Chromatic response of CcaS-CcaR system variants in <i>E</i>. <i>coli</i>.

(A) Chromophore-dependent photoswitching behavior of the CcaS-CcaR system in E. coli with PCB and PΦB with unmodified CcaS and CcaR proteins. System output in response to light stimuli was quantified via sfGFP fluorescence and presented as RFUs; RFUs are defined as the mean estimated sfGFP fluorescence from cell cultures with OD600 nm = 0.2. Bacterial cultures were exposed to light stimuli (approximately 10 μmol m-2 s-1) generated using LEDs with peak wavelength emissions around 400 nm, 455 nm, 525 nm, 590 nm, 605 nm, 630 nm, 660 nm, and 695 nm. (B) System responses for CcaS(A92V) and CcaSHL co-produced with PΦB. Symbols are colored according to light treatment and depict mean fluorescence from 3 replicate experiments, each comprising 3 biological replicates for each light treatment. SEM are presented for each light treatment. The underlying data for panels A and B is in S1 Data. LED, light-emitting diode; PCB, phycocyanobilin; RFU, relative fluorescence unit; sfGFP, superfolder green fluorescent protein.