1DJO

Crystal structure of Pseudomonas 7A Glutaminase-asparaginase with the inhibitor donv covalently bound in the active site


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2 Å
  • R-Value Free: 0.238 
  • R-Value Work: 0.214 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Reactions of Pseudomonas 7A glutaminase-asparaginase with diazo analogues of glutamine and asparagine result in unexpected covalent inhibitions and suggests an unusual catalytic triad Thr-Tyr-Glu.

Ortlund, E.Lacount, M.W.Lewinski, K.Lebioda, L.

(2000) Biochemistry 39: 1199-1204

  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Pseudomonas 7A glutaminase-asparaginase (PGA) catalyzes the hydrolysis of D and L isomers of glutamine and asparagine. Crystals of PGA were reacted with diazo analogues of glutamine (6-diazo-5-oxo-L-norleucine, DON) and asparagine (5-diazo-4-oxo-L-no ...

    Pseudomonas 7A glutaminase-asparaginase (PGA) catalyzes the hydrolysis of D and L isomers of glutamine and asparagine. Crystals of PGA were reacted with diazo analogues of glutamine (6-diazo-5-oxo-L-norleucine, DON) and asparagine (5-diazo-4-oxo-L-norvaline, DONV), which are known inhibitors of the enzyme. The derivatized crystals remained isomorphous to native PGA crystals. Their structures were refined to crystallographic R = 0.20 and R(free) = 0.24 for PGA-DON and R = 0.19 and R = 0.23 for PGA-DONV. Difference Fourier electron density maps clearly showed that both DON and DONV inactivate PGA through covalent inhibition. Continuous electron density connecting the inhibitor to both Thr20 and Tyr34 of the flexible loop was observed providing strong evidence that Thr20 is the primary catalytic nucleophile and that Tyr34 plays an important role in catalysis as well. The unexpected covalent binding observed in the PGA-DON and PGA-DONV complexes shows that a secondary reaction involving the formation of a Tyr34-inhibitor bond takes place with concomitant inactivation of PGA. The predicted covalent linkage is not seen, however, suggesting an alternative method of inhibition not yet seen for these diazo analogues. These surprising results give insight as to the role of the flexible loop Thr and Tyr in the catalytic mechanism.


    Organizational Affiliation

    Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
GLUTAMINASE-ASPARAGINASE
A, B
330Pseudomonas sp. (strain ATCC 29598 / 7A)Mutation(s): 0 
Gene Names: ansB
EC: 3.5.1.38
Find proteins for P10182 (Pseudomonas sp. (strain ATCC 29598 / 7A))
Go to UniProtKB:  P10182
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
CAB
Query on CAB

Download SDF File 
Download CCD File 
A, B
4,4-dihydroxy-5-oxo-L-norvaline
C5 H9 N O5
NKTBKFGHLWDKLW-VKHMYHEASA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2 Å
  • R-Value Free: 0.238 
  • R-Value Work: 0.214 
  • Space Group: C 2 2 21
Unit Cell:
Length (Å)Angle (°)
a = 78.370α = 90.00
b = 135.890β = 90.00
c = 137.560γ = 90.00
Software Package:
Software NamePurpose
CNSphasing
CNSrefinement
DENZOdata reduction
SCALEPACKdata scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2000-01-24
    Type: Initial release
  • Version 1.1: 2008-04-27
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Derived calculations, Source and taxonomy, Version format compliance