View source for 9zj5


==Crystal structure of SARS-CoV-2 3CL protease in complex with inhibitor IKR-I-52==
<StructureSection load='9zj5' size='340' side='right'caption='[[9zj5]], [[Resolution|resolution]] 1.76&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[9zj5]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Severe_acute_respiratory_syndrome_coronavirus_2 Severe acute respiratory syndrome coronavirus 2]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=9ZJ5 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=9ZJ5 FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 1.76&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=A1C2W:N~2~-[(2S,4R)-3-benzyl-4-methyl-2-oxo-1,3,2lambda~5~-oxazaphospholidin-2-yl]-N-{(2S)-1-hydroxy-3-[(3S)-2-oxopyrrolidin-3-yl]propan-2-yl}-L-leucinamide'>A1C2W</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=9zj5 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=9zj5 OCA], [https://pdbe.org/9zj5 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=9zj5 RCSB], [https://www.ebi.ac.uk/pdbsum/9zj5 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=9zj5 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/R1AB_SARS2 R1AB_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] (PubMed:32198291). Also able to bind an ADP-ribose-1''-phosphate (ADRP).[UniProtKB:P0C6X7]<ref>PMID:32198291</ref>   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]  Responsible for replication and transcription of the viral RNA genome.[UniProtKB:P0C6X7]  Multi-functional protein with a zinc-binding domain in N-terminus displaying RNA and DNA duplex-unwinding activities with 5' to 3' polarity. Activity of helicase is dependent on magnesium.[UniProtKB:P0C6X7]  Enzyme possessing two different activities: an exoribonuclease activity acting on both ssRNA and dsRNA in a 3' to 5' direction and a N7-guanine methyltransferase activity. Acts as a proofreading exoribonuclease for RNA replication, thereby lowering The sensitivity of the virus to RNA mutagens.[UniProtKB:P0C6X7]  Mn(2+)-dependent, uridylate-specific enzyme, which leaves 2'-3'-cyclic phosphates 5' to the cleaved bond.[UniProtKB:P0C6X7]  Methyltransferase that mediates mRNA cap 2'-O-ribose methylation to the 5'-cap structure of viral mRNAs. N7-methyl guanosine cap is a prerequisite for binding of nsp16. Therefore plays an essential role in viral mRNAs cap methylation which is essential to evade immune system.[UniProtKB:P0C6X7]
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== Publication Abstract from PubMed ==
Constant changes in SARS-CoV-2 in human populations as well as potential future spillovers from animal coronaviruses have provided the impetus for the development of additional direct-acting antivirals. We describe herein the discovery of a new class of broad-spectrum inhibitors of coronavirus 3C-like protease (3CLpro), a cysteine protease essential for viral replication and a validated drug target, that incorporate in their structure a 1,3,2-oxazaphospholidin-3-one scaffold. Inhibitors 1 and 2 potently inhibited SARS-CoV-2 3CLpro (IC(50) = 0.34 and 0.23 muM) and MERS-CoV 3CLpro (IC(50) = 0.12 and 0.09 muM), and displayed antiviral activity against SARS-CoV-2 (EC(50) = 60 and 50 nM) with low cytotoxicity (CC(50) &gt; 100 muM). Importantly, several of the synthesized compounds inhibited recombinant human cathepsin L with IC(50) values in the low nM to sub-nM range. Thus, the compounds can potentially exhibit high antiviral potency by abrogating viral entry via the inhibition of cathepsin L and viral replication by inhibition of 3CLpro. High resolution cocrystal structures were determined to elucidate the mechanism of action, identify the molecular determinants associated with binding, and to inform the optimization process.

Structure-guided design of broad-spectrum inhibitors of coronaviral proteases embodying a 1,3,2-oxazaphospholidin-3-one scaffold as a versatile design element.,Nguyen HN, Ranasinghe PS, Ilesinghe IKRS, Dampalla CS, Rathnayake AD, Liska Z, Jesri AM, Azmi Z, Nevonen DE, Kim Y, Ung AR, Taylor KE, Cooper A, Liu L, Battaile KP, Thurman HA, Gusachenko E, Lovell S, Groutas WC, Chang KO Eur J Med Chem. 2026 May 26;316:119002. doi: 10.1016/j.ejmech.2026.119002. PMID:42208369<ref>PMID:42208369</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 9zj5" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Severe acute respiratory syndrome coronavirus 2]]
[[Category: Battaile KP]]
[[Category: Groutas WC]]
[[Category: Ilesinghe IKRS]]
[[Category: Lovell S]]
[[Category: Ung AR]]