3PAA : Mechanism of inactivation of E. coli aspartate aminotransferase by (S)-4-amino-4,5-dihydro-2-furancarboxylic acid (S-ADFA) pH 8.0

  • Dali Liu (Contributor)
  • Edvin V. Pozharski (Contributor)
  • Mengmeng Fu (Contributor)
  • Richard B Silverman (Contributor)
  • Dagmar Ringe (Contributor)



Experimental Technique/Method:X-RAY DIFFRACTION
Release Date:2010-12-01
Deposition Date:2010-10-19
Revision Date:2011-07-13#2017-11-08
Molecular Weight:45391.77
Macromolecule Type:Protein
Residue Count:396
Atom Site Count:3454

As a potential drug to treat neurological diseases, the mechanism-based inhibitor (S)-4-amino-4,5-dihydro-2-furancarboxylic acid (S-ADFA) has been found to inhibit the γ-aminobutyric acid aminotransferase (GABA-AT) reaction. To circumvent the difficulties in structural studies of a S-ADFA-enzyme complex using GABA-AT, l-aspartate aminotransferase (l-AspAT) from Escherichia coli was used as a model PLP-dependent enzyme. Crystal structures of the E. coli aspartate aminotransferase with S-ADFA bound to the active site were obtained via cocrystallization at pH 7.5 and 8. The complex structures suggest that S-ADFA inhibits the transamination reaction by forming adducts with the catalytic lysine 246 via a covalent bond while producing 1 equiv of pyridoxamine 5'-phosphate (PMP). Based on the structures, formation of the K246-S-ADFA adducts requires a specific initial binding configuration of S-ADFA in the l-AspAT active site, as well as deprotonation of the ε-amino group of lysine 246 after the formation of the quinonoid and/or ketimine intermediate in the overall inactivation reaction.
Date made available2010

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