Pseudomonas fluorescens Strain R124 Encodes Three Different MIO Enzymes

Chembiochem. 2018 Feb 16;19(4):411-418. doi: 10.1002/cbic.201700530. Epub 2018 Jan 4.


A number of class I lyase-like enzymes, including aromatic ammonia-lyases and aromatic 2,3-aminomutases, contain the electrophilic 3,5-dihydro-5-methylidene-4H-imidazol-4-one (MIO) catalytic moiety. This study reveals that Pseudomonas fluorescens R124 strain isolated from a nutrient-limited cave encodes a histidine ammonia-lyase, a tyrosine/phenylalanine/histidine ammonia-lyase (XAL), and a phenylalanine 2,3-aminomutase (PAM), and demonstrates that an organism under nitrogen-limited conditions can develop novel nitrogen fixation and transformation pathways to enrich the possibility of nitrogen metabolism by gaining a PAM through horizontal gene transfer. The novel MIO enzymes are potential biocatalysts in the synthesis of enantiopure unnatural amino acids. The broad substrate acceptance and high thermal stability of PfXAL indicate that this enzyme is highly suitable for biocatalysis.

Keywords: biocatalysis; gene transfer; lyases; nitrogen; phenylalanine.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Ammonia-Lyases / chemistry
  • Ammonia-Lyases / genetics
  • Ammonia-Lyases / metabolism*
  • Biocatalysis
  • Histidine Ammonia-Lyase / chemistry
  • Histidine Ammonia-Lyase / genetics
  • Histidine Ammonia-Lyase / metabolism*
  • Imidazoles / chemistry
  • Intramolecular Transferases / chemistry
  • Intramolecular Transferases / genetics
  • Intramolecular Transferases / metabolism*
  • Molecular Structure
  • Phenylalanine Ammonia-Lyase / chemistry
  • Phenylalanine Ammonia-Lyase / genetics
  • Phenylalanine Ammonia-Lyase / metabolism*
  • Pseudomonas fluorescens / enzymology*
  • Pseudomonas fluorescens / genetics
  • Pseudomonas fluorescens / isolation & purification


  • 4-methylideneimidazole-5-one
  • Imidazoles
  • Ammonia-Lyases
  • Phenylalanine Ammonia-Lyase
  • Histidine Ammonia-Lyase
  • Intramolecular Transferases