title: Light-induced conformational changes in full-length Arabidopsis thaliana cryptochrome.
abstract: Cryptochromes (CRYs) are widespread flavoproteins with homology to photolyases (PHRs), a class of blue-light-activated DNA repair enzymes. Unlike PHRs, both plant and animal CRYs have a C-terminal domain. This cryptochrome C-terminal (CCT) domain mediates interactions with other proteins, while the PHR-like domain converts light energy into a signal via reduction and radical formation of the flavin adenine dinucleotide cofactor. However, the mechanism by which the PHR-like domain regulates the CCT domain is not known. Here, we applied the pulsed-laser-induced transient grating method to detect conformational changes induced by blue-light excitation of full-length Arabidopsis thaliana cryptochrome 1 (AtCRY1). A significant reduction in the diffusion coefficient of AtCRY1 was observed upon photoexcitation, indicating that a large conformational change occurs in this monomeric protein. AtCRY1 containing a single mutation (W324F) that abolishes an intra-protein electron transfer cascade did not exhibit this conformational change. Moreover, the conformational change was much reduced in protein lacking the CCT domain. Thus, we conclude that the observed large conformational changes triggered by light excitation of the PHR-like domain result from C-terminal domain rearrangement. This inter-domain modulation would be critical for CRYs' ability to transduce a blue-light signal into altered protein-protein interactions for biological activity. Lastly, we demonstrate that the transient grating technique provides a powerful method for the direct observation and understanding of photoreceptor dynamics.
authors.affiliation: Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Kondoh
authors.forename: Chiaki
authors.initials: C
authors.lastname: Shiraishi
authors.forename: Pavel
authors.initials: P
authors.lastname: Müller
authors.forename: Margaret
authors.initials: M
authors.lastname: Ahmad
authors.forename: Kenichi
authors.initials: K
authors.lastname: Hitomi
authors.forename: Elizabeth D
authors.initials: ED
authors.lastname: Getzoff
authors.forename: Masahide
authors.initials: M
authors.lastname: Terazima
mesh_terms: D019943:Amino Acid Substitution / Q000235:genetics; D017360:Arabidopsis / Q000737:chemistry* / Q000235:genetics / Q000528:radiation effects*; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000235:genetics / Q000528:radiation effects*; D056931:Cryptochromes / Q000737:chemistry* / Q000235:genetics / Q000528:radiation effects*; D008027:Light; D008954:Models, Biological; D008956:Models, Chemical; D050505:Mutant Proteins / Q000737:chemistry / Q000235:genetics / Q000528:radiation effects; D011487:Protein Conformation / Q000528:radiation effects
chemical_list: D029681:Arabidopsis Proteins; C538962:CRY1 protein, Arabidopsis; D056931:Cryptochromes; D050505:Mutant Proteins