Difference between revisions of "Part:BBa K819007"

Revision as of 08:03, 25 September 2012

_NOTOC__ Measurement device for Luminesensor

recA408 Promoter + B0030 + GFP + ssrA-tag

A fast degrading GFP ligated to the rear of a sulA promoter in 408 form (only recognizable by our LexA-VVD fusing protein, not by E.coli endogenous LexA). The sulA promoter promotes a gene which express SulA protein, a differentiation inhibitor, and was a member of the SOS regulon family. When co-transformed with our luminesensor plasmid into E.coli cell illuminated by blue light, the light will triger the dimerizaiton of the LexA408-VVD fusion protein and the dimerized LexA408 domain will bind the SOS box in 408 form in the SulA408 promoter to inhibit the transcription of the downstream gene so that no GFP will be expressed; if the environment is dark, the luminesensor will not dimerize and no supression of the promoter will occour, and GFP will be expressed.

Cells exposed to different light intensity expressing Luminesensor showed manifest light-repressed reporter gene transcription. As shown in the figure, all of the cells with dissimilar attenuators showed incredible repression efficiency (figure 1: luminance measurement of different attenuator).

Figure 1. luminance measurement of different attenuator

GFP expression was repressed by Luminesensor expressed in light sensing cells under either bio-luminescence. To obtain more quantitative data, we measured the GFP expression level using a Tecan infinite 200 reader. As is shown in the graph below (Figure 2), the expression level of GFP in darkness (in our device with no glowing cells) is about 200-fold higher than that of the cells under bio-luminescence. The Figure 3 shows the quantitative data of GFP expression level to the dilution ratio of the light emitting cell.

Figure 2. Quantitative measurement of the repression effect of bio-luminescence

Figure 3. Measurement of relative GFP level to the dilution ratio of light emitting cell using a Tecan infinite 200 reader

Sequence and Features