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2.
J Med Chem ; 65(8): 6231-6249, 2022 04 28.
Article in English | MEDLINE | ID: covidwho-1867997

ABSTRACT

Enzymes involved in RNA capping of SARS-CoV-2 are essential for the stability of viral RNA, translation of mRNAs, and virus evasion from innate immunity, making them attractive targets for antiviral agents. In this work, we focused on the design and synthesis of nucleoside-derived inhibitors against the SARS-CoV-2 nsp14 (N7-guanine)-methyltransferase (N7-MTase) that catalyzes the transfer of the methyl group from the S-adenosyl-l-methionine (SAM) cofactor to the N7-guanosine cap. Seven compounds out of 39 SAM analogues showed remarkable double-digit nanomolar inhibitory activity against the N7-MTase nsp14. Molecular docking supported the structure-activity relationships of these inhibitors and a bisubstrate-based mechanism of action. The three most potent inhibitors significantly stabilized nsp14 (ΔTm ≈ 11 °C), and the best inhibitor demonstrated high selectivity for nsp14 over human RNA N7-MTase.


Subject(s)
COVID-19 , SARS-CoV-2 , COVID-19/drug therapy , COVID-19/virology , Exoribonucleases/antagonists & inhibitors , Exoribonucleases/chemistry , Humans , Methyltransferases , Molecular Docking Simulation , RNA, Viral/genetics , S-Adenosylmethionine , SARS-CoV-2/drug effects , SARS-CoV-2/enzymology , Sulfonamides/pharmacology , Viral Nonstructural Proteins/antagonists & inhibitors , Viral Nonstructural Proteins/chemistry
3.
J Virol ; 96(8): e0012822, 2022 04 27.
Article in English | MEDLINE | ID: covidwho-1765079

ABSTRACT

The spike protein (S) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) directs infection of the lungs and other tissues following its binding to the angiotensin-converting enzyme 2 (ACE2) receptor. For effective infection, the S protein is cleaved at two sites: S1/S2 and S2'. The "priming" of the surface S protein at S1/S2 (PRRAR685↓) [the underlined basic amino acids refer to critical residues needed for the furin recognition] by furin has been shown to be important for SARS-CoV-2 infectivity in cells and small-animal models. In this study, for the first time we unambiguously identified by proteomics the fusion activation site S2' as KPSKR815↓ (the underlined basic amino acids refer to critical residues needed for the furin recognition) and demonstrated that this cleavage was strongly enhanced by ACE2 engagement with the S protein. Novel pharmacological furin inhibitors (BOS inhibitors) effectively blocked endogenous S protein processing at both sites in HeLa cells, and SARS-CoV-2 infection of lung-derived Calu-3 cells was completely prevented by combined inhibitors of furin (BOS) and type II transmembrane serine protease 2 (TMPRSS2) (camostat). Quantitative analyses of cell-to-cell fusion and S protein processing revealed that ACE2 shedding by TMPRSS2 was required for TMPRSS2-mediated enhancement of fusion in the absence of S1/S2 priming. We further demonstrated that the collectrin dimerization domain of ACE2 was essential for the effect of TMPRSS2 on cell-to-cell fusion. Overall, our results indicate that furin and TMPRSS2 act synergistically in viral entry and infectivity, supporting the combination of furin and TMPRSS2 inhibitors as potent antivirals against SARS-CoV-2. IMPORTANCE SARS-CoV-2, the etiological agent of COVID-19, has so far resulted in >6.1 million deaths worldwide. The spike protein (S) of the virus directs infection of the lungs and other tissues by binding the angiotensin-converting enzyme 2 (ACE2) receptor. For effective infection, the S protein is cleaved at two sites: S1/S2 and S2'. Cleavage at S1/S2 induces a conformational change favoring the S protein recognition by ACE2. The S2' cleavage is critical for triggering membrane fusion and virus entry into host cells. Our study highlights the complex dynamics of interaction between the S protein, ACE2, and the host proteases furin and TMPRSS2 during SARS-CoV-2 entry and suggests that the combination of a nontoxic furin inhibitor with a TMPRSS2 inhibitor significantly reduces viral entry in lung cells, as evidenced by an average synergistic ∼95% reduction of viral infection. This represents a powerful novel antiviral approach to reduce viral spread in individuals infected by SARS-CoV-2 or future related coronaviruses.


Subject(s)
COVID-19 , Furin , SARS-CoV-2 , Serine Endopeptidases , Angiotensin-Converting Enzyme 2/metabolism , Animals , COVID-19/pathology , COVID-19/virology , Furin/metabolism , HeLa Cells , Humans , SARS-CoV-2/genetics , SARS-CoV-2/pathogenicity , Serine Endopeptidases/metabolism , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/metabolism , Virus Internalization
4.
Eur J Med Chem ; 201: 112557, 2020 Sep 01.
Article in English | MEDLINE | ID: covidwho-597389

ABSTRACT

The spreading of new viruses is known to provoke global human health threat. The current COVID-19 pandemic caused by the recently emerged coronavirus SARS-CoV-2 is one significant and unfortunate example of what the world will have to face in the future with emerging viruses in absence of appropriate treatment. The discovery of potent and specific antiviral inhibitors and/or vaccines to fight these massive outbreaks is an urgent research priority. Enzymes involved in the capping pathway of viruses and more specifically RNA N7- or 2'O-methyltransferases (MTases) are now admitted as potential targets for antiviral chemotherapy. We designed bisubstrate inhibitors by mimicking the transition state of the 2'-O-methylation of the cap RNA in order to block viral 2'-O MTases. This work resulted in the synthesis of 16 adenine dinucleosides with both adenosines connected by various nitrogen-containing linkers. Unexpectedly, all the bisubstrate compounds were barely active against 2'-O MTases of several flaviviruses or SARS-CoV but surprisingly, seven of them showed efficient and specific inhibition against SARS-CoV N7-MTase (nsp14) in the micromolar to submicromolar range. The most active nsp14 inhibitor identified is as potent as but particularly more specific than the broad-spectrum MTase inhibitor, sinefungin. Molecular docking suggests that the inhibitor binds to a pocket formed by the S-adenosyl methionine (SAM) and cap RNA binding sites, conserved among SARS-CoV nsp14. These dinucleoside SAM analogs will serve as starting points for the development of next inhibitors for SARS-CoV-2 nsp14 N7-MTase.


Subject(s)
Coronavirus Infections/drug therapy , Exoribonucleases/antagonists & inhibitors , Methyltransferases/antagonists & inhibitors , Nucleosides/chemistry , Pneumonia, Viral/drug therapy , RNA Caps/metabolism , S-Adenosylmethionine/analogs & derivatives , S-Adenosylmethionine/pharmacology , Viral Nonstructural Proteins/antagonists & inhibitors , Adenine/chemistry , Betacoronavirus/isolation & purification , COVID-19 , Coronavirus Infections/metabolism , Coronavirus Infections/virology , Exoribonucleases/metabolism , Humans , Methylation , Methyltransferases/metabolism , Molecular Docking Simulation , Pandemics , Pneumonia, Viral/metabolism , Pneumonia, Viral/virology , RNA Caps/chemistry , RNA Caps/genetics , RNA, Viral/genetics , RNA, Viral/metabolism , SARS-CoV-2 , Viral Nonstructural Proteins/metabolism
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