3K8E

Crystal structure of E. coli lipopolysaccharide specific CMP-KDO synthetase


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.51 Å
  • R-Value Free: 0.234 
  • R-Value Work: 0.199 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Structure-based mechanism of CMP-2-keto-3-deoxymanno-octulonic acid synthetase: convergent evolution of a sugar-activating enzyme with DNA/RNA polymerases

Heyes, D.J.Levy, C.Lafite, P.Roberts, I.S.Goldrick, M.Stachulski, A.V.Rossington, S.B.Stanford, D.Rigby, S.E.J.Scrutton, N.S.Leys, D.

(2009) J.Biol.Chem. 284: 35514-35523

  • DOI: 10.1074/jbc.M109.056630
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • The enzyme CMP-Kdo synthetase (KdsB) catalyzes the addition of 2-keto-3-deoxymanno-octulonic acid (Kdo) to CTP to form CMP-Kdo, a key reaction in the biosynthesis of lipopolysaccharide. The reaction catalyzed by KdsB and the related CMP-acylneuramina ...

    The enzyme CMP-Kdo synthetase (KdsB) catalyzes the addition of 2-keto-3-deoxymanno-octulonic acid (Kdo) to CTP to form CMP-Kdo, a key reaction in the biosynthesis of lipopolysaccharide. The reaction catalyzed by KdsB and the related CMP-acylneuraminate synthase is unique among the sugar-activating enzymes in that the respective sugars are directly coupled to a cytosine monophosphate. Using inhibition studies, in combination with isothermal calorimetry, we show the substrate analogue 2beta-deoxy-Kdo to be a potent competitive inhibitor. The ligand-free Escherichia coli KdsB and ternary complex KdsB-CTP-2beta-deoxy-Kdo crystal structures reveal that Kdo binding leads to active site closure and repositioning of the CTP phosphates and associated Mg(2+) ion (Mg-B). Both ligands occupy conformations compatible with an S(n)2-type attack on the alpha-phosphate by the Kdo 2-hydroxyl group. Based on strong similarity with DNA/RNA polymerases, both in terms of overall chemistry catalyzed as well as active site configuration, we postulate a second Mg(2+) ion (Mg-A) is bound by the catalytically competent KdsB-CTP-Kdo ternary complex. Modeling of this complex reveals the Mg-A coordinated to the conserved Asp(100) and Asp(235) in addition to the CTP alpha-phosphate and both the Kdo carboxylic and 2-hydroxyl groups. EPR measurements on the Mn(2+)-substituted ternary complex support this model. We propose the KdsB/CNS sugar-activating enzymes catalyze the formation of activated sugars, such as the abundant CMP-5-N-acetylneuraminic acid, by recruitment of two Mg(2+) to the active site. Although each metal ion assists in correct positioning of the substrates and activation of the alpha-phosphate, Mg-A is responsible for activation of the sugar-hydroxyl group.


    Organizational Affiliation

    Manchester Interdisciplinary Biocentre, Faculty of Life Sciences, University of Manchester, 131 Princess Street, Manchester M1 7DN.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
3-deoxy-manno-octulosonate cytidylyltransferase
C, D, A, B
264Escherichia coli (strain K12)Mutation(s): 0 
Gene Names: kdsB
EC: 2.7.7.38
Find proteins for P04951 (Escherichia coli (strain K12))
Go to UniProtKB:  P04951
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.51 Å
  • R-Value Free: 0.234 
  • R-Value Work: 0.199 
  • Space Group: C 1 2 1
Unit Cell:
Length (Å)Angle (°)
a = 124.470α = 90.00
b = 77.180β = 90.03
c = 143.630γ = 90.00
Software Package:
Software NamePurpose
DNAdata collection
PHASERphasing
REFMACrefinement
XDSdata reduction
XSCALEdata scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2009-11-10
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Advisory, Version format compliance
  • Version 1.2: 2012-12-05
    Type: Database references