5EJM

ThDP-Mn2+ complex of R413A variant of EcMenD soaked with 2-ketoglutarate for 35 min


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.72 Å
  • R-Value Free: 0.192 
  • R-Value Work: 0.164 
  • R-Value Observed: 0.165 

wwPDB Validation   3D Report Full Report


This is version 1.1 of the entry. See complete history


Literature

Two active site arginines are critical determinants of substrate binding and catalysis in MenD, a thiamine-dependent enzyme in menaquinone biosynthesis.

Qin, M.M.Song, H.G.Dai, X.Chen, Y.Z.Guo, Z.H.

(2018) Biochem J 

  • DOI: 10.1042/BCJ20180548
  • Primary Citation of Related Structures:  
    5Z2U, 5Z2P, 5Z2R, 5EJM

  • PubMed Abstract: 
  • The bacterial enzyme MenD, or 2-succinyl-5-enolpyruvyl-6-hydroxy-3-cyclohexene-1-carboxylate (SEPHCHC) synthase, catalyzes an essential Stetter reaction in menaquinone (vitamin K2) biosynthesis via thiamine diphosphate (ThDP)-bound tetrahedral post-d ...

    The bacterial enzyme MenD, or 2-succinyl-5-enolpyruvyl-6-hydroxy-3-cyclohexene-1-carboxylate (SEPHCHC) synthase, catalyzes an essential Stetter reaction in menaquinone (vitamin K2) biosynthesis via thiamine diphosphate (ThDP)-bound tetrahedral post-decarboxylation intermediates. The detailed mechanism of this intermediate chemistry, however, is still poorly understood, but of significant interest given that menaquinone is an essential electron transporter in many pathogenic bacteria. Here, we used site-directed mutagenesis, enzyme kinetic assays, and protein crystallography to reveal an active-inactive intermediate equilibrium in MenD catalysis and its modulation by two conserved active site arginine residues. We observed that these conserved residues play a key role in shifting the equilibrium to the active intermediate by orienting the C 2 -succinyl group of the intermediates through strong ionic hydrogen bonding. We found that when this interaction is moderately weakened by amino acid substitutions, the resulting proteins are catalytically competent with the C 2 -succinyl group taking either the active or the inactive orientation in the post-decarboxylation intermediate. When this hydrogen-bonding interaction was strongly weakened, the succinyl group was re-oriented by 180° relative to the native intermediate, resulting in the reversal of the stereochemistry at the reaction center that disabled catalysis. Interestingly, this inactive intermediate was formed with a distinct kinetic behavior, likely as a result of a non-native mode of enzyme-substrate interaction. The mechanistic insights gained from these findings improve our understanding of the new ThDP-dependent catalysis. More importantly, the non-native-binding site of the inactive MenD intermediate uncovered here provides a new target for the development of antibiotics.


    Organizational Affiliation

    Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China chguo@ust.hk.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
2-succinyl-5-enolpyruvyl-6-hydroxy-3-cyclohexene-1-carboxylate synthaseABCDEFGH556Escherichia coli K-12Mutation(s): 1 
Gene Names: menDb2264JW5374
EC: 2.2.1.9
Find proteins for P17109 (Escherichia coli (strain K12))
Explore P17109 
Go to UniProtKB:  P17109
Protein Feature View
Expand
  • Reference Sequence
Small Molecules
Ligands 4 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
TD5
Query on TD5

Download Ideal Coordinates CCD File 
A, B, C, D, E, F, G, H
(4~{R})-4-[3-[(4-azanyl-2-methyl-pyrimidin-5-yl)methyl]-4-methyl-5-[2-[oxidanyl(phosphonooxy)phosphoryl]oxyethyl]-1,3-thiazol-3-ium-2-yl]-4-oxidanyl-butanoic acid
C16 H25 N4 O10 P2 S
ZWUKRGPVMMTMAF-GFCCVEGCSA-O
 Ligand Interaction
GOL
Query on GOL

Download Ideal Coordinates CCD File 
A, B, C, D, E, F, G, H
GLYCEROL
C3 H8 O3
PEDCQBHIVMGVHV-UHFFFAOYSA-N
 Ligand Interaction
EDO
Query on EDO

Download Ideal Coordinates CCD File 
A, B, C, D, E, F, G, H
1,2-ETHANEDIOL
C2 H6 O2
LYCAIKOWRPUZTN-UHFFFAOYSA-N
 Ligand Interaction
MN
Query on MN

Download Ideal Coordinates CCD File 
A, B, C, D, E, F, G, H
MANGANESE (II) ION
Mn
WAEMQWOKJMHJLA-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.72 Å
  • R-Value Free: 0.192 
  • R-Value Work: 0.164 
  • R-Value Observed: 0.165 
  • Space Group: P 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 90.66α = 76.07
b = 90.67β = 83.29
c = 169.37γ = 64.32
Software Package:
Software NamePurpose
PHENIXrefinement
iMOSFLMdata reduction
Aimlessdata scaling
PHASERphasing

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2016-11-02
    Type: Initial release
  • Version 1.1: 2018-11-28
    Changes: Data collection, Database references, Derived calculations