View source for 8ime


==Human cGAS catalytic domain bound with baicalin==
<StructureSection load='8ime' size='340' side='right'caption='[[8ime]], [[Resolution|resolution]] 2.63&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[8ime]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=8IME OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=8IME 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]] 2.63&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=0XE:5,6-DIHYDROXY-4-OXO-2-PHENYL-4H-CHROMEN-7-YL+BETA-D-GLUCOPYRANOSIDURONIC+ACID'>0XE</scene>, <scene name='pdbligand=ZN:ZINC+ION'>ZN</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=8ime FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=8ime OCA], [https://pdbe.org/8ime PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=8ime RCSB], [https://www.ebi.ac.uk/pdbsum/8ime PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=8ime ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/CGAS_HUMAN CGAS_HUMAN] Nucleotidyltransferase that catalyzes formation of cyclic GMP-AMP (cGAMP) from ATP and GTP and exhibits antiviral activity. Has antiviral activity by acting as a key cytosolic DNA sensor, the presence of DNA in the cytoplasm being a danger signal that triggers the immune responses. Binds cytosolic DNA directly, leading to activation and synthesis of cGAMP, a second messenger that binds to and activates TMEM173/STING, thereby triggering type-I interferon production.<ref>PMID:21478870</ref> <ref>PMID:23258413</ref> 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Cyclic GMP-AMP synthase (cGAS) plays an important role in the inflammatory response. It has been reported that aberrant activation of cGAS is associated with a variety of immune-mediated inflammatory disorders. The development of small molecule inhibitors of cGAS has been considered as a promising therapeutic strategy for the diseases. Flavonoids, a typical class of natural products, are known for their anti-inflammatory activities. Although cGAS is closely associated with inflammation, the potential effects of natural flavonoid compounds on cGAS have been rarely studied. Therefore, we screened an in-house natural flavonoid library by pyrophosphatase (PP(i)ase) coupling assay and identified novel cGAS inhibitors baicalein and baicalin. Subsequently, crystal structures of the two natural flavonoids in complex with human cGAS were determined, which provide mechanistic insight into the anti-inflammatory activities of baicalein and baicalin at the molecular level. After that, a virtual screening based on the crystal structures of baicalein and baicalin in complex with human cGAS was performed. As a result, compound C20 was identified to inhibit both human and mouse cGAS with IC(50) values of 2.28 and 1.44 muM, respectively, and its detailed interactions with human cGAS were further revealed by the X-ray crystal structure determination. These results demonstrate the potential of natural products used as hits in drug discovery and provide valuable hints for further development of cGAS inhibitors.

Discovery of novel cGAS inhibitors based on natural flavonoids.,Li J, Xiong M, Liu J, Zhang F, Li M, Zhao W, Xu Y Bioorg Chem. 2023 Nov;140:106802. doi: 10.1016/j.bioorg.2023.106802. Epub 2023 , Aug 22. PMID:37666112<ref>PMID:37666112</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 8ime" style="background-color:#fffaf0;"></div>
== References ==
<references/>
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</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Xu YC]]
[[Category: Zhao WF]]