Difference between revisions of "Part:BBa K518010"

Revision as of 08:40, 25 October 2020

sulA promoter

Microbes including Escherichia coli are known to respond to various DNA-injuring stress (ionizing radiation, ultraviolet radiation, peroxides etc...), altering their gene expression patterns. This response, known as the "SOS response", is induced by a regulatory protein called RecA when it binds to single-strand DNA. The DNA-RecA complex promotes the degradation of LexA, a common repressor of SOS genes.

SulA is responsible for stress-induced halt of cell division. The promoter of sulA, sulAp, is induced by various stress factors, including ultraviolet irradiation.

Application

We utilized this property (induced-expression by UV irradiation) to design a "UV switch". This makes it possible to "switch on" a genetic circuit using UV. As a first step for this, we characterized the UV-induction of sulAp.

The UV-induced expression level of BBa_K518010 was evaluated using BBa_K518013. As a measurement tool, our dual luciferase assay kit was employed. For detailed infomation, see BBa_K518002.

<Figure: UV-induced expression levels of sulAp. The expression levels from sulAp were evaluated before and after UV induction. We evaluated it using both recA(-) (JM109) and recA(+) (BL21) strain. RecA is known to be necessary for releasing sulAp from repression. We successfully demonstrated a significant alteration of expression in recA(+) strain only after UV irradiation. The expression level of BBa_J23119, a constitutive E. coli promoter which is often used as a comparison, was simultaneously presented. Data is expressed as mean ± S.D.. Data is obtained from the average of three independent experiments.>

Team: 2020 SZ-SHD: Investigated the UV-induction time to the expression level of SulAp:

In our project, experiments have been carried out to measure the expression level of eGFP gene behind SulAp promoter in BL21, with different exposure time under UV induction.

Figure: the result of eGFP expression after irradiated under UVC, unit: fluorescence per OD. eGFP- UV+: non-recombinant BL21 irradiated under UVC (without pSS1); eGFP- UV-: non-recombined BL21 without UV exposure. 0min: recombined BL21, no UV exposure; 0.5min: recombined BL21 irradiated under UV for 30 seconds; 1min: irradiated under UV for 1 min; 2min: irradiated under UV for 2 min.

Sequence and Features