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ShZIS

Targeting both the prevention and extermination of T. urticae, we aim to produce 7-epi-zingiberene (7epiZ), a sesquiterpene that is found to have repellent, fecundity-reducing, and fatal effects towards T. urticae. In order to continue to synthesize 7epiZ after the production of Z,Z-FPP, we introduce ShZIS, a sesquiterpene synthase which catalyzes the reaction of 2Z,6Z-FPP and converts it into 7epiZ. Through discovering and exploring the catalytic effects of ShZIS, we provide future iGEM teams with a novel and effective biological catalyst able to produce a sesquiterpene from an isoprenyl diphosphate.

Essential Information

Sequences

Sequence and Features

Usage and Biology

ShZIS is a sesquiterpene synthase derived from Solanum habrochaites (an accession of the wild tomato species), and is present and expressed in the tomato's glandular trichomes. By utilizing three isoprenoid units, ShZIS catalyzes the formation of sesquiterpenes, a compound with 15 carbons. Intermediates that are commonly used include isopentenyl diphosphate (IPP), dimethylallyl diphosphate (DMAPP), and (E,E)-α-farnesyl diphosphate (FPP). Originally, it is used to produce secondary metabolites that don't directly interfere plant growth but are useful in fragrance to repel and exterminate pests. We constructed a novel sesquiterpene synthesis pathway in E. coli. Using glucose as our raw material, we introduce the MVA pathway, which transforms glucose into dimethylallyl diphosphate (DMAPP) and isopentenyl diphosphate (IPP). Afterwards, SltNPPS, a neryl diphosphate synthase catalyze the production of NPP from IPP and DMAPP. Mvan4662 is then introduced to catalyze the formation of Z,Z-FPP. In the end, ShZIS transforms Z,Z-FPP into 7epiZ.

Characterization

7-epi-zingiberene (7epiZ), having repellent, fecundity-reducing, and toxic effects on the Tetranychidae mites, is a crucial ingredient of our acaricide. To produce it, we introduced two plasmids to E. coli: pMVA, which introduces the enzymes of the Mevalonate pathway, and pW1-ZIS-NPPS-Mvan4662, which introduces the subsequent enzymes necessary for the production of 7epiZ [Fig1A], [Fig1B]. The enzyme LA2167ZIS(ZIS), the zingiberene synthethase presented in this part, is introduced with Mvan4662Q93S(Mvan4662), a Z,Z-farnesyl diphosphate (Z,Z-FPP) synthase, and SltNPPS(NPPS) a neryl pyrophosphate synthase (NPP), to E. coli via plasmid expression [Fig1C]. The three enzymes are cloned into the vector pW1, giving pW1-ZIS-NPPS-Mvan4662. Coding sequences for ZIS is placed closest to the promoter to increase its expression level, for we believe it will likely be the rate-limiting enzyme of the three.

pW1-ZIS-Mvan4662-SltNPPS, via golden gate cloning, is transformed into E. coli strain DH5ɑ. After having sequence verified, plasmids are transformed into pMVA DH5ɑ competent cells. The resultant strain is thus capable of producing zingiberene using glucose as the sole carbon source.

The pW1-ZIS-Mvan4662-SltNPPS+pMVA DH5ɑ strain is induced by IPTG and its fermentation is carried out with dodecane as the solvent. The products are collected, and GC-MS analysis and structure elucidation results [Fig3A], [Fig3B] suggest that the desired 7epiZ is produced.

Our products also underwent quantitative analysis using caryophyllene as an internal standard according to the method described in the study of Zhang, Suping, et al.[1] According to the GC-MS analysis, the production of 7epiZ is 740mg/L [Fig4A&B].

Reference

[1]Zhang, Suping, et al. ‘De Novo Biosynthesis of Alpha-Zingiberene from Glucose in Escherichia Coli’. Biochemical Engineering Journal, vol. 176, Dec. 2021, p. 108188. DOI.org (Crossref), https://doi.org/10.1016/j.bej.2021.108188.