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The cell-death device is required in many fields. In bioremediation, for example, this device can prevent introduced bacteria from disrupting the ecosystem. Also, It can be applied to other ideas such as E.coli capsules which scatter drug or aroma by cell-lysis responding to a certain signal. Therefore, the cell death devices based on diverse approaches, including previous iGEM projects have been developed. However, present cell-death devices are still not easy to use, because of the poor characterization or strict restriction on promoters' activity and so on. Therefore, we attempt to register on BioBrick better characterized and more useful cell-death device to contribute to every future team.

Problems of Present Cell-Death Devices

In order to design a universal and applicable cell-death device, we need to reduce the restriction on promoter's activity and to characterize the strength of the cell-death function.

1. Solution to the Restriction on Promoter's Activity

In constructing a simple circuit consisting of an inducible promoter and a killer-gene, the combinations are limited by the promoter's leak, strength of killer-function and many other factors. We looked for the solution to this problem and came up with an idea of using an Tanti-killer gene as well with two promoters (a constitutive one and an inducible one). With this circuit, we can apply more promoters to this device by using an appropriate constitutive promoter.

We considered that Lysis cassette of λ phage and its antagonist, SΔTMD1 are the most appropriate to Killer-gene and Anti-killer gene. This was because some iGEM teams in the past already dealt with lysis cassette and also because we found some articles that shows the effect of SΔTMD1 in the yeast. For more detailed explanation of LysisCassete, go LearnMore

2. Need for Characterization

In fact, there is no experimental data about the present devices in the iGEM's cell-death category. Quantitative analysis of Lysis cassette is necessary. To contribute to iGEM in this category with well characterized device, we did experimentations and some modeling.



Goal A: Characterization of R0011, a strong lactose promoter

We used R0011, which is one of the most commonly used parts in iGEM, to characterize our genes because the strength of promoter activity is very high. However, in previous iGEM, no teams didn't characterize R0011 with RPU. We tried to determine what is the ratio of activity of R0011, a lactose promoter when cell lysis occurs. Therefore, in oreder to characterize killer and anti-killer, we have to characterize R0011.

Goal B: Characterization of λ Lysis cassette

To characterize λlysiscassette, we made below construct and observed E.coli transformed with the constructs in various concentration of IPTG.


Goal C: Characterization of the anti-killer gene, SΔTMD1


E.coli transformed with the constructs below was grown in medium without IPTG and IPTG was added to the culture at proper time. The A550 of the culture was measured and the result was compared with that of the experiment of the killer gene in order to find whether the anti-killer gene works correctly.


See below pages for details.




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