Team:Kyoto/Project/GSDD

Genetic Expression Depending on Cell division

Fig.1

In biotechnology, genes in vectors soon express after transformation. We want the genes to express depending on the number of cell division after transformation. Ultimately, we want to make a system that can control freely the generation of genetic expression after transformation. If we can create a bacteria that cures human, and we inject it in human body, it has bad influence to human body that the artificial bacteria lives in human body forever. However, using in this system, we can create life span of bacteria if a gene that expresses in this system is cytorethal.

To achieve our purpose, our idea is using liner DNA as a vector that product repressor. Liner DNA is replicated incompletely because of the end replication problem. So, liner DNA becomes short by duplication. Through the repetition of duplication, Liner DNA becomes shorter and shorter, and ultimately the region of a gene becomes lost and the expression of the gene becomes silent. Product of repressor becomes silent and repression of a gene in the other plasmid vector becomes lost and the gene becomes expressed.

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Fig.2

The problem in this idea is that liner DNA is not stable in cell because of exonuclease　and proteins related to DNA repair. To settle this problem, the end of liner DNA is the repeats of specific protein binding sites. In this idea, specific proteins bind this repeats, and protect liner DNA by exonuclease , and proteins related to DNA repair. So,liner DNA becomes shorter and shorter, and when the repeats of specific protein binding sites are lost, exonuclease degrade liner DNA and production of repressor becomes silent. Now、we make a plan using E.coli and yeast. Figure 2 is the outline of this system in yeast. The proteins protecting the end of liner DNA is GAL4 in yeast, and LACI in E.coli.