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  • In Silico Screening-Based Discovery of Novel Inhibitors of Human Cyclic GMP-AMP Synthase: A Cross-Validation Study of Molecular Docking and Experimental Testing.

In Silico Screening-Based Discovery of Novel Inhibitors of Human Cyclic GMP-AMP Synthase: A Cross-Validation Study of Molecular Docking and Experimental Testing.

Journal of chemical information and modeling (2020-05-28)
Wenfeng Zhao, Muya Xiong, Xiaojing Yuan, Minjun Li, Hongbin Sun, Yechun Xu
ABSTRACT

Cyclic 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-cGASCD) by virtual screening for the first time. To generate a reliable docking mode, we first obtained a high-resolution crystal structure of h-cGASCD 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-cGASCD 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 μM) 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 μM) and S3 (IC50 = 4.9 ± 0.26 μM) 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.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
PF-06928215, cis-racemate, ≥98% (HPLC)
Sigma-Aldrich
Pyrophosphatase, Inorganic from Escherichia coli, recombinant, expressed in E. coli, lyophilized powder, ≥90%, ≥800 units/mg protein