This year, HUST-China designed a functional gene expression toolkit. The systems we designed can not only be adaptable to any input and output, but also be threshold-changable to meet the requirements of different project purposes.

Normally, gene expression level depends on the input signals' intensity but it always can't be strong enough, so it may be hard for former expression systems to deal with realistic problems.

Our toolkit can sense even pulse signal to reach its stable expression state and with validly characterized circuits, it will definitely help new iGEMers.


With the development of synthetic biology, we may need to construct more complex circuits which has increased difficulty and consumes a lot of time and energy. To know the problems iGEMers encounter when constructing circuits, we carried out a survey and the result showed that all participants had ever been bothered by gene expression problems, such as lack of robustness and expression leakage, etc. As real-world conditions are more complex than lab, there will be various factors to interrupt the input signal and gene expression. Thus, decreasing noise of signal input, or in other words, filtering the input signal to guarantee stable gene product expression has crucial practical significance and that’s where our signal filter shows its capability. Moreover, it serves as a toolkit of gene switch, freeing researchers of the worry about complicated circuits and helps them focus on the key problems.


We provide two versions of Signal Filter to meet different application requirements. The tri-stable circuit derived from bacteriaphage lambda can be applied in prokaryotic systems. Meanwhile,the bi-stable circuit adapted from ABA-response pathway in Arabidopsis thaliana is supposed to be used in eukaryotes. Following are brief introductions to our circuits:

Promoter RE can be activated by CII . Ftsh normally degrade CII, while CIII serves as an inhibitor of Ftsh to free CII. CI can function as an inhibitor to block pR, while Cro can block pRM. All of these parts and the interations between them can constitute three stable states and finally lead to different gene expressions.

When signal 1 (ON) comes, promoter rd29A drives expression of SnRK2.2, which can phosphorylate a large quantity of ABF2 in a short time by enzyme catalysis , then enhance Prd29A to turn on the gene of interest's expression. When signal 2 (OFF) comes, gene PP2CA expresses, dephosphorylates ABF2 and inactivates SnRK2.2, thus turning the system into OFF state.