5v8n | pdb_00005v8n
Discovery of a high affinity inhibitor of cGAS
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 PubMedCyclic GMP-AMP synthase (cGAS) initiates the innate immune system in response to cytosolic dsDNA. After binding and activation from dsDNA, cGAS uses ATP and GTP to synthesize 2', 3' -cGAMP (cGAMP), a cyclic dinucleotide second messenger with mixed 2'-5' and 3'-5' phosphodiester bonds. Inappropriate stimulation of cGAS has been implicated in autoimmune disease such as systemic lupus erythematosus, thus inhibition of cGAS may be of therapeutic benefit in some diseases; however, the size and polarity of the cGAS active site makes it a challenging target for the development of conventional substrate-competitive inhibitors. We report here the development of a high affinity (KD = 200 nM) inhibitor from a low affinity fragment hit with supporting biochemical and structural data showing these molecules bind to the cGAS active site. We also report a new high throughput cGAS fluorescence polarization (FP)-based assay to enable the rapid identification and optimization of cGAS inhibitors. This FP assay uses Cy5-labelled cGAMP in combination with a novel high affinity monoclonal antibody that specifically recognizes cGAMP with no cross reactivity to cAMP, cGMP, ATP, or GTP. Given its role in the innate immune response, cGAS is a promising therapeutic target for autoinflammatory disease. Our results demonstrate its druggability, provide a high affinity tool compound, and establish a high throughput assay for the identification of next generation cGAS inhibitors. Discovery of PF-06928215 as a high affinity inhibitor of cGAS enabled by a novel fluorescence polarization assay.,Hall J, Brault A, Vincent F, Weng S, Wang H, Dumlao D, Aulabaugh A, Aivazian D, Castro D, Chen M, Culp J, Dower K, Gardner J, Hawrylik S, Golenbock D, Hepworth D, Horn M, Jones L, Jones P, Latz E, Li J, Lin LL, Lin W, Lin D, Lovering F, Niljanskul N, Nistler R, Pierce B, Plotnikova O, Schmitt D, Shanker S, Smith J, Snyder W, Subashi T, Trujillo J, Tyminski E, Wang G, Wong J, Lefker B, Dakin L, Leach K PLoS One. 2017 Sep 21;12(9):e0184843. doi: 10.1371/journal.pone.0184843., eCollection 2017. PMID:28934246[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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