Enzymatic Cascade in Pseudomonas that Produces Pyrazine from α-Amino Acids

Chembiochem. 2020 Feb 3;21(3):353-359. doi: 10.1002/cbic.201900448. Epub 2019 Nov 6.


Pyrazines are widespread chemical compounds that include pheromones and odors. Herein, a novel mechanism used by Pseudomonas fluorescens SBW25 to biosynthesize monocyclic pyrazines is reported. Heterologous expression of the papABC genes that synthesize the natural α-amino acid 4-aminophenylalanine (4APhe), together with three adjacent papDEF genes of unknown function, in Escherichia coli resulted in the production of 2,5-dimethyl-3,6-bis(4-aminobenzyl)pyrazine (DMBAP), which comprised two symmetrical aminobenzyl moieties derived from 4APhe. It is found that PapD is a novel amino acid C-acetyltransferase, which decarboxylates and transfers acetyl residues to 4APhe, to generate an α-aminoketone, which spontaneously dehydrates and condenses to give dihydro DMBAP. PapF is a novel oxidase in the amine oxidase superfamily that oxidizes dihydro DMBAP to yield the pyrazine ring of DMBAP. These two enzymes constitute a unique mechanism for synthesizing monocyclic pyrazines and might serve as a novel strategy for the enzymatic synthesis of pyrazine derivatives from natural α-amino acids.

Keywords: amino acids; biosynthesis; nitrogen heterocycles; oxidases; transferases.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetyltransferases / chemistry
  • Acetyltransferases / metabolism*
  • Amino Acids / chemistry
  • Amino Acids / metabolism*
  • Molecular Structure
  • Oxidoreductases / chemistry
  • Oxidoreductases / metabolism*
  • Pseudomonas fluorescens / enzymology*
  • Pyrazines / chemistry
  • Pyrazines / metabolism*


  • Amino Acids
  • Pyrazines
  • Oxidoreductases
  • Acetyltransferases