View source for 9ssn


==Crystal structure of SARS-CoV-2 Mpro in complex with RK-240==
<StructureSection load='9ssn' size='340' side='right'caption='[[9ssn]], [[Resolution|resolution]] 1.50&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[9ssn]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Severe_acute_respiratory_syndrome_coronavirus Severe acute respiratory syndrome coronavirus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=9SSN OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=9SSN 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]] 1.5&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=A1JQX:(2~{S},5~{S},11~{E})-2-(cyclopropylmethyl)-5-(iminomethyl)-1,4,9,16-tetrazabicyclo[15.3.1]henicosa-11,17,19-triene-3,8,15,21-tetrone'>A1JQX</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=9ssn FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=9ssn OCA], [https://pdbe.org/9ssn PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=9ssn RCSB], [https://www.ebi.ac.uk/pdbsum/9ssn PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=9ssn 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 ==
Viral proteases represent validated targets for direct-acting antivirals and the treatment of associated infections. In co-crystal structures of M(pro) of SARS-CoV-2 with peptidomimetic inhibitors, we noticed a spatial proximity of sidechains filling the S1' and S2 pockets, as well as those filling S3 and S1 pockets. To enhance molecular rigidity, the proximal residues were conformationally fixed by macrocyclization. We report the synthesis of two macrocyclic series, i.e. exocyclic nitriles with linked P3 and P1 residues and endocyclic alpha-ketoamides with linked P1' and P2 residues, and characterize their binding modes and bioactivities. The 17-membered macrocyclic alpha-ketoamide 20 f inhibited M(pro) (IC(5)(0) = 370 nM) and exerted anti-SARS-CoV-2 effects (EC(5)(0) = 1.9 muM). Leveraging structural similarities between M(pro) and the 3C(pro) of enterovirus D68, we describe with two co-crystal structures how alpha-ketoamide macrocycles bound to and inhibited the enteroviral protease. Notably, 20 f exhibited very potent antiviral activities with EC(5)(0)'s of 33, 133, and 146 nM against EV-D68, EV-A71, and CVB3, respectively. The study demonstrates how broad-spectrum activity can be achieved with direct-acting antivirals.

Structure-based macrocyclization of alpha-ketoamides leads to potent inhibitors of coronaviral and enteroviral proteases.,Akula RK, El Kilani H, Metzen A, Joshi S, Durmaz H, Veenstra R, Roske J, Hurdiss DL, Van Kuppeveld FJM, Rox K, Hilgenfeld R, Bronstrup M Commun Chem. 2026 Aug 6;9(1):269. doi: 10.1038/s42004-026-02151-y. PMID:42562838<ref>PMID:42562838</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 9ssn" style="background-color:#fffaf0;"></div>
== References ==
<references/>
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</StructureSection>
[[Category: Large Structures]]
[[Category: Severe acute respiratory syndrome coronavirus]]
[[Category: El Kilani H]]
[[Category: Hilgenfeld R]]