Gene Guard
As our project suggests the release of genetically modified organisms (GMOs) into the environment, we feel it is necessary to reduce the risk of horizontal gene transfer. To prevent horizontal gene transfer of the genes, we have designed a system based on the genes encoding holin/endolysin and anti-holin, Colicin-E3 and Colicin Immunity E3, Endonuclease EcoRI and Methyltransferase EcoRI. There is no doubt that our multi-containment system is more secure than a single-containment system.

Holin/Endolysin will be carried on a plasmid and the anti-holin on the genomic DNA. The other gene pairs act in the same the way (Fig. 7-2-1). Anti-holin will prevent the holin and endolysin encoded on the plasmids to lyse the cell. However, if the plasmid is transferred to any other bacterial that is not our modified bacteria, it will induce cell lysis, thereby preventing the spread of genetic information contained in our genetically modified bacteria. And the other gene pairs act in the same the way. Therefore, we can prevent the transfer of synthetic genes into wild type bacteria by our treble safe guard.

Fig. 7-2-1 Gene guard system.

[1] Grundling A, et al. Holins kill without warning. Proceedings of the National Academy of Sciences of the United States of America, 2001, 98: 9348-9352.
[2] Masaki H and Ohta T. Colicin E3 and its immunity genes. Journal of Molecular Biology, 1985, 182: 217-227.
[3] Hopkins BB and Reich NO. Simultaneous DNA Binding, Bending, and Base Flipping EVIDENCE FOR A NOVEL M. EcoRI METHYLTRANSFERASE-DNA COMPLEX. Journal of Biological Chemistry, 2004, 279: 37049-37060.