, Volume 5, Issue 2-3, pp 347-357
Date: 09 Nov 2006

Formation of oxylipins by CYP74 enzymes

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Abstract

Lipid peroxidation is common to all biological systems, both appearing in developmentally and environmentally regulated processes. Products are hydroperoxy polyunsaturated fatty acids and metabolites derived there from collectively named oxylipins. They may either originate from chemical oxidation or are synthesized by the action of various enzymes, such as lipoxygenases. Cloning of many lipoxygenases and other key enzymes metabolizing oxylipins revealed new insights on oxylipin functions, new reactions and the first hints on enzyme mechanisms. These aspects are reviewed with respect to metabolism of fatty acid hydroperoxides by an atypical P450 subfamily: the CYP74. Up to now this protein family contains three different enzyme activities: (i) allene oxide synthase leading to the formation of unstable allene oxides which react to ketol and cyclopentenone fatty acids, (ii) hydroperoxide lyase producing hemiacetals decomposing to aldehydes and ω-oxo fatty acids and (iii) divinyl ether synthase which forms divinyl ethers. Signalling compounds such as jasmonates, antimicrobial and antifungal compounds such as leaf aldehydes or divinyl ethers, and a plant-specific blend of volatiles including leaf alcohols are among their numerous products.