Fig. 4
From: A rapid and efficient strategy for combinatorial repression of multiple genes in Escherichia coli
The system exhibits leaky repression, which can be mitigated by using mutated sgRNA handle sequences. (A) The repression of rfp using sgRNA sequence expressed by the PlacO1 promoter with 0.5 mM IPTG. Control represents a strain that constitutively expresses fluorescent protein and does not contain CRISPRi; (B) The repression of rfp using sgRNA sequence expressed by the PLtetO−1 promoter with 4.3 µM of aTc; (C) The repression of rfp using sgRNA sequence expressed by the ParaBAD promoter with 13.3 mM of Ara. (D) Reduction of the leaky repression within the multi-gene combinatorial repression system. The lacZ1 spacer targeting the lacZ gene was used to characterize the background leakage of different sgRNA mutants. The red, yellow and blue circles indicate that the PlacO1, PLtetO−1 and ParaBAD promoters express sgRNA, respectively. The solid circle indicates the enzyme activity of lacZ when no inducer is added, and the hollow circle indicates the enzyme activity of lacZ when the corresponding inducer is added