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==Crystal structure of UVB photoreceptor UVR8 from Arabidopsis thaliana and UV-induced structural changes at 120K==
<StructureSection load='4naa' size='340' side='right'caption='[[4naa]], [[Resolution|resolution]] 1.67&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[4naa]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Arabidopsis_thaliana Arabidopsis thaliana]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4NAA OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4NAA FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 1.67&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=4naa FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4naa OCA], [https://pdbe.org/4naa PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4naa RCSB], [https://www.ebi.ac.uk/pdbsum/4naa PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4naa ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/UVR8_ARATH UVR8_ARATH] UV-B specific signaling component that acts as UV-B photoreceptor and plays a key role in establishing UV-protective responses in plants. Upon UV-B irradiation, UVR8 undergoes an immediate switch from homodimer to monomer, accumulates in the nucleus, interacts with the photomorphogenic repressor COP1 and regulates the expression of the transcription factor HY5 by associating with chromatin (through histone H2B binding) in the HY5 promoter region. UVR8 is involved in controlling aspects of leaf growth and morphogenesis in response to UV-B, is required for normal progression of endocycle and has a regulatory role in stomatal differentiation. Is required for plant circadian clock response to photomorphogenic UV-B light, partly through the transcriptional activation of responsive clock genes. Promotes photosynthetic efficiency at elevated levels of UV-B. Plays a role in mediating the effects of UV-B radiation on pathogen resistance by controlling the expression of the sinapate biosynthetic pathway. The two tryptophans, Trp-285 and Trp-233, serve collectively as the UV-B chromophore.<ref>PMID:16330762</ref> <ref>PMID:17720867</ref> <ref>PMID:18055587</ref> <ref>PMID:19165148</ref> <ref>PMID:19402876</ref> <ref>PMID:21041653</ref> <ref>PMID:21395889</ref> <ref>PMID:21454788</ref> <ref>PMID:22447155</ref> <ref>PMID:23161229</ref> <ref>PMID:23012433</ref> <ref>PMID:22988111</ref> 
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== Publication Abstract from PubMed ==
Arabidopsis thaliana UVR8 (AtUVR8) is a long-sought-after photoreceptor that undergoes dimer dissociation in response to UV-B light. Crystallographic and mutational studies have identified two crucial tryptophan residues for UV-B responses in AtUVR8. However, the mechanism of UV-B perception and structural events leading up to dimer dissociation remain elusive at the molecular level. We applied dynamic crystallography to capture light-induced structural events in photoactive AtUVR8 crystals. Here we report two intermediate structures at 1.67A resolution. At the epicenter of UV-B signaling, concerted motions associated with Trp285/Trp233 lead to ejection of a water molecule, which weakens an intricate network of hydrogen bonds and salt bridges at the dimer interface. Partial opening of the beta-propeller structure due to thermal relaxation of conformational strains originating in the epicenter further disrupts the dimer interface and leads to dimer dissociation. These dynamic crystallographic observations provide structural insights into the photo-perception and signaling mechanism of UVR8.

Dynamic Crystallography Reveals Early Signalling Events in Ultraviolet Photoreceptor UVR8.,Zeng X, Ren Z, Wu Q, Fan J, Peng PP, Tang K, Zhang R, Zhao KH, Yang X Nat Plants. 2015;1. pii: 14006. PMID:26097745<ref>PMID:26097745</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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<div class="pdbe-citations 4naa" style="background-color:#fffaf0;"></div>
== References ==
<references/>
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</StructureSection>
[[Category: Arabidopsis thaliana]]
[[Category: Large Structures]]
[[Category: Ren Z]]
[[Category: Yang X]]
[[Category: Zeng X]]
[[Category: Zhao KH]]