Biochemical characterisation of the Glycyl Radical Enzyme Containing Microcompartment (GRM2) from Proteus mirabilis

The production of bio-therapeutic proteins, small molecule drugs and chemical intermediates of industrial interest in recombinant hosts is becoming an increasingly popular alternative to production in mammalian cell culture, natural hosts (e.g. plants, fungi) or chemical synthesis, which can be slow and expensive. Achieving high product yields in recombinant synthetic pathways requires that the fluxes of each enzymatic reaction of the pathway of interest be balanced to limit the accumulation of intermediates, particularly those toxic to the host. Conventional strategies include the modulation of expression levels of individual enzymes or directed evolution of rate-limiting enzymes and have focused on balancing pathway flux, but don't consider other crucial factors such as diffusion, transport, localisation of intermediates and the cost-effective purification and recovery of products. Nature has developed strategies to deal with many of these issues by confining certain biochemical pathways to various organelles. In prokaryotes, bacterial microcompartments (BMCs) encapsulate enzymes associated with certain metabolic processes within a large protein shell, bringing sequentially acting enzymes into spatial proximity thus increasing local enzyme concentration, protecting the cell from potentially reactive intermediates and facilitating co-factor recycling. In the past decade significant progress has been made to engineer BMCs to permit the construction of BMC bioreactors with novel functions within the cell.

The overall aim of this project is to develop BMCs as synthetic biology platforms for spatial organization of enzymes for enhanced production of valuable compounds in E. coli. The project will expand our understanding of the fundamentals of engineering synthetic compartmentalisation, the benefits and limitations of pathway localisation and inform the rational design of future microcompartment-derived technologies.

The project is aligned with the EPSRC centre for Doctoral Training in Bioprocess Engineering Leadership. It provides new synthetic biology approaches to the redesign of cellular chemistry and will impact in the development of cost-effective and sustainable bio-based manufacture.

BMC tools and technologies will be developed with industrial applications in mind. The work is supported by in-kind contribution from the industrial biotechnology company Ingenza, a world leader in the application of synthetic biology for the provision of efficient bioprocesses for the manufacture of chemicals, biologics, pharmaceuticals and biofuels. Compartmentalisation of enzymes/pathways may provide a valuable strategy for the improvement of industrial strains of interest. The industrial partner will offer enzymes/pathways of interest and advice/consultancy on how industry would like to see the BMC technology applied.