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==Structure of Ternary Complex of mouse cGAS with dsDNA and Bound ATP: with 10mM Mg2+ and 0.2mM Mn2+==
<StructureSection load='8gir' size='340' side='right'caption='[[8gir]], [[Resolution|resolution]] 2.50&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[8gir]] is a 6 chain structure with sequence from [https://en.wikipedia.org/wiki/Mus_musculus Mus musculus] and [https://en.wikipedia.org/wiki/Synthetic_construct Synthetic construct]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=8GIR OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=8GIR 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]] 2.5&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=ATP:ADENOSINE-5-TRIPHOSPHATE'>ATP</scene>, <scene name='pdbligand=MN:MANGANESE+(II)+ION'>MN</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=8gir FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=8gir OCA], [https://pdbe.org/8gir PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=8gir RCSB], [https://www.ebi.ac.uk/pdbsum/8gir PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=8gir 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.
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== Publication Abstract from PubMed ==
cGAS activates innate immune responses against cytosolic double-stranded DNA. Here, by determining crystal structures of cGAS at various reaction stages, we report a unifying catalytic mechanism. apo-cGAS assumes an array of inactive conformations and binds NTPs nonproductively. Dimerization-coupled double-stranded DNA-binding then affixes the active site into a rigid lock for productive metal*substrate binding. A web-like network of protein*NTP, intra-NTP, and inter-NTP interactions ensures the stepwise synthesis of 2'-5'/3'-5'-linked cGAMP while discriminating against noncognate NTPs and off-pathway intermediates. One divalent metal is sufficient for productive substrate binding, and capturing the second divalent metal is tightly coupled to nucleotide and linkage specificities, a process which manganese is preferred over magnesium by 100-fold. Additionally, we elucidate how mouse cGAS achieves more stringent NTP and linkage specificities than human cGAS. Together, our results reveal that an adaptable, yet precise lock-and-key-like mechanism underpins cGAS catalysis.

The structural basis for 2'-5'/3'-5'-cGAMP synthesis by cGAS.,Wu S, Gabelli SB, Sohn J Nat Commun. 2024 May 13;15(1):4012. doi: 10.1038/s41467-024-48365-3. PMID:38740774<ref>PMID:38740774</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
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== References ==
<references/>
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</StructureSection>
[[Category: Large Structures]]
[[Category: Mus musculus]]
[[Category: Synthetic construct]]
[[Category: Sohn J]]
[[Category: Wu S]]