Bilateral BBSRC NSF/BIO - Synthetic gene circuits to measure and mitigate translational stress during heterologous protein expression

Biotechnology uses recombinant gene expression to produce a range of medicines, including insulin, vaccines, and new anti-cancer therapeutic agents based upon antibodies. For instance, the human insulin gene has been introduced into the bacterium E. coli to drive the production of this valuable medicine in the new bacterial host, cheaply and safely. In this proposal, an interdisciplinary team of biologists and physicists will establish novel technologies to improve the ability of a cell to make recombinant proteins at higher efficiency, and with greater accuracy, improving the quality, yield, cost-effectiveness and safety of next-generation medicines.

Most products of biotechnology are proteins, long chains of units called amino acids, of which there are 20 different varieties. The structures of proteins, and the sequence of their amino acids, are determined by genes, DNA strands of nucleotides with a specific sequence. To make a protein, the coding information locked in the sequence of nucleotides within the gene is first copied into a messenger RNA (mRNA), also composed of nucleotides. Then a molecular machine in the cell called a ribosome reads the information within the mRNA to produce the correct chain of amino acids, forming the protein, in a process called translation. The sequence of amino acids in the protein defines its properties and function. When a cell is programmed to produce a recombinant protein, errors can occur during translation, when an amino acid is selected to add to the protein. These errors can change the nature of the manufactured protein, and can make it defective; in the case of a protein being used as a medicine, this can prevent effective treatment, and as a worst case scenario, represent a danger to the patient.

In this proposal, the research team will work with a biotechnology company to develop sensitive devices to detect this type of error, and use them to understand how and when the cellular protein manufacturing machinery makes mistakes, so they can be minimised in the future. The team will then use assemblies of genes in a synthetic biology approach to engineer new types of cells, designed to be used in industrial fermenters, that are capable of preventing these mistakes as the proteins are produced. We will use advanced mathematical models to guide the design and safety of these new synthetic biology gene circuits. Overall, the interdisciplinary approach described in this proposal will involve biologists and physicists working together to create systems that improve production of new generations of effective medicines. To allow these improvements, it will also provide insight into the fundamental mechanisms a cell uses to express its genes and make recombinant proteins accurately. More broadly, it will indicate clear routes to optimise production of a range of modified proteins important for biotechnology and medicine.