Flavin-based blue-light photosensors: A photobiophysics update

This review deals with the biophysical aspects of flavin-based photosensors, comprising cryptochromes, LOV (Light, Oxygen and Voltage) and BLUF (Blue Light sensing Using FAD) proteins. Special emphasis is given to structural issues, photo-cycle quantum yields and energetics, mechanism of the light-triggered reactions, early stages in signal transduction and oligomeric states of the light sensing protein modules. For BLUF and LOV domains important parallels are emerging, despite their different alpha/beta fold arrangement, whereas there is increasing evidence for a mechanicistic and functional splitting of the cryptochrome family.