Crystallographic Trapping of Reaction Intermediates in Quinolinic Acid Synthesis by NadA

ACS Chem Biol. 2018 May 18;13(5):1209-1217. doi: 10.1021/acschembio.7b01104. Epub 2018 Apr 19.


NadA is a multifunctional enzyme that condenses dihydroxyacetone phosphate (DHAP) with iminoaspartate (IA) to generate quinolinic acid (QA), the universal precursor of the nicotinamide adenine dinucleotide (NAD(P)) cofactor. Using X-ray crystallography, we have (i) characterized two of the reaction intermediates of QA synthesis using a "pH-shift" approach and a slowly reacting Thermotoga maritima NadA variant and (ii) observed the QA product, resulting from the degradation of an intermediate analogue, bound close to the entrance of a long tunnel leading to the solvent medium. We have also used molecular docking to propose a condensation mechanism between DHAP and IA based on two previously published Pyrococcus horikoshi NadA structures. The combination of reported data and our new results provide a structure-based complete catalytic sequence of QA synthesis by NadA.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Crystallography, X-Ray
  • Molecular Docking Simulation
  • Multienzyme Complexes / chemistry*
  • Multienzyme Complexes / metabolism
  • NAD / metabolism
  • Protein Conformation
  • Quinolinic Acid / metabolism*
  • Thermotoga maritima / enzymology*


  • Multienzyme Complexes
  • NAD
  • quinolinic acid synthetase
  • Quinolinic Acid