Difference between revisions of "Part:BBa K2969000"

Latest revision as of 17:50, 19 October 2019

TEV protease

TEV protease is a highly specific cysteine protease from Tobacco Etch Virus that recognizes the amino-acid sequence Glu-Asn-Leu-Tyr-Phe-Gln-(Gly/Ser) and cleaves between the Gln and Gly/Ser residues. It is often used for the removal of affinity purification tags such as maltose-binding protein (MBP) or poly-histidine from fusion proteins. In our project we insert the recognition sequence into the transcription factors so that the expression of protease can inhibit the action of transcription factors.

Characterization

We inserted the TEV protease recognition sequence between N-terminal and C-terminal of CI434 so that it can be cleaved by TEV and then lose activity. We put the reporter gene sf-GFP under the promoter of CI434 so that when TEV protease cleaves CI434, the expression of sf-GFP will rise. We use pTac to regulate the expression of TEV protease. Induced by different concentrations of IPTG, we get the cleavage effciency of TEV protease through the fluorecence of sf-GFP.

Figure 2:The cleavage efficiency of TEV to CI434-TEVsite induced by a series of concentrations of IPTG

In UCAS-China 2019 project, TEV protease is an important part of our switches. According to resent research, we can find many similar proteases to build similar cold-inducible switches such as TVMV protease (cleavage site TVRFQS), SuMMV protease (cleavage site EEIHLQ), HRV3C (cleavage site LEVLFQGP).

To realize the function of sequence switches, we combine the two different cold-inducible switches. However, we should make sure that these two combinations have no influence on each other. Thus, we design experiments to verify the orthogonality of different cold-inducible switch. That is the orthogonality of different proteases and their cleavage sites. We insert all the four cleavage sites into the transcription factor CI434 to build the relation between protease and transcription factor. Then we transform all the 16 kinds of combination of protease and CI434 into E.coli using sf-gfp as the reporter gene (GOI). Only the right pair can erase the inhibition of CI434 and trigger the expression of sf-gfp. Through the results of the fluorescence expression, we can find whether there are interactions between one protease and one cleavage site. The results below demonstrate good orthogonality between these proteases and their cleavage sites.

Figure 1:the orthogonality among four proteases represented by the fluorescence of sf-gfp is shown.

Reference

Voigt, C. A. and Fernandez-Rodriguez, J. , Post-translational control of genetic circuits using Potyvirus proteases Jesus, 2016, 44(13): 6493-6502

Sequence and Features