Development of a Cell-Free Synthetic Biology Platform

Abstract

Cell-free systems allow for a reliable and consistent expression of recombinant proteins outside of a living cell, bypassing issues with genetic regulation and cellular noise (Hodgman and Jewett, 2012). Such systems are advantageous over cell-based synthetic biology due to the capability of tolerating toxins normally detrimental to the cell, increased freedom of design, reduced risk for biocontamination, and a rapid design-build-test cycle. Emerging as a new platform for synthetic biology, cell-free systems have shown potential for use in a variety of applications, including biofuel production, biomanufacturing, health and medicine. However, current cell-free systems are inaccessible due to their high cost or incredibly laborious lab work required to reproduce them. The goal of this work is to develop a completely customizable and accessible cell-free system composed of 38 proteins required for transcription and translation. Each protein is designed with a hexa-histidine tag on the N or C terminus to allow for easy nickel-sepharose purification. Protein overexpression and purification is verified using sodium dodecyl sulfate polyacrylamide electrophoresis (SDS- PAGE), and all 38 proteins are reconstituted to form a function cell-free system. 8 proteins have currently been successfully overexpressed and confirmed by SDS-PAGE.

To simplify the process, multiple proteins are purified at once by combining cell pellets from multiple overexpressions and purifying them on a single nickel-sepharose column. The concentrations of purified proteins will be determined using mass spectroscopy. Preliminary results include successful multi-protein purification of four proteins (Release Factor 3, Histidine Synthetase, Tryptophan Synthetase and Ribosome Recycling Factor) on a single nickel-sepharose column, subsequently verified by SDS-PAGE. Future goals for this work include complete overexpression and purification of all 38 proteins, followed by functional validation. Ultimately, this work will provide a safe and customizable cell-free system for protein production.

REFERENCE

Hodgman, C.E. and M.C. Jewett, Cell-Free Synthetic Biology: Thinking Outside the Cell.

Metabolic Engineering, 2012. 14(3): p. 261-269.