Expression of Fusion Proteins of Aspergillus terreus Reveals a Novel Allene Oxide Synthase

Abstract

Background: Allene oxide synthases (AOS) of the CYP74 family are present in plants, but AOS of fungi have not been characterized. Results: Expression of dioxygenase-cytochrome P450 fusion proteins of Aspergillus terreus reveals a novel AOS. Conclusion: AOS of A. terreus forms compound II with catalytic similarities to CYP74 and CYP8A1. Significance: The fungal AOS protein sequence is unique with little homology to CYP74.

Discovery of a linoleate 9S-dioxygenase and an allene oxide synthase in a fusion protein of Fusarium oxysporum

“…The latter contain linoleate 8 R -DOX or 10 R -DOX in their N-terminal domains and 5,8-or 7,8-hydroperoxide isomerases or an AOS in the C-terminal CYP domains ( 18,(20)(21)(22)(23); 9 R -DOX activity could not be detected in the recombinant AOS of A. terreus . This fusion protein thus differs from the AOS of the coral Plexaura homomalla , which contains an N-terminal catalase-like domain with AOS activity and a C-terminal 8 R -LOX domain ( 24 ).…”

“…9-HPODE was prepared by photooxidation, purified by normal phase HPLC, and the S and R stereoisomers of 9-HPODE were partly separated on Reprosil Chiral NR-R ( 18,26 ); the latter contained a few percent of the S stereoisomer. 9 S -HPODE, 13 S-HPODE, 13 S -hydroperoxyoctadecatrienoic acid (HPOTrE), 13 R -HPODE, and 13 RHPOTrE were prepared enzymatically [tomato LOX ( 27 ), soybean LOX-1, and 13 R -MnLOX ( 28 )] and purifi ed by silica chromatography.…”

“…Aspergillus terreus does not form JA, but this fungus oxidizes 18:2n-6 sequentially to 9 R -hydroperoxy-10( E ),12( Z )-octadecadienoic acid (HPODE) and an allene oxide, 9 R (10)-epoxy-11,(12 Z )-octadecadienoic acid [9 R (10)-EODE] ( 17 ). The AOS was recently identifi ed in the CYP domain of a dioxygenase (DOX)-CYP fusion protein (ATEG_02036), whereas the origin of the 9 R -DOX activity could not be determined ( 18 ).…”

“…Journal of Lipid Research Volume 54, 2013 the dioxygen bonds of 8 R -HPODE, and Asn 964 of the AOS facilitates homolytic cleavage of the dioxygen bond of 9 R -HPODE ( 18,25 ). The ClustalW alignment suggests that Asn 964 and Gln 967 of the AOS of A. terreus are replaced by an acidic and an alcoholic residue, Glu 946 and Ser 949 respectively , in FOXB_01332 ( Fig.…”

A Catalase-related Hemoprotein in Coral Is Specialized for Synthesis of Short-chain Aldehydes

“…Although the plant AOS and cAOS catalyze similar reactions, the enzymes are structurally unrelated (12)(13)(14). The highly labile allene oxide products of both enzyme types readily break down to stable end products, ␣-ketol and cyclopentenone (6). Moreover, despite the structural relatedness to catalase, cAOS lacks the capability to catalyze the decomposition of hydrogen peroxide to water and molecular oxygen (14,15).…”