Construction of an artificial cell capable of protein expression at low temperatures using a cell extract derived from Pseudomonas fluorescens

Abstract

A liposome-based artificial cell (LBAC) consists of a liposome encapsulating a cell-free protein expression system (CFPES) and protein-encoding DNA. It is surrounded by a lipid bilayer membrane and synthesizes proteins that resemble actual cells. Hence, they have been one of the most studied artificial cells. According to recent studies, they have been able to sense bio-functional molecules by synthesizing fluorescent proteins in response to target molecules. Therefore, they are expected to be used as biosensors. However, previously reported LBACs encapsulated the CFPES derived from Escherichia coli, resulting in the most productive protein expression at 20–40◦C. To broaden the range of their working temperatures to lower temperatures, in this study, we constructed LBACs using a CFPES derived from Pseudomonas fluorescens that grows at a temperature range of 4◦C to 30◦C. We then demonstrated that the constructed LBAC expressed proteins at 8◦C and that, the protein expression capability of the LBAC derived from P. fluorescens was four-fold higher than that derived from E. coli at 8◦C. This study will pave the way for the development of artificial cell-based biosensors that work in cold environments or for the synthesis of heat-labile proteins in LBACs.