Team:Paris Bettencourt/Project/Phage Sensor
From 2013.igem.org
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Overview
We develop a sensor to target antibiotic resistances in tuberculosis to test if a specific strain carries a certain antibiotic resistance. Our sensor system consists out of a phagemid with a CRISPR/Cas system and LacZ as a reporter under the control of a pREC promoter (the promoter of the RecA protein that is involved in the stress response of bacteria). If our CRISPR/Cas system can now bind to the target (antibiotic resistance gene), the Cas9 generates at this specific target site a double strand break, which then starts the expression of our reporter, as the promoter gets active at stress that results from double strand breaks. Because our system is on a phagemid, the sensor system will be spread all over the population, which will give a clear color output if the target has been detected. This means, depending on what target sequence our system carries, we can identify the different antibiotic resistances that a strain might carry. This is a novel way of detecting resistances in bacterial strains. As a proof of concept we will use E.coli to target KanR. The used phage will be M13. This sensor could potentially be used to test if a patient has TB and what type of resistance genes the specific strain contains to adapt drug treatment.
Producer bacteria
Phagemid is packed into the capsid, produced by the helper plasmid
Phagmids are isolated
Phagmids are mixed with target bacteria
Right species?
Yes, Phagemids enter the cell
Expression of CrRNA, tracerRNA and Cas9
Processing of CrRNA + tracerRNA
Fusion of Cas9 and hybrid RNA complex
Antibiotic resistance of interest there?
Yes : Cas9 - RNA complex bind to target sequence
Cas9 generates double strand break
pRech-SOS response activated
LacZ is expressed
ß-galactosidase hydrolisis Xgal : blue cells appear