Team:TU-Munich/Project/Killswitch

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A novel mechanism preventing uncontrolled spread of transgenic plants

Background – Why generate a plant which kills itself under certain conditions?

Working on plants is uncomplicated since as photoautotrophic organisms they can provide their own energy. So creating a photosensitive plant might seem silly at first glance. "Crazy, stupid Germans!", you might think, but wait, there's more! Green biotechnology doesnt have an easy stand in Germany since the "German Angst" of uncontrolled spreading of transgenic plants. Therefore, we see it as our task and duty to meet the required high safety standards that minimize these risks for a maximum of biosafety. We created a plant that can only survive in a well defined environment. Plants don't neccessarily need the whole spectrum of light to supply themselves with energy, so reassigning part of the spectrum to other purposes is possible. Shielded from red light by filters, the moss survives without compromising vitality or growth. Unintended release of our protected environment leads to activation of a lethal process of no return and thus kills the moss.

Our solution – a red light-triggered autokill system

PhyB-PIF3/PIF6 interaction under red light exposition

Phytochrome B (abbrev.: PhyB) is a plant photoreceptor that exists in two interconvertible forms Pr and Pfr. In its Pfr (far red light sensititve) form upon red light illumination, PhyB interacts with Phytochrome Interacting Factors, e. g. PIF3 or PIF6.


Phytochrome Interacting Factor 3/6 (abbrev.: PIF3/PIF6) are both transcription factors with basic helix-loop-helix (bHLH) motifs that that bind to PhyB upon red light exposition


TEV Protease is a site-specific cystein protease from the C4 peptidase family from Tabacco Etch Virus (TEV). Its typical recognition site is ENLYFQ(G/S).


Split TEV Protease is a split version of the TEV Protease which N- and C-terminal split parts shows no enzymatic activity. Bringing them to physical proximity leads to reconstitution of the cleavage activity.

Micococcal nuclease (also called: Thermonuclease, MNase) is a non-specific endo-exonuclease which shows activy in digesting single-stranded DNA/RNA and also double-stranded DNA/RNA.

Reconstitution of Split-TEV-Protease

Liberation of membrane-anchored nuclease and nuclear translocation

Disruption of the genetic material and programmed cell-death

Design of our construct

Results

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References:

http://www.ncbi.nlm.nih.gov/pubmed/6327079 Edens et al., 1984

  1. http://www.ncbi.nlm.nih.gov/pubmed/6327079 Edens et al., 1984 Edens, L., Bom, I., Ledeboer, A. M., Maat, J., Toonen, M. Y., Visser, C., and Verrips, C. T. (1984). Synthesis and processing of the plant protein thaumatin in yeast. Cell, 37(2):629–33.




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