6lo0
Structural highlights
FunctionR1A_SARS Multifunctional protein involved in the transcription and replication of viral RNAs. Contains the proteinases responsible for the cleavages of the polyprotein. 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 (PubMed:23035226). May disrupt nuclear pore function by binding and displacing host NUP93 (PubMed:30943371).[1] [2] 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.[3] 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 (PubMed:17692280). Plays a role in host membrane rearrangement that leads to creation of cytoplasmic double-membrane vesicles (DMV) necessary for viral replication. Nsp3, nsp4 and nsp6 together are sufficient to form DMV (PubMed:24410069). Antagonizes innate immune induction of type I interferon by blocking the phosphorylation, dimerization and subsequent nuclear translocation of host IRF3 (PubMed:19369340, PubMed:24622840). Prevents also host NF-kappa-B signaling.[4] [5] [6] [7] [8] Plays a role in host membrane rearrangement that leads to creation of cytoplasmic double-membrane vesicles (DMV) necessary for viral replication. Alone appears incapable to induce membrane curvature, but together with nsp3 is able to induce paired membranes. Nsp3, nsp4 and nsp6 together are sufficient to form DMV.[9] [10] 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). May cleave host ATP6V1G1 thereby modifying host vacuoles intracellular pH.[PROSITE-ProRule:PRU00772][11] Plays a role in host membrane rearrangement that leads to creation of cytoplasmic double-membrane vesicles (DMV) necessary for viral replication. Nsp3, nsp4 and nsp6 together are sufficient to form DMV (PubMed:24410069). 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 (PubMed:24991833).[12] [13] 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.[14] 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.[15] May participate in viral replication by acting as a ssRNA-binding protein.[16] 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.[17] Publication Abstract from PubMedCoronavirus 3C-like protease (3CL(Pro)) is a highly conserved cysteine protease employing a catalytic dyad for its functions. 3CL(Pro) is essential to the viral life cycle and, therefore, is an attractive target for developing antiviral agents. However, the detailed catalytic mechanism of coronavirus 3CL(Pro) remains largely unknown. We took an integrated approach of employing X-ray crystallography, mutational studies, enzyme kinetics study, and inhibitors to gain insights into the mechanism. Such experimental work is supplemented by computational studies, including the prereaction state analysis, the ab initio calculation of the critical catalytic step, and the molecular dynamic simulation of the wild-type and mutant enzymes. Taken together, such studies allowed us to identify a residue pair (Glu-His) and a conserved His as critical for binding; a conserved GSCGS motif as important for the start of catalysis, a partial negative charge cluster (PNCC) formed by Arg-Tyr-Asp as essential for catalysis, and a conserved water molecule mediating the remote interaction between PNCC and catalytic dyad. The data collected and our insights into the detailed mechanism have allowed us to achieve a good understanding of the difference in catalytic efficiency between 3CL(Pro) from SARS and MERS, conduct mutational studies to improve the catalytic activity by 8-fold, optimize existing inhibitors to improve the potency by 4-fold, and identify a potential allosteric site for inhibitor design. All such results reinforce each other to support the overall catalytic mechanism proposed herein. Comprehensive Insights into the Catalytic Mechanism of Middle East Respiratory Syndrome 3C-Like Protease and Severe Acute Respiratory Syndrome 3C-Like Protease.,Wang H, He S, Deng W, Zhang Y, Li G, Sun J, Zhao W, Guo Y, Yin Z, Li D, Shang L ACS Catal. 2020;10:5871-5890. doi: 10.1021/acscatal.0c00110. Epub 2020 Apr 28. PMID:32391184[18] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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