Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.07.30.227371v1?rss=1 Authors: Palayam, M., Ganapathy, J., Guercio, A. M., Tal, L., Deck, S. L., Shabek, N. Abstract: Cryptochromes (CRYs) are evolutionarily conserved blue-light receptors that mediate various light-induced responses in bacteria, plants, and animals. Plant cryptochromes govern a variety of critical growth and developmental processes including seed germination, flowering time and entrainment of the circadian clock. CRYs photocycle involves reduction of their flavin adenine dinucleotide (FAD)-bound chromophore, which is completely oxidized in the dark and semi-reduced in the light signalling-active state. Despite the significant progress in characterizing cryptochromes, important aspects of their photochemistry, regulation, and light-induced structural adaptation remain to be addressed. In this study, we determine the crystal structure of the photosensory domain of Arabidopsis CRY2 in a tetrameric active state. Systematic structure-based analyses of photo-activated and inactive plant CRYs elucidate new structural elements and critical residues that dynamically partake in photo-induced oligomerization. Our study offers an updated model of CRYs photoactivation mechanism as well as the mode of its regulation by interacting proteins. Copy rights belong to original authors. Visit the link for more info