tailieunhanh - Báo cáo khoa học: Light-induced global structural changes in phytochrome A regulating photomorphogenesis in plants

Phytochromes are photoreceptor proteins that monitor the light environ-ment and regulate a variety of photomorphogenic responses to optimize the growth and development of plants. Phytochromes comprise N-terminal photosensory and C-terminal regulatory domains. They are mutually pho-toconvertible between a red-light-absorbing (Pr) and a far-red-light-absorb-ing (Pfr) form. Their interconversion by light stimuli initiates downstream signaling cascades. | ềFEBS Journal Light-induced global structural changes in phytochrome A regulating photomorphogenesis in plants Masayoshi Nakasako1 2 Tatsuya Iwata3 Katsuaki Inoue4 and Satoru Tokutomi3 1 Department of Physics Faculty of Science and Technology Keio University Kanagawa Japan 2 The RIKEN Harima Institute SPring-8 Hyogo Japan 3 The Research Institute for Advanced Science and Technology Osaka Prefecture University Japan 4 JASRI SPring-8 Hyogo Japan Keywords growth regulation light monitoring phytochrome A plants small-angle X-ray scattering Correspondence M. Nakasako Department of Physics Faculty of Science and Technology Keio University 3-14-1 Hiyoshi Kohoku-ku Kanagawa 223-8522 Japan Fax 81 45 566 1672 Tel 81 45 566 1679 E-mail nakasako@ or S. Tokutomi The Research Institute for Advanced Science and Technology Osaka Prefecture University 1-2 Gakuen-cho Sakai Osaka 599-8531 Japan Fax 81 72 254 9841 Tel 81 72 254 9841 E-mail toxan@ Received 7 October 2004 revised 25 November 2004 accepted 29 November 2004 Phytochromes are photoreceptor proteins that monitor the light environment and regulate a variety of photomorphogenic responses to optimize the growth and development of plants. Phytochromes comprise N-terminal photosensory and C-terminal regulatory domains. They are mutually photoconvertible between a red-light-absorbing Pr and a far-red-light-absorbing Pfr form. Their interconversion by light stimuli initiates downstream signaling cascades. Here we report the molecular structures of pea phytochrome A lacking the N-terminal 52 amino-acid residues in the Pr and Pfr forms studied by small-angle X-ray scattering. A new purification protocol yielded monodispersive sample solutions. The molecular mass and the maximum dimension of Pr determined from scattering data indicated its dimeric association. The molecular structure of Pr predicted by applying the ab initio simulation method to the scattering profile was approximated as a stack of