Fig. 2. iLight-based system for the light-induced repression of protein expression in bacteria.

a, b Dependence of the inhibition efficiency on the duration of (a) Off and (b) On time of the 660 nm illumination. c Effect of 780 nm light, which photoconverts iLight from the Pfr state to the Pr state, on the inhibition of the mCherry reporter production. Box plots show the median (center line), first and third quartiles (box edges), 1× the SD (whiskers), and individual data points. The illumination steps described in a–c were repeated in the loop and the total duration of each of these experiments was 16 h. d Inhibition of the mCherry reporter expression in the ongoing mCherry expression conditions. Bacterial samples expressing the mCherry reporter were cultured in darkness and then transferred to 660 nm light for the indicated illumination time periods, after which the fluorescence intensity of the bacteria was analyzed. Each bacterial sample was cultured for total 24 h before the analysis. Error bars, SD (n = 4 independent experiments). e Efficiency of the inhibition of the mCherry reporter production by various single-point mutants of iLight. Error bars, SD (n = 4 independent experiments). In a–d, a.u., arbitrary units. Source Data are available as a Source Data file.