DXP synthase-catalyzed C-N bond formation: nitroso substrate specificity studies guide selective inhibitor design

Chembiochem. 2013 Jul 22;14(11):1309-15. doi: 10.1002/cbic.201300187. Epub 2013 Jul 3.


1-Deoxy-D-xylulose 5-phosphate (DXP) synthase catalyzes the first step in the nonmammalian isoprenoid biosynthetic pathway to form DXP from pyruvate and D-glyceraldehyde 3-phosphate (D-GAP) in a thiamin diphosphate-dependent manner. Its unique structure and mechanism distinguish DXP synthase from its homologues and suggest that it should be pursued as an anti-infective drug target. However, few reports describe any development of selective inhibitors of this enzyme. Here, we reveal that DXP synthase catalyzes C-N bond formation and exploit aromatic nitroso substrates as active site probes. Substrate specificity studies reveal a high affinity of DXP synthase for aromatic nitroso substrates compared to the related ThDP-dependent enzyme pyruvate dehydrogenase (PDH). Results from inhibition and mutagenesis studies indicate that nitroso substrates bind to E. coli DXP synthase in a manner distinct from that of D-GAP. Our results suggest that the incorporation of aryl acceptor substrate mimics into unnatural bisubstrate analogues will impart selectivity to DXP synthase inhibitors. As a proof of concept, we show selective inhibition of DXP synthase by benzylacetylphosphonate (BnAP).

Keywords: DXP synthase; biosynthesis; enzyme inhibitors; isoprenoids; kinetics; substrate specificity.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biocatalysis
  • Carbon / chemistry
  • Catalytic Domain
  • Enzyme Inhibitors / chemistry*
  • Enzyme Inhibitors / metabolism
  • Kinetics
  • Nitrogen / chemistry
  • Substrate Specificity
  • Terpenes / chemistry
  • Terpenes / metabolism
  • Transferases / chemistry
  • Transferases / metabolism*


  • Enzyme Inhibitors
  • Terpenes
  • Carbon
  • Transferases
  • deoxyxylulose-5-phosphate synthase
  • Nitrogen