1XUU

Crystal structure of sialic acid synthase (NeuB) in complex with Mn2+ and Malate from Neisseria meningitidis


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.9 Å
  • R-Value Free: 0.238 
  • R-Value Work: 0.207 

wwPDB Validation 3D Report Full Report


This is version 1.2 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: 10.1074/jbc.M411942200
  • Primary Citation of Related Structures:  

  • 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 catalyz ...

    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: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
polysialic acid capsule biosynthesis protein SiaC
A
349Neisseria meningitidisMutation(s): 0 
Gene Names: synC (siaC)
Find proteins for Q57265 (Neisseria meningitidis)
Go to UniProtKB:  Q57265
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
MN
Query on MN

Download SDF File 
Download CCD File 
A
MANGANESE (II) ION
Mn
WAEMQWOKJMHJLA-UHFFFAOYSA-N
 Ligand Interaction
MLT
Query on MLT

Download SDF File 
Download CCD File 
A
D-MALATE
(2R)-2-HYDROXYBUTANEDIOIC ACID; 2-HYDROXY-SUCCINIC ACID
C4 H6 O5
BJEPYKJPYRNKOW-UWTATZPHSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.9 Å
  • R-Value Free: 0.238 
  • R-Value Work: 0.207 
  • Space Group: P 21 21 2
Unit Cell:
Length (Å)Angle (°)
a = 58.767α = 90.00
b = 76.147β = 90.00
c = 77.482γ = 90.00
Software Package:
Software NamePurpose
CNSrefinement
SOLVEphasing
DENZOdata reduction
SCALEPACKdata scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2004-11-02
    Type: Initial release
  • Version 1.1: 2008-04-30
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Derived calculations, Version format compliance