Premium
Synthesis of a novel allene oxide from linolenic acid by a mini‐catalase/lipoxygenase fusion protein from the cyanobacterium Acaryochloris marina
Author(s) -
Brash Alan R.,
Gao Benlian,
Boeglin William E.
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.2_supplement.327
Subject(s) - chemistry , oxylipin , lipoxygenase , allene , biochemistry , linoleic acid , polyunsaturated fatty acid , catalase , fatty acid , enzyme , catalysis
A biosynthetic pathway in marine invertebrates utilizes an arachidonate 8 R ‐lipoxygenase (LOX) fused to a mini‐catalase with allene oxide synthase (AOS) function to form marine prostanoids such as the clavulones. Here we cloned a putative mini‐catalase/lipoxygenase fusion protein from the cyanobacterium Acaryochloris marina , expressed the 92 kD protein in E. coli , and purified the dark green protein by nickel affinity chromatography. We characterized the products formed from polyunsaturated fatty acids by HPLC, UV spectroscopy, MS and NMR. The unusually small A. marina LOX domain of ∼52 kD oxygenates linoleic and arachidonic acids at the ω10 position (9 R , 11 R , respectively), whereas linolenic acid, a likely natural substrate, is oxygenated with unique specificity at ω7 to 12 R ‐hydroperoxyoctadec‐9 Z ,13 E ,15 Z ‐trienoic acid. The catalase‐related domain of ∼40 kD transforms the 12 R ‐hydroperoxide to 12 R ,13‐epoxy‐9 Z ,13,15 Z ‐trienoic acid, a previously undescribed allene oxide, identified from its hydrolysis and cyclization products. The functions of allene oxides besides jasmonate and prostanoid synthesis remain to be established but may include specific signaling functions akin to the unstable oxygenated lipids of plant and mammalian biology. Supported by NIH grant GM‐074888