Structural highlights
Function
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.[1] [2]
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[3]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Schoggins JW, Wilson SJ, Panis M, Murphy MY, Jones CT, Bieniasz P, Rice CM. A diverse range of gene products are effectors of the type I interferon antiviral response. Nature. 2011 Apr 28;472(7344):481-5. doi: 10.1038/nature09907. Epub 2011 Apr 10. PMID:21478870 doi:10.1038/nature09907
- ↑ Sun L, Wu J, Du F, Chen X, Chen ZJ. Cyclic GMP-AMP synthase is a cytosolic DNA sensor that activates the type I interferon pathway. Science. 2013 Feb 15;339(6121):786-91. doi: 10.1126/science.1232458. Epub 2012, Dec 20. PMID:23258413 doi:10.1126/science.1232458
- ↑ Wu S, Gabelli SB, Sohn J. The structural basis for 2'-5'/3'-5'-cGAMP synthesis by cGAS. Nat Commun. 2024 May 13;15(1):4012. PMID:38740774 doi:10.1038/s41467-024-48365-3
