Part:BBa_K2615018
MiniToe polycistron A: a new system using miniToe.
Background of 2018 OUC-China' project——miniToe family
This year, we design a toolkit named miniToe family focused on translational regulation, which is composed of a RNA endoribonuclease (Csy4) and a RNA module (hairpin). In our project, the cleavage function of Csy4 releases a cis-repressive RNA module (crRNA, paired with RBS) from the masked ribosome binding site (RBS), which subsequently allows the downstream translation initiation. A Ribosome Binding Site (RBS) is an RNA sequence to which ribosomes can bind and initiate translation.
We design miniToe family to meet the aim, "One system, diverse expression". This means by using one system we can even achieve flexable expression of target gene. So we further design four Csy4 mutants by point mutation( Csy4-Y176F, Csy4-H29A, Csy4-F155A, Csy4-Q104A). At the same time, we redesign 5 different hairpin mutants named miniToe(5 different types of Csy4 recognition sequence) which can be recognized and cleaved by Csy4 mutants. ( miniToe-1, miniToe-2, miniToe-3, miniToe-4, miniToe-5, miniToe-WT).
miniToe polycistron
Having designed different hairpin structures and finished experimental verification, we think it is a good idea to apply it to the polycistronic to achieve more functions by using miniToe. The polycistronic structure can meet the requirements of simultaneous and large-scale expression of different genes. We insert the hairpin structure(miniToe) into the polycistron and apply the interaction between the hairpin structure and the Csy4 enzyme to achieve the regulation of different ratio of multiple gene expression levels, meeting the requirements of practical application.
From now, we construct two polycistron(miniToe polycistron A and miniToe polycistron B) by inserting three miniToes before, between and behind two CDS. We use miniToe-WT(BBa_K2615020) before and behind miniToe polycistron A(BBa_K2615018), meanwhile the miniToe-5(BBa_K2615025) is used between two CDS. And we use sfGFP and mCherry to test our system. The result shows we can totally change the origin ratio of two genes.
Result
The purpose of experiment
The miniToe polycistron is a new method designed by OUC-China this year. By inserting miniToe hairpins between intergenetic regions, it will tune the translation level of corresponding proteins.
1)First, sfGFP and mCherry is used as a test system in bi-cistron circuit.
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2)Then we selected some miniToe parts and inserted them between, before and behind sfGFP and mCherry. For example, for bi-cistron, then three miniToe parts will be inserted. for three genes in polycistron, then four miniToe parts will be inserted, and so on.
This year, we have two kinds of miniToe polycistron, miniToe polycistron-A and miniToe polycistron-B. In the future, we will test more miniToe polycistron based on miniToe family.
Proof of functions
The result by microplate reader has been shown in the Fig.4. After culturing for 10 hours, the rate of fluorescence intensities by sfGFP/mCherry was changed by miniToe family. The group A is a control group whose circuits have no miniToe part. The ratio of fluorescence intensities by sfGFP/mCherry is about 6.81 which means the gene near the promoter has much higher expression than the gene far from promoter in a normal polycistron. The test group-polycistron A has been changed by miniToe system because the ratio of fluorescence intensities decrease to 4.38. To our surprise, the test group-polycistron B shows the significant change whose rate is about 2.82. It means the ratio of gene expression can be regulated by miniToe family. In the future, the miniToe family create more possibilities in regulating the ratio of gene expression.
Sequence and Features
- 10COMPATIBLE WITH RFC[10]
- 12INCOMPATIBLE WITH RFC[12]Illegal NheI site found at 13
Illegal NheI site found at 36 - 21INCOMPATIBLE WITH RFC[21]Illegal BglII site found at 1
- 23COMPATIBLE WITH RFC[23]
- 25COMPATIBLE WITH RFC[25]
- 1000INCOMPATIBLE WITH RFC[1000]Illegal SapI.rc site found at 197
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