Why do we want to do the program of engineering bacteria ?About Design
Our basic engineered bacteria design consists of 2 components, E. coli and lactobacillus. The overall response of this system mainly including 3 parts.
In part 1, lactobacillus would constitutively reduce AHL, which is a kind of quorum sensing molecule of E. coli through LuxI (AHL synthase)1. And a chloride-induced expression system is employed to trigger the lysis of lactobacillus and release AHL2.
In part 2, engineered E. coli would sense the released AHL through EsaR protein. EsaR protein is constitutively expressed and it could bind to Esa box in the absence of AHL molecules, and inhibit downstream expression3-5. In the presence of AHL, the inhibitory effect of AHL is destroyed and downstream water storage polysaccharides expression is activated. Therefore, we can realize the specific expression of polysaccharides to achieve the purpose of storing water and preventing dehydration.
In part 3, upon the presence of AHL, engineered E. coli would secrete antibacterial peptides with an additional trigger – quorum sensing molecules of the specific pathogens. For instance, here we target the V. cholera and introduce the V. cholera quorum sensing system in E. coli based on the work of Maciej B et al6,7. Under the existence of CAI-1 (quorum sensing molecule of V. cholera), our designed system would promote the downstream antibacterial peptides expression with a help of PhlF inverter system8. Finally, we can achieve the purpose of secreting antibacterial substances to kill pathogenic bacteria.
For more details of our design, please refer to the contents in our engineering part. It is worth noting that the division of part here is slightly different from that of the modeling and experimental parts.
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