9t0r
Crystal structure of SARS-CoV-2 Mpro in complex with GK729
Structural highlights
FunctionR1A_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 PubMedThe SARS-CoV-2 main protease (M(pro)), an enzyme essential for viral replication and lacking a human homologue, has emerged as a highly attractive target for the development of novel antiviral agents. Although several M(pro) inhibitors have been developed - some receiving regulatory approval - their use is sometimes limited by drug-drug interactions. In this study, we designed and synthesized peptidomimetic SARS-CoV-2 M(pro) inhibitors incorporating a novel thiazolyl 4-carboxylate ketone warhead, previously employed by our group in the development of cytosolic phospholipase A(2) inhibitors. The synthesized compounds were evaluated for their in vitro inhibitory potency against SARS-CoV-2 M(pro), and a highly potent M(pro) inhibitor (GK730) was identified (IC(50) 5.75 nM). The melting temperature of the M(pro)-GK730 complex revealed high stability, consistent with the high inhibitory potency. The X-ray crystal structures of inhibitors GK729 and GK730 bound to M(pro) were determined, providing insights into the binding interactions and mechanism of action. Studies on the host cell proteases cathepsin B and L showed that GK730 did not inhibit cathepsin B, while exhibited weak inhibition of cathepsin L. Furthermore, GK730 demonstrated an EC(50) value of 5.70 muM against a wild-type SARS-CoV-2 strain in Vero E6 cells and minimal cytotoxicity (CC(50) value greater than 100 muM). Thiazolyl 4-carboxylate ketone as a new warhead for a highly potent SARS-CoV-2 main protease inhibitor.,Theodoropoulou MA, El Kilani H, Mantzourani C, Jochmans D, Neyts J, Zhang K, Roske J, Kokotou MG, Hilgenfeld R, Kokotos G Eur J Med Chem. 2026 Feb 5;303:118436. doi: 10.1016/j.ejmech.2025.118436. Epub , 2025 Nov 29. PMID:41344111[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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