Detection of unprecedented allene oxide synthase member of CYP74B subfamily: CYP74B33 of carrot (Daucus carota)

Publication date: Available online 19 July 2019Source: Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of LipidsAuthor(s): Svetlana S. Gorina, Fakhima K. Mukhitova, Tatiana M. Ilyina, Yana Y. Toporkova, Alexander N. GrechkinAbstractEnzymes of CYP74 family widespread in higher plants control the metabolism of fatty acid hydroperoxides to numerous bioactive oxylipins. Hydroperoxide lyases (HPLs, synonym: hemiacetal synthases) of CYP74B subfamily belong to the most common CYP74 enzymes. HPLs isomerize the hydroperoxides to the short-lived hemiacetals, which are spontaneously decomposed to aldehydes and aldoacids. All CYP74Bs studied yet except the CYP74B16 (flax divinyl ether synthase, LuDES) possessed the 13-HPL activity. Present work reports the cloning of the expressed CYP74B33 gene of carrot (Daucus carota L.) and studies of catalytic properties of the recombinant CYP74B33 protein. In contrast to all CYP74B proteins studied yet, CYP74B33 behaved differently in few respects. Firstly, the preferred substrates of CYP74B33 are 9-hydroperoxides. Secondly and most importantly, CYP74B33 exhibits the 9-allene oxide synthase (AOS) activity. For example, the 9(S)-hydroperoxide of linoleic acid (9-HPOD) underwent the conversion to α-ketol via the short-lived allene oxide. Uncommonly, the 9-HPOD conversion affords a minority of cis-10-oxo-11-phytoenoic acid, which is also produced by CYP74C but not the CYP74A AOSs. The similar product patterns were observed upon the in...
Source: Biochimica et Biophysica Acta (BBA) Molecular and Cell Biology of Lipids - Category: Lipidology Source Type: research