The biosynthesis of oxylipins of linoleic and arachidonic acids by the sewage fungus Leptomitus lacteus, including the identification of 8R-hydroxy-9Z,12Z-octadecadienoic acid


Fox S., Akpinar A. , Prabhune A., Friend J., Ratledge C.

LIPIDS, vol.35, no.1, pp.23-30, 2000 (Journal Indexed in SCI) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 35 Issue: 1
  • Publication Date: 2000
  • Doi Number: 10.1007/s11745-000-0490-5
  • Title of Journal : LIPIDS
  • Page Numbers: pp.23-30

Abstract

When the sewage fungus Leptomitus lacteus was grown in liquid culture aerobically and then transferred to medium containing long-chain fatty acids, it produced a number of oxygenated fatty acids. From linoleic acid (18:2n-6), the major metabolite produced was R-8-hydroxy-9Z,12Z-octadecadienoic acid (8R-HODE), with additional quantities of 8,11-di-HODE, :11,16-di-HODE, and 11,17-di-HODE. Other fatty acid derivatives identified included 7-HODE, 10-HODE, and 13-hydroxy-octadecamonoenoic acid. Arachidonic acid (20:4n-6) was metabolized primarily to 18- and 19-hydroxy-eicosatetraenoic,acids (18- and 19-HETE) also as R enantiomers, along with Smaller quantities of 17-HETE, 9-HETE, 14,15-dihydroxy-eicosatrienoic acid and 11,12,19-trihydroxy-eicosatrienoic acid. The oxygenated products of long-chain fatty acids, in particular the biosynthesis of 8R-HODE, a compound classified as a precocious sporulation inducer, were similar to those produced by an unrelated fungal species in the Ascomycota, the take-all fungus Gaeumannomyces graminis. As in G. graminis, the biotransformation of linoleate to 8R-HODE was not significantly inhibited by exposure of the organism to CO. This indicated-that the enzyme responsible for 8R-HODE biosynthesis in Leptomitus could be similar to that of G. graminis; yet we did not detect:7,8-di-HODE as a product of 18:2n-6 metabolism as in G. graminis. CO did inhibit the biosynthesis of 14,15-di-HETE, 18-HETE,and 19-HETE in L. lacteus, which suggested the involvement of a cytochrome P-450-type monooxygenase. The biosynthesis: of 8R-HODE from 18:2n-6 was found to occur in certain cell lysates, specifically in low speed (15,000 x g) supernatant, following cell disruption.