6-Thioguanine blocks SARS-CoV-2 replication by inhibition of PLpro protease activities

Swaim, Caleb D.; Perng, Yi-Chieh; Zhao, Xu; Canadeo, Larissa A.; Harastani, Houda H.; Boon, Adrianus C. M.; Lenschow, Deborah J.; Huibregtse, Jon M.

doi:10.1101/2020.07.01.183020

Cited by 30 publications

(27 citation statements)

References 16 publications

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“…S4 ), but all other drugs were ineffective. These results contradict with several published studies which demonstrated that disulfiram 44 , 6-TG 45 , 46 and ebselen 43 inhibited the protease activity of MERS-CoV and SARS-CoV PLpro in vitro , and 6-TG inhibited SARS-CoV-2 replication at submicromolar levels 47 . The discrepancy may stem from different substrates used for assessing inhibitor efficacy.…”

Section: Resultscontrasting

confidence: 99%

Crystal structure of SARS-CoV-2 papain-like protease

Gao

Qin

Chen

et al. 2021

Acta Pharmaceutica Sinica B

268

291

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The pandemic of coronavirus disease 2019 (COVID-19) is changing the world like never before. This crisis is unlikely contained in the absence of effective therapeutics or vaccine. The papain-like protease (PLpro) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) plays essential roles in virus replication and immune evasion, presenting a charming drug target. Given the PLpro proteases of SARS-CoV-2 and SARS-CoV share significant homology, inhibitor developed for SARS-CoV PLpro is a promising starting point of therapeutic development. In this study, we sought to provide structural frameworks for PLpro inhibitor design. We determined the unliganded structure of SARS-CoV-2 PLpro mutant C111S, which shares many structural features of SARS-CoV PLpro. This crystal form has unique packing, high solvent content and reasonable resolution 2.5 Å, hence provides a good possibility for fragment-based screening using crystallographic approach. We characterized the protease activity of PLpro in cleaving synthetic peptide harboring nsp2/nsp3 juncture. We demonstrate that a potent SARS-CoV PLpro inhibitor GRL0617 is highly effective in inhibiting protease activity of SARS-CoV-2 with the IC 50 of 2.2 ± 0.3 μmol/L. We then determined the structure of SARS-CoV-2 PLpro complexed by GRL0617 to 2.6 Å, showing the inhibitor accommodates the S3–S4 pockets of the substrate binding cleft. The binding of GRL0617 induces closure of the BL2 loop and narrows the substrate binding cleft, whereas the binding of a tetrapeptide substrate enlarges the cleft. Hence, our results suggest a mechanism of GRL0617 inhibition, that GRL0617 not only occupies the substrate pockets, but also seals the entrance to the substrate binding cleft hence prevents the binding of the LXGG motif of the substrate.

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Section: Resultscontrasting

confidence: 99%

Crystal structure of SARS-CoV-2 papain-like protease

Gao

Qin

Chen

et al. 2021

Acta Pharmaceutica Sinica B

268

291

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“… 17 – 19 Indeed, some recent studies have focused primarily on targeting this activity to modulate the immune evasion of SARS-CoV-2. 20 – 22 In addition, because PLpro resides in a multidomain, membrane-bound protein, it is possible that compounds that inhibit the soluble protease may not have as great of an effect on the full nsp3 protein and therefore on viral replication. 23 In the studies in Refs.…”

Section: Discussionmentioning

confidence: 99%

High-Throughput Screening for Drugs That Inhibit Papain-Like Protease in SARS-CoV-2

et al. 2020

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The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in late 2019 has triggered an ongoing global pandemic whereby infection may result in a lethal severe pneumonia-like disease designated as coronavirus disease 2019 (COVID-19). To date, millions of confirmed cases and hundreds of thousands of deaths have been reported worldwide, and there are currently no medical countermeasures available to prevent or treat the disease. The purported development of a vaccine could require at least 1–4 years, while the typical timeline from hit finding to drug registration of an antiviral is >10 years. Thus, repositioning of known drugs can significantly accelerate the development and deployment of therapies for COVID-19. To identify therapeutics that can be repurposed as SARS-CoV-2 antivirals, we developed and initiated a high-throughput cell-based screen that incorporates the essential viral papain-like protease (PLpro) and its peptide cleavage site into a luciferase complementation assay to evaluate the efficacy of known drugs encompassing approximately 15,000 clinical-stage or US Food and Drug Administration (FDA)-approved small molecules. Confirmed inhibitors were also tested to determine their cytotoxic properties. Here, we report the identification of four clinically relevant drugs that exhibit selective inhibition of the SARS-CoV-2 viral PLpro.

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“…Klemm et al showed that benzodioxolane analogs 3j , 3k , and 5c , which inhibit SARS-CoV PL pro in the sub-micromolar range ( Báez-Santos et al, 2014 ) displayed similar inhibitory activity against SARS-CoV-2 PL pro ( Klemm et al, 2020 ). Two other compounds have been shown to inhibit SARS-CoV-2 PL pro in vitro , inhibiting viral production in cell culture: the approved chemotherapy agent 6-Thioguanine ( Swaim et al, 2020 ), and the anti-dengue protease inhibitor mycophenolic acid ( Kato et al, 2020 ).…”

Section: Druggability Characterization Of Sars-cov-2 Proteinsmentioning

confidence: 99%

Functional and druggability analysis of the SARS-CoV-2 proteome

Cavasotto

Lamas

Maggini

2021

European Journal of Pharmacology

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The infectious coronavirus disease (COVID-19) pandemic, caused by the coronavirus SARS-CoV-2, appeared in December 2019 in Wuhan, China, and has spread worldwide. As of today, more than 46 million people have been infected and over 1.2 million fatalities. With the purpose of contributing to the development of effective therapeutics, we performed an in silico determination of binding hot-spots and an assessment of their druggability within the complete SARS-CoV-2 proteome. All structural, non-structural, and accessory proteins have been studied, and whenever experimental structural data of SARS-CoV-2 proteins were not available, homology models were built based on solved SARS-CoV structures. Several potential allosteric or protein-protein interaction druggable sites on different viral targets were identified, knowledge that could be used to expand current drug discovery endeavors beyond the currently explored cysteine proteases and the polymerase complex. It is our hope that this study will support the efforts of the scientific community both in understanding the molecular determinants of this disease and in widening the repertoire of viral targets in the quest for repurposed or novel drugs against COVID-19.

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6-Thioguanine blocks SARS-CoV-2 replication by inhibition of PLpro protease activities

Cited by 30 publications

References 16 publications

Crystal structure of SARS-CoV-2 papain-like protease

Crystal structure of SARS-CoV-2 papain-like protease

High-Throughput Screening for Drugs That Inhibit Papain-Like Protease in SARS-CoV-2

Functional and druggability analysis of the SARS-CoV-2 proteome

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