Engineering synthetic gene circuits to tune membrane protein production

Alexandra Trigg (Aston University, UK)

17:30 - 17:45 Wednesday 15 April Afternoon

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Abstract

The production of membrane proteins is vital in the discovery of medicines, biopesticides, antifungals, and the delivery of vaccines. However, obtaining high yields of functional membrane protein remains a significant challenge. Heterologous expression of membrane proteins is often highly cytotoxic due to disruption of native membrane structure, saturation of endogenous chaperone and secretion systems and high translational burdens. Current methods to improve the yield of recombinant membrane protein involve trial and error approaches. To address these limitations, we are aiming to develop a gene circuit in the commonly used host Escherichia coli that can integrate multiple cellular stress responses to dynamically tune membrane protein synthesis. To examine the cellular stresses activated during recombinant production of membrane proteins, an endogenous stress-related promoter was cloned into a reporter plasmid expressing green fluorescent protein (GFP). Production of an inner membrane (IM) protein YiaM, part of the YiaMNO tripartite ATP-independent periplasmic (TRAP) transporter, was induced in E. coli C41 (DE3) harbouring a reporter plasmid. GFP production, corresponding to stress promoter activation, was measured over a 16-hour induction period during which YiaM was produced. Analysis of reporter gene production demonstrated that envelope stress promoters were significantly activated during membrane protein production. Alternative membrane proteins were tested with the same reporter plasmids, demonstrating robustness of the stress response during membrane protein production. Use of a cell envelope stress promoter in our feedback loop will allow autonomous control of membrane protein synthesis to decrease toxicity and improve yield.

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