6lrc
Human cGAS catalytic domain bound with the inhibitor PF-06928215
Structural highlights
FunctionCGAS_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) has been recently uncovered to be a promising therapeutic target for immune-associated diseases. Until now, only a few inhibitors have been identified through high-throughput screening campaigns. Here, we reported the discovery of novel inhibitors for the catalytic domain of human cGAS (h-cGAS(CD)) by virtual screening for the first time. To generate a reliable docking mode, we first obtained a high-resolution crystal structure of h-cGAS(CD) in complex with PF-06928215, a known inhibitor of h-cGAS, followed by molecular dynamics simulations on this complex structure. Four fragment hits were identified by the virtual screening together with a thermal shift assay. The crystal structures of these four compounds in complex with h-cGAS(CD) were subsequently determined, and the binding modes of the compounds were similar to those predicted by molecular docking, supporting the reliability of the docking model. In addition, an enzyme activity assay identified compound 18 (IC50 = 29.88 +/- 3.20 muM) from the compounds predicted by the virtual screening. A similarity search of compound 18 followed by a second virtual screening led to the discovery of compounds S2 (IC50 = 13.1 +/- 0.09 muM) and S3 (IC50 = 4.9 +/- 0.26 muM) as h-cGAS inhibitors with improved potency. Therefore, the present study not only provides the validated hit compounds for further development of h-cGAS inhibitors but also demonstrates a cross-validation study of virtual screening, in vitro experimental assays, and crystal structure determination. In Silico Screening-Based Discovery of Novel Inhibitors of Human Cyclic GMP-AMP Synthase: A Cross-Validation Study of Molecular Docking and Experimental Testing.,Zhao W, Xiong M, Yuan X, Li M, Sun H, Xu Y J Chem Inf Model. 2020 Jun 22;60(6):3265-3276. doi: 10.1021/acs.jcim.0c00171., Epub 2020 Jun 9. PMID:32459092[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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