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.
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 P450-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.
Fox
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SR
University of Hull, Department of Biological Sciences, United Kingdom. Simon.Fox@bbsrc.ac.uk
Akpinar
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A
Prabhune
A A
AA
Friend
J
J
Ratledge
C
C
D016718:Arachidonic Acid / Q000096:biosynthesis*; D006893:Hydroxyeicosatetraenoic Acids / Q000096:biosynthesis; D019787:Linoleic Acid / Q000096:biosynthesis*; D008041:Linoleic Acids / Q000032:analysis* / Q000096:biosynthesis; D009868:Oomycetes / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D012722:Sewage / Q000382:microbiology*
D006893:Hydroxyeicosatetraenoic Acids; D008041:Linoleic Acids; D012722:Sewage; C075806:8-hydroxylinoleic acid; C080024:11-hydroxy-9,12-octadecadienoic acid; C061444:18-hydroxy-5,8,11,14-eicosatetraenoic acid; D016718:Arachidonic Acid; C055986:19-hydroxy-5,8,11,14-eicosatetraenoic acid; D019787:Linoleic Acid; D010100:Oxygen