21ENGBIO: Plant microcompartment engineering for green production

The myriad pressures on the environment and industry mean that greener methods must be developed for producing the materials and products society needs. Plants provide the majority of the renewable products and materials we use, and through engineering provide tremendous opportunities to further innovate upon their uses in the bioeconomy to achieve profitable, scalable, sustainable production.

This Engineering Biology Breakthroughs Award research will engineer an innovative system based on bacterial microcompartments to expand the potential of plants as biofactories for industries from biomedicine to bioplastics.
It's key aims are to:
(1) install a bacterial microcompartment shell within plants as a scaffold for encapsulating novel enzymes,
(2) encapsulate an industrially relevant enzyme catalyst within a plant-produced microcompartment as a proof-of-concept for this engineering approach.

This project will generate the proof-of-concept required to deliver breakthroughs in how we can use plants to fuel a greener, more environmentally sustainable future.

The proposed research takes inspiration from the specialised metabolic modules within bacteria known as bacterial microcompartments (BMCs). These BMCs carry out a diversity of roles by encapsulating specific enzymes for a pathway, and trafficking metabolite movement through a proteinaceous shell, thus creating a specialised microenvironment isolated from the rest of cell metabolism. Extensive studies within bacteria have identified the proteins involved, how shells form, and the ability of modified BMC proteins to target novel protein cargo to within the BMC.

Using the protein production powerhouse that is the plant chloroplast, we propose a novel approach to engineer a simplified form of a ethanolamine utilization (Eut) BMC within tobacco chloroplasts as a protein scaffold to build biofactories. The routine nature of tobacco chloroplast transformation, its non-food status, and high biomass production capabilities make it ideal for producing plant microcompartments and their encapsulated proteins at scale. Plants provide a solar powered, self-maintaining and self-replicating means of production.

Within this proposal we intend to establish a minimal shell, and encapsulate both the marker protein gfp, and a PHA synthase for proof-of-concept, relevant to industrial scale production of biopolymers. The ability to selectively purify BMCs also provides the foundation of product recovery from plant material, to enable scalable, cost-effective processing. This will provide the basis for future engineering of plant BMCs as a production system for low cost, large scale production of biomolecules powered by - but isolated from - plant metabolism.