8a4e | pdb_00008a4e
Room temperature structure of AtPhot2LOV2 in a photostationary equilibrium
Structural highlights
FunctionPHOT2_ARATH Protein kinase that acts as a blue light photoreceptor in a signal-transduction pathway for photo-induced movements. Mediates calcium spiking of extra- and intracellular origins in response to blue light. Involved in hypocotyl phototropism. Contributes to the chloroplast accumulation in low blue light and mediates their translocation (avoidance response) at high fluence. Regulates stomata opening and photomorphogenesis response of leaf tissue. Not involved in hypocotyl elongation inhibition, anthocyanin accumulation or cotyledon opening.[1] [2] [3] [4] [5] Publication Abstract from PubMedThe development of serial crystallography over the last decade at XFELs and synchrotrons has produced a renaissance in room-temperature macromolecular crystallography (RT-MX), and fostered many technical and methodological breakthroughs designed to study phenomena occurring in proteins on the picosecond-to-second timescale. However, there are components of protein dynamics that occur in much slower regimes, of which the study could readily benefit from state-of-the-art RT-MX. Here, the room-temperature structural study of the relaxation of a reaction intermediate at a synchrotron, exploiting a handful of single crystals, is described. The intermediate in question is formed in microseconds during the photoreaction of the LOV2 domain of phototropin 2 from Arabidopsis thaliana, which then decays in minutes. This work monitored its relaxation in the dark using a fast-readout EIGER X 4M detector to record several complete oscillation X-ray diffraction datasets, each of 1.2 s total exposure time, at different time points in the relaxation process. Coupled with in crystallo UV-Vis absorption spectroscopy, this RT-MX approach allowed the authors to follow the relaxation of the photoadduct, a thio-ether covalent bond between the chromophore and a cysteine residue. Unexpectedly, the return of the chromophore to its spectroscopic ground state is followed by medium-scale protein rearrangements that trigger a crystal phase transition and hinder the full recovery of the structural ground state of the protein. In addition to suggesting a hitherto unexpected role of a conserved tryptophan residue in the regulation of the photocycle of LOV2, this work provides a basis for performing routine time-resolved protein crystallography experiments at synchrotrons for phenomena occurring on the second-to-hour timescale. Slow protein dynamics probed by time-resolved oscillation crystallography at room temperature.,Aumonier S, Engilberge S, Caramello N, von Stetten D, Gotthard G, Leonard GA, Mueller-Dieckmann C, Royant A IUCrJ. 2022 Sep 28;9(Pt 6):756-767. doi: 10.1107/S2052252522009150. eCollection , 2022 Nov 1. PMID:36381146[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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