Synthesis of 12-aminododecenoic acid by coupling transaminase to oxylipin pathway enzymes

Oxylipin biosynthesis via an unprecedented 16-hydroperoxide lyase pathway in green tissues of cucumber (Cucumis sativus L.) plants

The plant lipoxygenase cascade is a source of various regulatory oxylipins that play a role in cell signalling, stress adaptation, and immune response. Recently, we detected an unprecedented 16(S)-lipoxygenase, CsLOX3, in the leaves and fruit pericarp of cucumber (Cucumis sativus L.). In the present work, an array of products biosynthesized through the conversions of α-linolenic acid 16-hydroperoxide (16-HPOT) was detected. Firstly, a prominent 15-hydroxy-9,12-pentadecadienoic acid (Me/TMS) was detected, the product of hydroperoxide lyase (HPL) chain cleavage of 16-HPOT and further reduction of aldehyde 15-oxo-9,12-pentadecadienoic acid to alcohol. Besides, the presence of dicarboxylic acid, 3,6-pentadecadiene-1,15-dioic acid, was deduced from the detection of its catalytic hydrogenation product, pentadecane-1,15-dioic acid. Finally, 12,15-dihydroxypentadecanoic acid (Me/TMS) was detected amongst the hydrogenated products, thus indicating the presence of the parent 12,15-dihydroxy-9,13-pentadecadienoic acid. To confirm the proposed HPL chain cleavage, the 16(S)-HPOT was prepared and incubated with the recombinant cucumber HPL CYP74B6 enzyme. The CYP74B6 possessed high activity towards 16-HPOT. Chain cleavage yields the (9Z,12Z)-15-oxo-9,12-pentadecadienoic acid, undergoing a spontaneous isomerization into (9Z,13E)-15-oxo-9,13-pentadecadienoic acid. Thus, the cucumber plants as well as the recombinant cucumber HPL CYP74B6 possessed unprecedented 16-HPL activity, cleaving 16-HPOT into a C15 fragment, 15-oxo-9,12-pentadecadienoic acid, and a complementary volatile C3 fragment, propionic aldehyde. The 16-LOX/16-HPL route of oxylipin biosynthesis presents a novel facet of the plant LOX pathway.

Whole-cell one-pot biosynthesis of dodecanedioic acid from renewable linoleic acid

BACKGROUND

Dodecanedioic acid (DDA), a typical medium-chain dicarboxylic fatty acid with widespread applications, has a great synthetic value and a huge industrial market demand. Currently, a sustainable, eco-friendly and efficient process is desired for dodecanedioic acid production.

RESULTS

Herein, a multi-enzymatic cascade was designed and constructed for the production of DDA from linoleic acid based on the lipoxygenase pathway in plants. The cascade is composed of lipoxygenase, hydroperoxide lyase, aldehyde dehydrogenase, and unidentified double-bond reductase in E. coli for the main cascade reactions, as well as NADH oxidase for cofactor recycling. The four component enzymes involved in the cascade were co-expressed in E. coli, together with the endogenous double-bond reductase of E. coli. After optimizing the reaction conditions of the rate-limiting step, 43.8 g L- 1 d- 1 of DDA was obtained by a whole-cell one-pot process starting from renewable linoleic acid.

CONCLUSIONS

Through engineering of the reaction system and co-expressing the component enzymes, a sustainable and eco-friendly DDA biosynthesis route was set up in E. coli, which afforded the highest space time yield for DDA production among the current artificial multi-enzymatic routes derived from the LOX-pathway, and the productivity achieved here ranks the second highest among the current research progress in DDA biosynthesis.

Epoxyalcohol Synthase Branch of Lipoxygenase Cascade

Oxylipins are one of the most important classes of bioregulators, biosynthesized through the oxidative metabolism of unsaturated fatty acids in various aerobic organisms. Oxylipins are bioregulators that maintain homeostasis at the cellular and organismal levels. The most important oxylipins are mammalian eicosanoids and plant octadecanoids. In plants, the main source of oxylipins is the lipoxygenase cascade, the key enzymes of which are nonclassical cytochromes P450 of the CYP74 family, namely allene oxide synthases (AOSs), hydroperoxide lyases (HPLs), and divinyl ether synthases (DESs). The most well-studied plant oxylipins are jasmonates (AOS products) and traumatin and green leaf volatiles (HPL products), whereas other oxylipins remain outside of the focus of researchers' attention. Among them, there is a large group of epoxy hydroxy fatty acids (epoxyalcohols), whose biosynthesis has remained unclear for a long time. In 2008, the first epoxyalcohol synthase of lancelet Branchiostoma floridae, BfEAS (CYP440A1), was discovered. The present review collects data on EASs discovered after BfEAS and enzymes exhibiting EAS activity along with other catalytic activities. This review also presents the results of a study on the evolutionary processes possibly occurring within the P450 superfamily as a whole.