View source for 6qtt


==Crystal structure of an Arabidopsis WD40 domain in complex with a transcription factor homolog==
<StructureSection load='6qtt' size='340' side='right'caption='[[6qtt]], [[Resolution|resolution]] 1.51&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[6qtt]] is a 2 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=6QTT OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=6QTT 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]] 1.51&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=ACE:ACETYL+GROUP'>ACE</scene>, <scene name='pdbligand=CSO:S-HYDROXYCYSTEINE'>CSO</scene>, <scene name='pdbligand=GOL:GLYCEROL'>GOL</scene>, <scene name='pdbligand=MLI:MALONATE+ION'>MLI</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=6qtt FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6qtt OCA], [https://pdbe.org/6qtt PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=6qtt RCSB], [https://www.ebi.ac.uk/pdbsum/6qtt PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=6qtt ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/COP1_ARATH COP1_ARATH] E3 ubiquitin-protein ligase that acts as a repressor of photomorphogenesis and as an activator of etiolation in darkness. E3 ubiquitin ligases accept ubiquitin from an E2 ubiquitin-conjugating enzyme in the form of a thioester and then directly transfers the ubiquitin to targeted substrates. Represses photomorphogenesis in darkness by mediating ubiquitination and subsequent proteasomal degradation of light-induced transcription factors such as HY5, HYH and LAF1. Down-regulates MYB21, probably via ubiquitination process. Light stimuli abrogate the repression of photomorphogenesis, possibly due to its localization to the cytoplasm. Could play a role in switching between skotomorphogenetic and photomorphogenetic pathways.<ref>PMID:11967090</ref> <ref>PMID:12023303</ref> 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Plants sense different parts of the sun's light spectrum using distinct photoreceptors, which signal through the E3 ubiquitin ligase COP1. Here, we analyze why many COP1-interacting transcription factors and photoreceptors harbor sequence-divergent Val-Pro (VP) motifs that bind COP1 with different binding affinities. Crystal structures of the VP motifs of the UV-B photoreceptor UVR8 and the transcription factor HY5 in complex with COP1, quantitative binding assays, and reverse genetic experiments together suggest that UVR8 and HY5 compete for COP1. Photoactivation of UVR8 leads to high-affinity cooperative binding of its VP motif and its photosensing core to COP1, preventing COP1 binding to its substrate HY5. UVR8-VP motif chimeras suggest that UV-B signaling specificity resides in the UVR8 photoreceptor core. Different COP1-VP peptide motif complexes highlight sequence fingerprints required for COP1 targeting. The blue-light photoreceptors CRY1 and CRY2 also compete with transcription factors for COP1 binding using similar VP motifs. Thus, our work reveals that different photoreceptors and their signaling components compete for COP1 via a conserved mechanism to control different light signaling cascades.

Plant photoreceptors and their signaling components compete for COP1 binding via VP peptide motifs.,Lau K, Podolec R, Chappuis R, Ulm R, Hothorn M EMBO J. 2019 Sep 16;38(18):e102140. doi: 10.15252/embj.2019102140. Epub 2019 Jul , 15. PMID:31304983<ref>PMID:31304983</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 6qtt" style="background-color:#fffaf0;"></div>

==See Also==
*[[Ubiquitin protein ligase 3D structures|Ubiquitin protein ligase 3D structures]]
== References ==
<references/>
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</StructureSection>
[[Category: Arabidopsis thaliana]]
[[Category: Large Structures]]
[[Category: Hothorn M]]
[[Category: Lau K]]