Coprinopsis cinerea dioxygenase is an oxygenase forming 10(S)-hydroperoxide of linoleic acid, essential for mushroom alcohol, 1-octen-3-ol, synthesis

1-Octen-3-ol is a volatile oxylipin found ubiquitously in Basidiomycota and Ascomycota. The biosynthetic pathway forming 1-octen-3-ol from linoleic acid via the linoleic acid 10(S)-hydroperoxide was characterized 40 years ago in mush-rooms, yet the enzymes involved are not identified. The dioxy-genase 1 and 2 genes (Ccdox1 and Ccdox2) in the mushroom Coprinopsis cinerea contain an N-terminal cyclooxygenase-like heme peroxidase domain and a C-terminal cytochrome P450 -related domain. Herein, we show that recombinant CcDOX1 is responsible for dioxygenation of linoleic acid to form the 10(S)-hydroperoxide, the first step in 1-octen-3-ol synthesis, whereas CcDOX2 conceivably forms linoleic acid 8-hydroperoxide. We demonstrate that KO of the Ccdox1 gene suppressed 1-octen-3-ol synthesis, although added linoleic acid 10(S)-hydroperoxide was still efficiently converted. The P450 -related domain of CcDOX1 lacks the characteristic Cys heme ligand and the evidence indicates that a second uncharacterized enzyme converts the 10(S)-hydroperoxide to 1-octen-3-ol. Additionally, we determined the gene KO strain (Delta Ccdox1) was less attractive to fruit fly larvae, while the feeding behavior of fungus gnats on Delta Ccdox1 mycelia showed little difference from that on the mycelia of the WT strain. The proliferation of fun-givorous nematodes on Delta Ccdox1 mycelia was similar to or slightly worse than that on WT mycelia. Thus, 1-octen-3-ol seems to be an attractive compound involved in emitter- receiver ecological communication in mushrooms.

Automated summary

1-Octen-3-ol is a volatile oxylipin commonly found in Basidiomycota and Ascomycota. The biosynthetic pathway of 1-octen-3-ol from linoleic acid has been characterized, but the enzymes involved are still unknown. This study identifies two genes, Ccdox1 and Ccdox2, in the mushroom Coprinopsis cinerea, and shows that CcDOX1 is responsible for the first step of 1-octen-3-ol synthesis. The study also suggests the involvement of another enzyme in the conversion of the intermediate compound. Furthermore, the study demonstrates the importance of 1-octen-3-ol in ecological communication in mushrooms.