HKUST iGEM Team 2017:

Knock-Out Switch

Project Description:

Numerous iGEM teams have designed biological devices that do not sufficiently emphasize their circuit safety measures nor do they have designed standardised safety switches. In order to address this problem, we wish to standardise a well designed synthetic circuit by which the safeness safety and ethics associated with using synthetic biology as mean can be dealt with, without compromising the function of the construct that is originally designed. Such a system has the potential uses on both single and multicellular organisms for different applications - including but not limited to bioremediation, therapeutics and biosensors.

In our design, we employ luxR gene that forms a transcriptionally active complex with 3OC6HSL to activate a downstream construct. Once activated, the desired functions of the circuit will run along with a "time bomb" that terminates this synthetic process. This process is sustained by a positive feedback loop, during which the signal (3OC6HSL) will be produced continuously, thus activating equivalent systems in the genetically modified population. After a period of time (which varies depending on the application), termination of function will be accomplished by knocking out the genes of interest using Cre-lox and/or Dre-rox. As a result, the entire local population of genetically modified organisms can be reverted back to its wild-type phenotype with or without getting exterminated to prevent sudden and drastic changes in the ecosystem.