Team:Tokyo Tech

We want to make a Coli Touch!!

We try to construct a bacterial ‘touch panel’ which is colored by the pressure.

We name it Coli touch.

Until iGEM2007, input style was only heat, small molecule and light. These input style have problems. For example, Heat input occur thermal gradient, small molecule input occur concentration gradient, light input depend on location of a container. So, we thought input style except these. That is “press”. Press input has an advantage that input signal travel uniformly in a container.

We construct genetic circuits that can respond to pressure signal. Lac promoter was known as a pressure inducible promoter. Lac promoter is repressed by LacI protein. The repression is released by adding IPTG (Isopropyl β-D-1-thiogalactopyranoside). Besides IPTG induction, pressure induction is possible. Under high pressure, the affinity of lac protein for lac operon decreases by transition of Lac protein from tetramer to dimer. Through this mechanism, Lac promoter is induced by pressure.

We thought two projects, basic project and application project. Basic project consist of two categories. One is construction of pressure responsive genetic (1). The other is creating basic device for a touch display (2). Application project also consist of two categories. One is development of low pressure inducible promoter (3). The other is construction of pressure responsive toggle switch (4). In the future, we want to create the touch display made of E. coli.

We used these equipments (show figure) for pressure experiments.

We construct these plasmids (show figure).

Each part is constructed on low-copy plasmid “pSB6”.

We created pressurizing device for first step of creating touch display. This device has two holes (show figure). Each hole contains tubes and water. Inside tubes E. coli is cultivated. Pressure can travel to inside tubes. One hole (B) is covered with a block made of an acrylic glass. (show figure) Therefore the hole is not pressurized by water. The other (A) is covered with a plastic tape (show figure). Therefore the hole is pressurized.

In the stage of basic project, very high pressure (30MPa) is required for pressure induction of lac promoter. But lower pressure response is needed for creating touch display. Therefore we develop lower pressure inducible promoter. We performed random mutagenesis to lac promoter and tried to screen promoters with FACS.

A touch display are required a function of rewritable. Rewritable function consists of writable and erasable one. We adopted a genetic toggle switch that responds to pressure (show figure)