Difference between revisions of "Part:BBa K608014"

Revision as of 11:46, 21 September 2011

strong promoter and medium RBS with RFP

This part consists of a strong promotor with medium RBS and tagged with RFP to quantify the expression.

The RFP fluorescence was measured with a plate reader:

The fluorescence intensity and protein concentration were measured with the FLUOstar Omega,
which is a multi-mode microplate reader. Samples were pipetted into the microplate and analyzed via the plate reader. In this experiment we focused on the protein concentration and the fluorescence intensity of RFP. We measured the protein concentration with the bradford-assay. This is a method to determine the total protein To analyze the protein concentration of the samples, Coomassie Brillant Blue was pippeted to each sample. With the binding of the dye to the proteins the color changes from dark red to blue. The more protein in the solution the more Coomassie dye can bind to proteins and the more the color changes into blue. The absorption of bound Coomassie dye is 595nm. The absorbance is proportional with the amount of bound dye. With a series of Bovine Serum Albumin (BSA) measurements the exact protein concentration of the samples can be determined. BSA acts like a “marker” because the concentration of BSA is known and with a linear calibration line the exact protein concentration can be detected.

With RFP (Red Fluorescence Protein) the activity of promotor and RBS can be quantified. RFP served like GFP as a reporter to determine the expression level. RFP is excited at a wavelength of 580nm. The more RFP in the solution the more is the RFP fluorescence intensity.The plate reader illuminates the samples with a high energy xenon flash lamp. Optical filters or monochromator create the exact wavelength. The more GFP in the sample the higher is the GFP fluorescence intensity. The intensity is collected with the second optical system and is detected with a side window photomultiplier tube.

RFP fluorescence intensity dependent on the strenght of promotor and RBS

Promotor and RBS:
PR1: strong Promotor (J23104) strong RBS (B0034)
PR2: strong Promotor (J23104) medium RBS (B0032)
PR3: strong Promotor (J23104) weak RBS (B0031)
PR4: medium Promotor (J23110) strong RBS (B0034)
PR5: medium Promotor (J23110) medium RBS (B0032)
PR6: medium Promotor (J23110) weak RBS (B0031)

The results of this test show that PR2 is 39,9 times stronger than PR6. Although the PR1 should have the strongest expression of RFP, in this case PR2 had the strongest expression of RFP. The fluorescence intensity of RFP varies, and because of lack of time we could not repeat this experiment. We have also tested the promotor and RBS activity with GFP as a reporter and the results deviate from this experiment. So we are looking forward to test this system another time.

Sequence and Features