Ribosome switch is used widely in synthetic biology to detect various small molecules. This summer, we chose an efficient ribosome switch created via a new method to detect atrazine [1]. And then, our team verified the basic parameters about this amazing ribosome switch, including the lowest detect concentration and the induced time.
Experiments and Results
Our team used this kind of ribosome switch which can detect atrazine to control the GFP expression in E.coli. E.coli expressed GFP after 20 hours under 500μM of atrazine, but could not express GFP without atrazine (Fig. 3-4-1). This shows the ribosome switch can be turned on under 500μM of atrazine.
Fig. 3-4-1 The ribosome switch exhibits conformations and function. (A) The principle of how the ribosome switch works. (B) Ribosome switch is induced by atrazine under 500μM of atrazine.
Our team used this part to control GFP expression in E.coli. We found all E.coli had expressed GFP under all the concentrations of atrazine, from 1μM to 500μM, in our experiment (Fig. 3-4-2). This data indicates that the ribosome switch can work under 1μM of atrazine.
Fig. 3-4-2 Various concentrations of atrazine were detected after 20h culturing. We detect the expression of GFP after the strain K-12 is cultured for 20h in the different concentrations from 1μM to 500μM.
Our team used this part to control the GFP expression in E.coli. We found E.coli had merely expressed GFP after 12 hours under 200μM of atrazine (Fig. 3-4-3).. This data elucidates that the ribosome switch can work after 12 hours under 200μM of atrazine.
Fig. 3-4-3 The ribosome switch was induced at different time under 200μM of atrazine. We detect the expression of GFP after that the strain K-12 is cultured under 200μM of atrazine at the different time from 6h to 12h.
According to these data, this ribosome switch is more efficient than the one used before.
However, for the reason of fluorescence quenching, the fluorescence intensity would descending for too high concentration of GFP. So we detected the RFU changing with time and atrazine’s concentration and identified the range of concentration of atrazine (Fig. 3-4-4). Therefore, we are confident of the fact that we can put this amazing part into detecting atrazine in real life.
Fig. 3-4-4 The RFU changing with time and atrazine’s concentration.
Reference
[1] Sinha J, et al. Reprogramming bacteria to seek and destroy a herbicide. Nature chemical biology, 2010, 6 (6): 464-470.
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