2PUR

Structure of dihydrodipicolinate synthase mutant Thr44Ser at 1.7 A.


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.70 Å
  • R-Value Free: 0.207 
  • R-Value Work: 0.179 
  • R-Value Observed: 0.180 

wwPDB Validation   3D Report Full Report


This is version 1.3 of the entry. See complete history


Literature

Specificity versus catalytic potency: The role of threonine 44 in Escherichia coli dihydrodipicolinate synthase mediated catalysis.

Dobson, R.C.Perugini, M.A.Jameson, G.B.Gerrard, J.A.

(2009) Biochimie 91: 1036-1044

  • DOI: 10.1016/j.biochi.2009.05.013
  • Primary Citation of Related Structures:  
    2PUR

  • PubMed Abstract: 
  • In plants and bacteria, the branch point of (S)-lysine biosynthesis is the condensation of (S)-aspartate-beta-semialdehyde and pyruvate, a reaction catalysed by dihydrodipicolinate synthase (DHDPS, E.C. 4.2.1.52). In this study, we probe the function of threonine 44 in Escherichia coli DHDPS, with respect to its role in the proton relay ...

    In plants and bacteria, the branch point of (S)-lysine biosynthesis is the condensation of (S)-aspartate-beta-semialdehyde and pyruvate, a reaction catalysed by dihydrodipicolinate synthase (DHDPS, E.C. 4.2.1.52). In this study, we probe the function of threonine 44 in Escherichia coli DHDPS, with respect to its role in the proton relay. Removal of the hydroxyl moiety of threonine 44, by mutation to valine, significantly attenuates activity (0.1% of wild-type) because the proton relay is broken. It was thus predicted that mutation of threonine 44 to serine would re-establish the proton relay and thus enzymatic activity. Following site-directed mutagenesis and purification to yield the DHDPS-Thr44Ser mutant enzyme, kinetic and structural studies were undertaken. The crystal structure of DHDPS-Thr44Ser showed that the active site was intact and that Ser44 and Tyr107 have some conformational flexibility, which is consistent with the observed loss of activity compared to the wild-type enzyme. Electron density was observed at the active site of DHDPS-Thr44Ser, which was identified as a trapped pyruvate analogue, alpha-ketoglutarate. The activity was indeed found to be increased relative to DHDPS-Thr44Val, but was still reduced to only approximately 8% of that of the wild-type enzyme. Interestingly, there was a shift in the kinetic mechanism, from the substituted-enzyme mechanism, observed in the wild-type, to the ternary-complex mechanism, consistent with the trapped substrate analogue. Increased flexibility in the active site appears to facilitate the binding/reaction of substrate analogues, suggesting that wild-type DHDPS has evolved a relatively rigid active site in order to maintain substrate specificity for pyruvate.


    Organizational Affiliation

    Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria, Australia. rdobson@unimelb.edu.au



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Dihydrodipicolinate synthaseA, B292Escherichia coliMutation(s): 1 
Gene Names: dapA
EC: 4.2.1.52 (PDB Primary Data), 4.3.3.7 (UniProt)
UniProt
Find proteins for P0A6L2 (Escherichia coli (strain K12))
Explore P0A6L2 
Go to UniProtKB:  P0A6L2
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP0A6L2
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
PO4
Query on PO4

Download Ideal Coordinates CCD File 
D [auth A],
F [auth B]
PHOSPHATE ION
O4 P
NBIIXXVUZAFLBC-UHFFFAOYSA-K
 Ligand Interaction
GOL
Query on GOL

Download Ideal Coordinates CCD File 
G [auth B]GLYCEROL
C3 H8 O3
PEDCQBHIVMGVHV-UHFFFAOYSA-N
 Ligand Interaction
K
Query on K

Download Ideal Coordinates CCD File 
C [auth A],
E [auth B]
POTASSIUM ION
K
NPYPAHLBTDXSSS-UHFFFAOYSA-N
 Ligand Interaction
Modified Residues  1 Unique
IDChainsTypeFormula2D DiagramParent
KGC
Query on KGC
A, B L-PEPTIDE LINKINGC11 H18 N2 O6LYS
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.70 Å
  • R-Value Free: 0.207 
  • R-Value Work: 0.179 
  • R-Value Observed: 0.180 
  • Space Group: P 31 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 121.04α = 90
b = 121.04β = 90
c = 110.319γ = 120
Software Package:
Software NamePurpose
REFMACrefinement
CrystalCleardata collection
d*TREKdata reduction
d*TREKdata scaling
AMoREphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2008-05-27
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Non-polymer description, Version format compliance
  • Version 1.2: 2018-01-24
    Changes: Structure summary
  • Version 1.3: 2021-10-20
    Changes: Database references, Derived calculations