View source for 4k9b


==Structure of Ternary Complex of cGAS with dsDNA and Bound c[G(2 ,5 )pA(3 ,5 )p]==
<StructureSection load='4k9b' size='340' side='right'caption='[[4k9b]], [[Resolution|resolution]] 2.26&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[4k9b]] is a 3 chain structure with sequence from [https://en.wikipedia.org/wiki/Mus_musculus Mus musculus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4K9B OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4K9B 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]] 2.26&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=5GP:GUANOSINE-5-MONOPHOSPHATE'>5GP</scene>, <scene name='pdbligand=AMP:ADENOSINE+MONOPHOSPHATE'>AMP</scene>, <scene name='pdbligand=PO4:PHOSPHATE+ION'>PO4</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=4k9b FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4k9b OCA], [https://pdbe.org/4k9b PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4k9b RCSB], [https://www.ebi.ac.uk/pdbsum/4k9b PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4k9b ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/CGAS_MOUSE CGAS_MOUSE] 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.
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Recent studies identified cyclic GMP-AMP (cGAMP) as a metazoan second messenger triggering an interferon response. cGAMP is generated from GTP and ATP by cytoplasmic dsDNA sensor cGAMP synthase (cGAS). We combined structural, chemical, biochemical, and cellular assays to demonstrate that this second messenger contains G(2',5')pA and A(3',5')pG phosphodiester linkages, designated c[G(2',5')pA(3',5')p]. We show that, upon dsDNA binding, cGAS is activated through conformational transitions, resulting in formation of a catalytically competent and accessible nucleotide-binding pocket for generation of c[G(2',5')pA(3',5')p]. We demonstrate that cyclization occurs in a stepwise manner through initial generation of 5'-pppG(2',5')pA prior to cyclization to c[G(2',5')pA(3',5')p], with the latter positioned precisely in the catalytic pocket. Mutants of cGAS dsDNA-binding or catalytic pocket residues exhibit reduced or abrogated activity. Our studies have identified c[G(2',5')pA(3',5')p] as a founding member of a family of metazoan 2',5'-containing cyclic heterodinucleotide second messengers distinct from bacterial 3',5' cyclic dinucleotides.

Cyclic [G(2',5')pA(3',5')p] is the metazoan second messenger produced by DNA-activated cyclic GMP-AMP synthase.,Gao P, Ascano M, Wu Y, Barchet W, Gaffney BL, Zillinger T, Serganov AA, Liu Y, Jones RA, Hartmann G, Tuschl T, Patel DJ Cell. 2013 May 23;153(5):1094-107. doi: 10.1016/j.cell.2013.04.046. Epub 2013 May, 3. PMID:23647843<ref>PMID:23647843</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 4k9b" style="background-color:#fffaf0;"></div>

==See Also==
*[[Cyclic GMP-AMP synthase 3D synthase|Cyclic GMP-AMP synthase 3D synthase]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Mus musculus]]
[[Category: Gao P]]
[[Category: Patel DJ]]
[[Category: Wu Y]]