Structural highlights
Function
R1A_SARS2 Multifunctional protein involved in the transcription and replication of viral RNAs. Contains the proteinases responsible for the cleavages of the polyprotein.[UniProtKB:P0C6X7] Inhibits host translation by interacting with the 40S ribosomal subunit. The nsp1-40S ribosome complex further induces an endonucleolytic cleavage near the 5'UTR of host mRNAs, targeting them for degradation. Viral mRNAs are not susceptible to nsp1-mediated endonucleolytic RNA cleavage thanks to the presence of a 5'-end leader sequence and are therefore protected from degradation. By suppressing host gene expression, nsp1 facilitates efficient viral gene expression in infected cells and evasion from host immune response.[UniProtKB:P0C6X7] May play a role in the modulation of host cell survival signaling pathway by interacting with host PHB and PHB2. Indeed, these two proteins play a role in maintaining the functional integrity of the mitochondria and protecting cells from various stresses.[UniProtKB:P0C6X7] Responsible for the cleavages located at the N-terminus of the replicase polyprotein. In addition, PL-PRO possesses a deubiquitinating/deISGylating activity and processes both 'Lys-48'- and 'Lys-63'-linked polyubiquitin chains from cellular substrates. Participates together with nsp4 in the assembly of virally-induced cytoplasmic double-membrane vesicles necessary for viral replication. Antagonizes innate immune induction of type I interferon by blocking the phosphorylation, dimerization and subsequent nuclear translocation of host IRF3. Prevents also host NF-kappa-B signaling.[UniProtKB:P0C6X7] Participates in the assembly of virally-induced cytoplasmic double-membrane vesicles necessary for viral replication.[UniProtKB:P0C6X7] Cleaves the C-terminus of replicase polyprotein at 11 sites. Recognizes substrates containing the core sequence [ILMVF]-Q-|-[SGACN]. Also able to bind an ADP-ribose-1-phosphate (ADRP).[UniProtKB:P0C6X7] Plays a role in the initial induction of autophagosomes from host reticulum endoplasmic. Later, limits the expansion of these phagosomes that are no longer able to deliver viral components to lysosomes.[UniProtKB:P0C6X7] Forms a hexadecamer with nsp8 (8 subunits of each) that may participate in viral replication by acting as a primase. Alternatively, may synthesize substantially longer products than oligonucleotide primers.[UniProtKB:P0C6X7] Forms a hexadecamer with nsp7 (8 subunits of each) that may participate in viral replication by acting as a primase. Alternatively, may synthesize substantially longer products than oligonucleotide primers.[UniProtKB:P0C6X7] May participate in viral replication by acting as a ssRNA-binding protein.[UniProtKB:P0C6X7] Plays a pivotal role in viral transcription by stimulating both nsp14 3'-5' exoribonuclease and nsp16 2'-O-methyltransferase activities. Therefore plays an essential role in viral mRNAs cap methylation.[UniProtKB:P0C6X7]
Publication Abstract from PubMed
SARS-CoV-2 main protease (M(pro)/3CL(pro)) is a crucial target for therapeutics, which is responsible for viral polyprotein cleavage and plays a vital role in virus replication and survival. Recent studies suggest that 2-phenylbenzisoselenazol-3(2H)-one (ebselen) is a potent covalent inhibitor of M(pro), which affects its enzymatic activity and virus survival. Herein, we synthesized various ebselen derivatives to understand the mechanism of M(pro) inhibition by ebselen. Using ebselen derivatives, we characterized the detailed interaction mechanism with M(pro). We discovered that modification of the parent ebselen inhibitor with an electron-withdrawing group (NO(2)) increases the inhibition efficacy by 2-fold. We also solved the structure of an M(pro) complex with an ebselen derivative showing the mechanism of inhibition by blocking the catalytic Cys145 of M(pro). Using a combination of crystal structures and LC-MS data, we showed that M(pro) hydrolyzes the new ebselen derivative and leaves behind selenium (Se) bound with Cys145 of the catalytic dyad of M(pro). We also described the binding profile of ebselen-based inhibitors using molecular modeling predictions supported by binding and inhibition assays. Furthermore, we have also solved the crystal structure of catalytically inactive mutant H41N-M(pro), which represents the inactive state of the protein where the substrate binding pocket is blocked. The inhibited structure of H41N-M(pro) shows gatekeeper residues in the substrate binding pocket responsible for blocking the substrate binding; mutation of these gatekeeper residues leads to hyperactive M(pro).
Detailed Insights into the Inhibitory Mechanism of New Ebselen Derivatives against Main Protease (M(pro)) of Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2).,Sahoo P, Lenka DR, Batabyal M, Pain PK, Kumar S, Manna D, Kumar A ACS Pharmacol Transl Sci. 2022 Dec 23;6(1):171-180. doi: , 10.1021/acsptsci.2c00203. eCollection 2023 Jan 13. PMID:36650888[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Sahoo P, Lenka DR, Batabyal M, Pain PK, Kumar S, Manna D, Kumar A. Detailed Insights into the Inhibitory Mechanism of New Ebselen Derivatives against Main Protease (M(pro)) of Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2). ACS Pharmacol Transl Sci. 2022 Dec 23;6(1):171-180. PMID:36650888 doi:10.1021/acsptsci.2c00203
