A new class of fatty acid allene oxide formed by the DOX-P450 fusion proteins of human and plant pathogenic fungi, C. immitis and Z. tritici.
2016 (English)In: Journal of Lipid Research, ISSN 0022-2275, E-ISSN 1539-7262, Vol. 57, no 8, 1518-1528 p.Article in journal (Refereed) Published
Linoleate dioxygenase-cytochrome P450 (DOX-CYP) fusion enzymes are common in pathogenic fungi. The DOX domains form hydroperoxy metabolites of 18:2n-6, which can be transformed by the CYP domains to 1,2- or 1,4-diols, epoxy alcohols, or to allene oxides. We have characterized two novel allene oxide synthases (AOSs), namely, recombinant 8R-DOX-AOS of Coccidioides immitis (causing valley fever) and 8S-DOX-AOS of Zymoseptoria tritici (causing septoria tritici blotch of wheat). The 8R-DOX-AOS oxidized 18:2n-6 sequentially to 8R-hydroperoxy-9Z,12Z-octadecadienoic acid (8R-HPODE) and to an allene oxide, 8R(9)-epoxy-9,12Z-octadecadienoic acid, as judged from the accumulation of the α-ketol, 8S-hydroxy-9-oxo-12Z-octadecenoic acid. The 8S-DOX-AOS of Z. tritici transformed 18:2n-6 sequentially to 8S-HPODE and to an α-ketol, 8R-hydroxy-9-oxo-12Z-octadecenoic acid, likely formed by hydrolysis of 8S(9)-epoxy-9,12Z-octadecadienoic acid. The 8S-DOX-AOS oxidized [8R-(2)H]18:2n-6 to 8S-HPODE with retention of the (2)H-label, suggesting suprafacial hydrogen abstraction and oxygenation in contrast to 8R-DOX-AOS. Both enzymes oxidized 18:1n-9 and 18:3n-3 to α-ketols, but the catalysis of the 8R- and 8S-AOS domains differed. 8R-DOX-AOS transformed 9R-HPODE to epoxy alcohols, but 8S-DOX-AOS converted 9S-HPODE to an α-ketol (9-hydroxy-10-oxo-12Z-octadecenoic acid) and epoxy alcohols in a ratio of ∼1:2. Whereas all fatty acid allene oxides described so far have a conjugated diene impinging on the epoxide, the allene oxides formed by 8-DOX-AOS are unconjugated.
Place, publisher, year, edition, pages
2016. Vol. 57, no 8, 1518-1528 p.
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:uu:diva-300963DOI: 10.1194/jlr.M068981ISI: 000380752300018PubMedID: 27282156OAI: oai:DiVA.org:uu-300963DiVA: diva2:953023
FunderSwedish Research Council, K2013-67X-06523-31-3Knut and Alice Wallenberg Foundation, KAW 2004.0123