Modification of a plant-based expression system for therapeutic protein production through genetic modification of endogenous plant N-glycosylation

Plant cells are a capable system for producing economically and therapeutically important proteins for a variety of applications, and are considered a safer production system than some existing hosts such as bacteria or yeasts. However, plants do not perform modifications to proteins in the same manner as mammalian cells do, which can have far reaching consequences for their safety and effectiveness. This project aims to genetically modify tobacco plants (Nicotiana tabacum) to create a plant-based system capable of fully "humanizing" proteins of interest, whilst improving safety of final product. We aim to demonstrate that the mammalian glycosylation enzymes B4GALT1, ST6GAL, GNTIV and GNTV can be expressed in plant cells, and localise to specific cisternae of the Golgi body. In instances where enzymes are more effective within specific cisternae, such as GNTIV & GNTV in the medial-Golgi and ST6GAL & B4GALT1 in the trans-Golgi. We demonstrate strategies to modify localisation to the desired cisternae by use of construct fusions with plant Cytoplasmic-Transmembrane-Stem (CTS) regions.
This project addresses key areas of study for the British Biological Research Council (BBSRC) on new strategic approaches to industrial biotechnology. The project would offer an economically viable system for the production of high value renewables and therapeutics in a plant model organism as a low immunogenic alternative to existing systems, developed by fundamental manipulation of plant biology. This project aligns also with the BBSRC priority of 'World Class Underpinning Bioscience' as glycosylation is a critical aspect of cell functionality.