Programmable synthetic pathway fine-tuned by inverting promoter

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Soo-in Lee, Dong-Hee Choe, Yoseb Song, Suhyung Cho, Byung-Kwan Cho

South Korea

Since synthetic biology has been emerged, biological research which just studied about how to enhance cell’s productivity has shifted its paradigm toward re-programming of organism considering physiology and systems of the cell. With this trend, circuit systems such as logic gates, genetic toggle switches and oscillators has been embodied in cellular system to control metabolic pathways or regulatory networks. However, many of these systems work in irreversible manner. To construct a programmable reversible synthetic pathway system, we designed a promoter positioned between attB and attP sequences, the specific binding sites of Mycobacterium phage Bxb1 integrase/excisionase, which can be inverted by gene recombination mechanism. This invertible promoter flanked by synthetic pathways can initiate their transcription selectively according to the level of cellular signal. In this research, bio-indigo pathway which is operated by bacterial flavin-containing monooxygenase(bFMO) was a target synthetic pathway and quorum-sensing system was adopted as an indicator of level of metabolites. We demonstrated that bio-indigo pathway can be ON and OFF according to the amount of quorum-sensing molecules, respectively. This programmable synthetic pathway system provides an efficient platform tool needed to advance fine-tuned controllable metabolic processes for industrial applications. [This work was supported by the Intelligent Synthetic Biology Center of Global Frontier Project funded by the Ministry of Education, Science and Technology (2011-0031957).]