Photometrical analysis with photosensory domains of photoreceptors in green algae

Chloroplast photoorientation in the green alga Mougeotia scalaris is controlled by blue and red light. The properties of the LOV domains of phototropin A and B were consistent with previous data of action spectra and photoreceptor lifetime for blue light-mediated photoorientation. The LOV domains of the neochromes did not bind flavin, while the domains of neochrome 2 contributed to multimer formation. The absorption spectra of the neochrome phytochrome photosensory domain with phytochromobilin were very similar to the action spectra for red light-induced photoorientation. These results indicate that phototropin and neochrome work as the blue and red photoreceptors involved in photoorientation.