Team:Tokyo Tech/Experiment/C6

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Construction of the 3OC6HSL-dependent 3OC12HSL production module

Fig2-1-3-1-2, Las sender strain and Las reporter strain

For construction of the 3OC6HSL-dependent 3OC12HSL production module, we firstly constructed a new part Plux-LasI (BBa_K934022). Plux-LasI cell is an engineered E.coli that contains a 3OC6HSL-dependent LasI generator and a constitutive LuxR generator. As a 3OC6HSL-dependent LasI generator, we constructed a new Biobrick part Plux-LasI (BBa_K934022) by combining Plux promoter (BBa_R0062) and LasI (BBa_K081016 ). As a constitutive LuxR generator, we used Ptet-LuxR (BBa_S03119). By introducing Plux-LasI (BBa_K934022 ) and Ptet-LuxR (BBa_S03119) into E.coli strain JM2.300, we constructed Plux-LasI cell. Then we performed a reporter assay by using Las reporter cell to characterize the function of Plux-LasI (BBa_K934022) . As the negative control of 3OC12HSL production, we prepared 3OC12HSL non-producer cell (ΔP-LasI cell) that contains, in addition to Ptet-LuxR (BBa_S03119), promoterless-LasI (BBa_K081016) instead of Plux-LasI (BBa_K934022) (Fig2-1-3-1-2).

The ⊿P-LasI cell does not produce 3OC12HSL even though 3OC6HSL exist. The supernatants of the cultures of these modules were used as the inducer in the reporter assay (Fig2-1-3-1-3). We prepared four conditions as follow.

Fig2-1-3-1-3, How to perform 3OC6HSL-dependent 3OC12HSL production assay

A) Culture containing Plux-LasI cell without 3OC6HSL induction

B) Culture containing Plux-LasI cell with 3OC6HSL induction

C) Culture containing ⊿P-LasI cell without 3OC6HSL induction

D) Culture containing ⊿P-LasI cell with 3OC6HSL induction

Using the supernatant of the four culture conditions, we performed the reporter assay.

In the reporter assay, we used a Las reporter strain that contains Ptrc-LasR and Plas-GFP (BBa_K649001). Also, a reporter cell that expresses GFP constitutively and a reporter cell that does not express GFP were used as the positive control and the negative control, respectively.




Fig2-1-3-1-4, 3OC6HSL-dependent 3OC12HSL production

Fig2-1-3-1-4 shows fluorescence intensities by the reporter cells dependent on different conditions. Only when the supernatant of condition B was used, the fluorescence intensity of the Las reporter cell increased, while the supernatants of other three conditions did not affect. Comparing the results of the condition A and B, it can be said that with the induction of 3OC6HSL to Plux-LasI cell, the fluorescence intensity of the LasI reporter cell increased by 20-folds. This result indicates that Plux-LasI cell produced 3OC12HSL in response to 3OC6HSL induction by the function of Plux-LasI (BBa_K934022 ). From this experiment, we confirmed that a new part Plux-LasI (BBa_K934022 ) synthesized enough concentration of 3OC12HSL to induce the Las reporter cell. [Protocol]











Materials & Methods

[back to the project page "3OC12HSL production module"]

1.Construction

A) Sender cells


pSB6A1-Ptet-LuxR / pSB3K3-Plux-LasI (JM2.300)…Plux-LasI cell

Positivefeedbackassay13tokyotech.png


pSB6A1-Ptet-LuxR / pSB3K3-ΔP-LasI (JM2.300)…ΔP-LasI cell

Positivefeedbackassay5tokyotech.png










B) Reporter cells


pSB6A1-Ptrc-LasR / pSB3K3-Plas-GFP (JM2.300)…Las reporter cell

Positivefeedbackassay7tokyotech.png


pSB6A1-Ptrc-LasR / pSB3K3-ΔP-GFP (JM2.300)…negative control

Positivefeedbackassay9tokyotech.png


pSB6A1-Ptrc-LasR / pSB3K3-pλ-GFP (JM2.300)…positive control

Positivefeedbackassay10tokyotech.png

2.Strain

JM2.300

Protocol

[Go to the project page "Construction of the 3OC6HSL-dependent 3OC12HSL production module"]

1. collect liquid culture

1.1 Prepare overnight culture of inducer cell at 37°C for 12hours.

1.2 Take 30μl of the overnight culture of inducer cell into LB(3ml) + antibiotics (Amp 50μg/ml + Kan 30μg/ml).(→fresh culture)

1.3 Incubate the flesh culture of inducer cell until the observed OD600 reaches around 0.50. Centrifuge the cell at 5000g, 25°C, 1 min, suspend it with 1ml LB + antibiotics (Amp 50μg/ml).

1.4 Take 30μl cell suspensions into LB(3ml) + antibiotics (Amp 50μg/ml + Kan 30μg/ml) + 5μM 3OC6HSL(3μl) and LB(3ml) + antibiotics (Amp 50μg/ml + Kan 30μg/ml) + DMSO(3μl).

1.5 Incubate the 3OC12HSL producer cells for another 4 hours at 37°C.

1.6 Centrifuge the 3OC12HSL producer cells at 9000g, 4°C, 1 min, and filter the cultured cells.

1.7 Dilute the filtrate by LB + antibiotics (Amp + Kan) in 1:30.

2 Reporter assay

2.1 Prepare overnight culture of reporter cell at 37°C for 12hours.

2.2 Take 30μl of the overnight culture of reporter cell into LB(3ml) + antibiotics (Amp 50μg/ml + Kan 30μg/ml). (→fresh culture)

2.3 Incubate the flesh culture of reporter cell until the observed OD600 reaches around 0.50, and gather the supernatant of culture of inducer cell.

2.4 Centrifuge the reporter cell at 5000g, 25°C, 1 min, and take it into LB + antibiotics (Amp 50μg/ml + Kan 30μg/ml).

2.5 Add 30μl samples of process 2.4 to filtrate + LB(3ml) + antibiotics (Amp 50μg/ml + Kan 30μg/ml) from process 1.7

3OC6HSL Plux
++
-+
+ -
- -

2.6 Incubate the reporter cells for 4 hours at 37°C.

2.7 Flow cytometer measurements for GFP expression of reporter cells.

[Go to the project page "Construction of the 3OC6HSL-dependent 3OC12HSL production module"]