TIM barrel proteins, the active site of NeuB is located in a cavity at the C-terminal end of the barrel; however, the positioning of the swapped antifreeze-like domain from the adjacent monomer provides key residues for hydrogen bonding with substrates in the active site of NeuB, a structural feature that leads to distinct modes of substrate binding from other PEP-utilizing enzymes that lack an analogous antifreeze-like domain. Our observation of a direct interaction between a highly ordered manganese and the N-acetylmannosaminitol in the NeuB active site also suggests an essential role for the ion as an electrophilic catalyst that activates the N-acetylmannosamine carbonyl to the addition of PEP.


  • Organizational Affiliation

    Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z3.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
polysialic acid capsule biosynthesis protein SiaC349Neisseria meningitidisMutation(s): 0 
Gene Names: neuB
UniProt
Find proteins for Q57265 (Neisseria meningitidis)
Explore Q57265 
Go to UniProtKB:  Q57265
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ57265
Sequence Annotations
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  • Reference Sequence
Small Molecules
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.20 Å
  • R-Value Free: 0.248 
  • R-Value Work: 0.186 
  • R-Value Observed: 0.186 
  • Space Group: P 21 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 58.531α = 90
b = 75.654β = 90
c = 77.866γ = 90
Software Package:
Software NamePurpose
MOSFLMdata reduction
SCALAdata scaling
SOLVEphasing
CNSrefinement
CCP4data 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: 2004-11-02
    Type: Initial release
  • Version 1.1: 2008-04-30
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Derived calculations, Version format compliance
  • Version 1.3: 2024-02-14
    Changes: Data collection, Database references, Derived calculations