A microgravity responsive synthetic genetic device in Escherichia coli.

Bioengineering solutions to human space travel must consider microgravity as an important component. Thus, one of the fundamental challenges of space bioengineering is to create cellular microgravity responsive device, which integrate microgravity as a signal within biochemical and cellular processes. Here, we designed, fabricated and characterized the first biochemical and cellular microgravity responsive device using an engineered genetic circuit in E.coli, which responded to microgravity by changing the expression of a target enhanced green fluorescent gene (EGFP). Our device design was based on the deregulation of HfQ protein in E.coli in microgravity, which was translated through HfQ mediated silencing of EGFP by anti-EGFP synthetic small regulatory RNAs. This resulted a reduced silencing (~28 times) of the EGFP in microgravity. We demonstrated that the basic design of the device is universal in nature for E.coli, by creating multiple successful devices, where target genes (EGFP, TdTomato, and FtsZ) and the promoters (inducible and constitutive) were altered. Further, we applied this device to control the cell division process by microgravity. Here we targeted the cell division regulator FtsZ, which resulted an elongated cell shape in normal gravity and this deformed cell shape got rescued to normal one by applying microgravity. The work showed for the first time, a way to integrate microgravity as a physical signal within biochemical processes of a living cell in a human designed way and thus, may have significance in space bioengineering and synthetic biology.