DsLOV domain architecture and photochemistry. (A) Domain architecture of the three D. shibae LOV proteins. Locus tags and accession numbers (in brackets) are given in front of each protein. The length of each protein and the type and relative location of all predicted Pfam domains are specified. LOV: light, oxygen voltage; HK: histidine kinase; PAS: PER-ARNT-SIM; RR: response regulator. (B) Absorbance spectra of DsLOV in the dark and light state. In the dark, DsLOV displays the characteristic UV/vis absorbance bands with a λmax of about 449 nm (solid line). To sufficiently populate the light state, the DsLOV protein was exposed to blue-light for 30 seconds at 4°C (dashed lines), resulting in a decreased absorbance at 447 nm and the concomitant formation of a new absorbance maximum at 390 nm. The inset shows the light–dark difference spectrum of DsLOV. (C) Dark recovery of DsLOV measured at 20°C. LOV protein dark recovery was monitored by recording time traces for the absorbance recovery at 485 nm after blue-light illumination. The data (squares) was fitted using a mono-exponential decay function.