N- and C-terminal helices of oat LOV2 (404-546) are involved in light-induced signal transduction (room temperature (293K) dark structure of LOV2 (404-546))
N- and C-Terminal Flanking Regions Modulate Light-Induced Signal Transduction in the Lov2 Domain of the Blue Light Sensor Phototropin 1 from Avena Sativa.
Light sensing by photoreceptors controls phototropism, chloroplast movement, stomatal opening, and leaf expansion in plants. Understanding the molecular mechanism by which these processes are regulated requires a quantitative description of photoreceptor dynamics ...
Light sensing by photoreceptors controls phototropism, chloroplast movement, stomatal opening, and leaf expansion in plants. Understanding the molecular mechanism by which these processes are regulated requires a quantitative description of photoreceptor dynamics. We focus on a light-driven signal transduction mechanism in the LOV2 domain (LOV, light, oxygen, voltage) of the blue light photoreceptor phototropin 1 from Avena sativa (oat). High-resolution crystal structures of the dark and light states of an oat LOV2 construct including residues Leu404 through Leu546 (LOV2 (404-546)) have been determined at 105 and 293 K. In all four structures, LOV2 (404-546) exhibits the typical Per-ARNT-Sim (PAS) fold, flanked by an additional conserved N-terminal turn-helix-turn motif and a C-terminal flanking region containing an amphipathic Jalpha helix. These regions dock on the LOV2 core domain and bury several hydrophobic residues of the central beta-sheet of the core domain that would otherwise be exposed to solvent. Light structures of LOV2 (404-546) reveal that formation of the covalent bond between Cys450 and the C4a atom of the flavin mononucleotide (FMN) results in local rearrangement of the hydrogen-bonding network in the FMN binding pocket. These rearrangements are associated with disruption of the Asn414-Asp515 hydrogen bond on the surface of the protein and displacement of the N- and C-terminal flanking regions of LOV2 (404-546), both of which constitute a structural signal.
Organizational Affiliation:
Department of Biochemistry and Molecular Biology, The University of Chicago, 929 East 57th Street, Chicago, Illinois 60637, USA.
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