title: Structural basis of a phototropin light switch.
abstract: Phototropins are light-activated kinases important for plant responses to blue light. Light initiates signaling in these proteins by generating a covalent protein-flavin mononucleotide (FMN) adduct within sensory Per-ARNT-Sim (PAS) domains. We characterized the light-dependent changes of a phototropin PAS domain by solution nuclear magnetic resonance spectroscopy and found that an alpha helix located outside the canonical domain plays a key role in this activation process. Although this helix associates with the PAS core in the dark, photoinduced changes in the domain structure disrupt this interaction. We propose that this mechanism couples light-dependent bond formation to kinase activation and identifies a signaling pathway conserved among PAS domains.
authors.affiliation: Departments of Biochemistry and Pharmacology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9038, USA.
authors.forename: Shannon M
authors.initials: SM
authors.lastname: Harper
authors.forename: Lori C
authors.initials: LC
authors.lastname: Neil
authors.forename: Kevin H
authors.initials: KH
authors.lastname: Gardner
mesh_terms: D000595:Amino Acid Sequence; D018554:Avena / Q000737:chemistry*; D056931:Cryptochromes; D003624:Darkness; D029721:Drosophila Proteins; D005136:Eye Proteins; D005420:Flavoproteins / Q000737:chemistry* / Q000378:metabolism; D008027:Light; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D017956:Photoreceptor Cells, Invertebrate; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D043562:Receptors, G-Protein-Coupled; D015398:Signal Transduction
chemical_list: D056931:Cryptochromes; D029721:Drosophila Proteins; D005136:Eye Proteins; D005420:Flavoproteins; D043562:Receptors, G-Protein-Coupled; C119828:cry protein, Drosophila