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. 2007 Dec 28;190(5):1691–1698. doi: 10.1128/JB.01693-07

FIG. 1.

FIG. 1.

Transcriptional regulation by KaiC monitored by bioluminescence. (A) Genotype of the NUC0220 strain. In this strain, kaiBC is driven from the E. coli trc promoter (*) and can be induced by IPTG in a dose-dependent manner. (B and C) Initial responses (B) and subsequent profiles (C) of bioluminescence in NUC0220 after kaiBC induction at various concentrations of IPTG. Bioluminescence was analyzed in liquid culture under continuous light (LL) in the absence or presence of IPTG, administered at hour 0 (indicated by arrow) at the final concentrations as shown. The bioluminescence was plotted against the time after induction. The bioluminescence intensity before induction was normalized to 1. (D) Response of bioluminescence to the removal of IPTG in NUC0220. Cells were cultured in the presence of 100 μM IPTG for at least 36 h, washed, suspended in fresh medium lacking IPTG, and cultured under LL at 30°C. Bioluminescence was plotted against time after the removal of IPTG (indicated by the arrow). The maximum bioluminescence intensity was normalized to 1. All traces in this figure are representative of at least three replicates.