Part:BBa_I757010:Experience

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Applications of BBa_I757010

Done by iGEM11 Potsdam_Bioware

This beta lactamase was used in combination with the TorA signal sequence (BBa_K208005) as a new protease activity detector device. The BioBrick parts BBa_K627012 and BBa_K627013 consist of the TorA signal sequence followed by a short peptide sequence used as cleavage site for different proteases (TEV (BBa_K627008-BBa_K627010) and 14_3C (BBa_K627011)) and ends with the beta lactamase.
When E.coli XL1 blue where transformed with our construct, the cells were able to survive at ampicillin concentrations up to 400 µg/ml, when incubated on agar plates over night at 37°C or at 30 °C.

Thessaly 2019 Characterization

Thessaly 2019 sought to characterize the coding sequence of TEM-optimized beta-lactamase (BBa_I757010) under the regulation of the constituve Anderson Family promoters BBa_J23100, BBa_J23105, BBa_J23106, BBa_J23119. Beta-lactamase is an enzyme that hydrolyses beta-lactams (e.g. ampicillin) and is naturally found in procaryotic cells. A colorimetric assay has been developed using nitrocefin as a substrate which after hydrolysis from beta-lactamase changes the reaction color, from yellow (380nm) to red (490nm).

To achieve that, the coding sequence was assembled with each promoter, a universal RBS (BBa_B0034) and a double terminator(BBa_B0015). The parts were cloned in pSB1C3 and pSB1K3 and transformed into E. coli DH5a competent cells. For protein expression, the plasmids were transformed into E. coli BL21 (DE3) competent cells.

For the beta-lactamase assay, we set up the following experimental design:

1. Grow BL21 (DE3) cells overnight in 5ml LB (~16h) at a shaken incubator, 37 degrees C / 210rpm

2. The following morning, measure the OD600 of overnight cultures

3. Dilute all cultures to OD600¬ = 0.05 in M9 minimal medium

4. Grow cells 37 degrees C /210 RPM until OD600=0.4-0.6 (~2h)

5. Dilute all cells to the same OD600 (e.g. 0.4)

6. Load 160 of culture in a 96-well plate (do triplicates). Add 40 ul 0.5 uM nitrocefin for a final concentration of 100nM

7. Measure the absorbance at 490nm (for nitrocefin hydrolysis) and 600nm (for cell growth) every 30 seconds for 25 minutes in a microplate reader. Shake between measurements.

To ensure that the absorbance shown corresponds only to enzymatic activity by beta-lactamase, we included 3 controls in the experiment. The first control has M9 medium only (no cells) and nitrocefin, the second has empty BL21 (DE3) cells (no plasmid) and nitrocefin, while the third has BL21 (DE3) cells containing the plasmid but not the part (empty plasmid). To obtain comparable results, we normalized all values by dividing OD490 by OD600.

The results are shown in the graph below

User Reviews

UNIQ8b052bb46b36076a-partinfo-00000001-QINU UNIQ8b052bb46b36076a-partinfo-00000002-QINU The lactamases shows great activity at 37°C and 30°C incubation over night on agar plates. The transformed E.coli cells were able to survive with ampicillin concentrations up to 400 µg/ml at 37°C and at 30°C.