The Switch Specifics

Our aim was to develop a switch with three distinct states and each of them represents an arbitrary gene. In contrast to Uppsala 2012’s solution of such a switch, we designed a mechanism that can be fully controlled with only one wavelength. Such a switch can be used for example in bioreactors to achieve higher level of control over the bioprocess and to switch between different phases of the process. The benefit of our system is that it reserves only one channel of communication but it would still enable an accurate control over the three states.

Parts

Background

Using our Team Seeker tool, we first found out who are the teams and key players who have done similar research. We were primarily interested in light receptors, genetic switches, lambda repressor and effective transcription factors. As the first iGEM team from Finland, our aim was to build a solid base on our work and minimize the need to design our own BioBricks.

The Peking 2012 team [1] designed an ultra-sensitive light sensor for luminescence. They combined a LOV domain, dimerizing domain and a DNA-binding LexA domain. Such protein becomes active when the cells are illuminated with 440 - 480 nm light. In active form, the dimerizing domains facilitate formation of LexA dimer which is able to bind DNA and repress transcription in only such form. Whereas their light sensing system seems to work very well there were two issues with it. Firstly, their light sensing system was not available and secondly, it might have been too sensitive; controlling the light at very low intensities could be rather challenging.

The Uppsala 2011 team [2]
SJTU-BioX-Shanghai
Jeff Tabor lab

[Kuva circuitista]
The switch is based on a protein called cI (http://www.uniprot.org/uniprot/P03034). This protein coding sequence is under a promoter that is activated by FixJ, a protein that is phosphorylated and therefore activated by another protein, called YF1. YF1 is phosphorylated and activated in dark. [Lisää!]

We have designed the circuit by using both already existing biobricks and synthesized parts.

We are currently assembling the prototype of our system.

References

1. Peking 2012 iGEM Team: https://2012.igem.org/Team:Peking
2. Uppsala-Sweden 2011 iGEM Team: https://2011.igem.org/Team:Uppsala-Sweden
3. SJTU BioX Shanghai 2013 iGEM Team: https://2013.igem.org/Team:SJTU-BioX-Shanghai

Our Research Methods

LED-rig for excitation

We designed a new kind of device from scratch. Inspired by the Tabor labs

1. E.J. Olson, L.A. Hartsough, B.P. Landry, R. Shroff, J.J. Tabor,
   "Characterizing bacterial gene circuit dynamics with optically programmed gene expression signals."
   Nature Methods 11(4), 449-455 (2014).

Results

Discussion