Linoleate 9R-dioxygenase and allene oxide synthase activities of Aspergillus terreus

Arch Biochem Biophys. 2010 Mar 1;495(1):67-73. doi: 10.1016/j.abb.2009.12.022. Epub 2010 Jan 4.

Abstract

Oxygenation of linoleic acid by Aspergillus terreus was studied with LC-MS/MS. 9(R)-Hydroperoxy-10(E),12(Z)-octadecadienoic acid (9R-HpODE) was identified along with 10(R)-hydroxy-8(E),12(Z)-octadecadienoic acid and variable amounts of 8(R)-hydroxy-9(Z),12(Z)-octadecadienoic acid. 9R-HpODE was formed from [11S-2H]18:2n-6 with loss of the deuterium label, suggesting antarafacial hydrogen abstraction and oxygenation. Two polar metabolites were identified as 9-hydroxy-10-oxo-12(Z)-octadecenoic acid (alpha-ketol) and 13-hydroxy-10-oxo-11(E)-octadecenoic acid (gamma-ketol), likely formed by spontaneous hydrolysis of an unstable allene oxide, 9(R),10-epoxy-10,12(Z)-octadecadienoic acid. alpha-Linolenic acid and 20:2n-6 were oxidized to hydroperoxy fatty acids at C-9 and C-11, respectively, but alpha- and gamma-ketols of these fatty acids could not be detected. The genome of A. terreus lacks lipoxygenases, but contains genes homologous to 5,8-linoleate diol synthases and linoleate 10R-dioxygenases of aspergilli. Our results demonstrate that linoleate 9R-dioxygenase linked to allene oxide synthase activities can be expressed in fungi.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aspergillus / enzymology*
  • Aspergillus / genetics
  • Fatty Acids / metabolism
  • Genome, Bacterial
  • Hydrogen Peroxide / metabolism
  • Intramolecular Oxidoreductases / genetics
  • Intramolecular Oxidoreductases / metabolism*
  • Linoleic Acid / metabolism*
  • Oxidation-Reduction
  • Transcription, Genetic

Substances

  • Fatty Acids
  • Linoleic Acid
  • Hydrogen Peroxide
  • Intramolecular Oxidoreductases
  • hydroperoxide isomerase