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From 2011.igem.org

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Module 3: Gene Guard

Containment is a serious issue concerning the release of genetically modified organisms (GMOs) into the environment. To prevent horizontal gene transfer of the genes we are expressing in our chassis, we have developed a system based on the genes encoding holin, anti-holin and endolysin. We are engineering anti-holin into the genome of our chassis, where it acts as an anti-toxin, and holin and endolysin on plasmid DNA. In the event of horizontal gene transfer with a soil bacterium, holin and endolysin will be transferred without anti-holin, rendering the recipient cell non-viable and effectively containing the Auxin Xpress and Phyto-Route genes in our chassis.

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Overview

For human practices to inform the design of our project, we decided to come up with a novel solution to minimising the risk of releasing GMOs into the environment. We tried to think beyond containment and kill-switch mechanisms and asked the questions, what would the worst-case scenario be if we were to release our GMO into the wild? And how can we avoid these issues?

One of most problematic consequences of GMO release is horizontal gene transfer of non-natural plasmid DNA to existing soil bacteria.

Gene guard is a novel mechanism to prevent horizontal gene transfer and therefor is a viable solution for preventing the exchange of genetic material for a GMO to natural microbes. It will use a toxin/anti-toxin system where anti-holin will be integrated into the Escherichia coli genome and will prevent the holin and endolysin in the plasmids to lyse the cell. Therefore, if the plasmid is ever transferred to any other bacterial species which is not our own strain, it will lyse thereby containing the genetic information within our GMO.

For more information on our Human Practices approach to GM release click here.

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