Hybrid acyl-CoA desaturases investigated regarding structure in relation to functionality and specificity

Sammanfattning

The use of insect sex pheromones in integrated pest management (IPM) systems offers an environmentally friendly alternative to chemical pesticides. However, widespread commercial use of pheromones is limited by high production costs and environmental concerns related to the chemistry of synthetic production. A promising solution is to express insect desaturase enzymes in plants, which could enable biological production of pheromone precursors. Such precursors can be used as raw material for further synthesis to pheromones. This project has investigated if hybrid desaturases, constructed from structural membrane domains of a plant desaturase (ADS1 from Arabidopsis thaliana) and the active sites of insect desaturases (AtrΔ11, DmeΔ9, and Cpo_CPRQ) could be transiently expressed in the plant Nicotiana benthamiana. Wild type insect desaturases were functionally expressed in leaf tissue and their expected pheromone precursors were produced, but none of the constructed hybrid desaturases retained functionality. Furthermore, the plant desaturase ADS1, used as a scaffold for the hybrids, also failed to show activity when expressed in Nicotiana benthamiana, which suggests compatibility issues or mislocalization in this system. However, a potentially novel finding was made, where leaves infiltrated with the DmeΔ9 wild-type gene produced both the presumed target pheromone precursor 14:1 Z9, as well as a second precursor 16:1 Z11, which likely indicates an elongation of the desaturated products. The results of the study have demonstrated the complexity of metabolic engineering in plant systems and that successful development of hybrid desaturases is highly dependent on scaffold selection, enzyme localization and host compatibility.