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From Proteopedia
Structure of the SARS-CoV-2 macrodomain (NSP3) in complex with ADP-ribose
Structural highlights
Function[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][1] 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] Publication Abstract from PubMedSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and other SARS-related CoVs encode 3 tandem macrodomains within non-structural protein 3 (nsp3). The first macrodomain, Mac1, is conserved throughout CoVs, and binds to and hydrolyzes mono-ADP-ribose (MAR) from target proteins. Mac1 likely counters host-mediated anti-viral ADP-ribosylation, a posttranslational modification that is part of the host response to viral infections. Mac1 is essential for pathogenesis in multiple animal models of CoV infection, implicating it as a virulence factor and potential therapeutic target. Here we report the crystal structure of SARS-CoV-2 Mac1 in complex with ADP-ribose. SARS-CoV-2, SARS-CoV and MERS-CoV Mac1 exhibit similar structural folds and all 3 proteins bound to ADP-ribose with low muM affinities. Importantly, using ADP-ribose detecting binding reagents in both a gel-based assay and novel ELISA assays, we demonstrated de-MARylating activity for all 3 CoV Mac1 proteins, with the SARS-CoV-2 Mac1 protein leading to a more rapid loss of substrate compared to the others. In addition, none of these enzymes could hydrolyze poly-ADP-ribose. We conclude that the SARS-CoV-2 and other CoV Mac1 proteins are MAR-hydrolases with similar functions, indicating that compounds targeting CoV Mac1 proteins may have broad anti-CoV activity.IMPORTANCE SARS-CoV-2 has recently emerged into the human population and has led to a worldwide pandemic of COVID-19 that has caused greater than 1.2 million deaths worldwide. With, no currently approved treatments, novel therapeutic strategies are desperately needed. All coronaviruses encode for a highly conserved macrodomain (Mac1) that binds to and removes ADP-ribose adducts from proteins in a dynamic post-translational process increasingly recognized as an important factor that regulates viral infection. The macrodomain is essential for CoV pathogenesis and may be a novel therapeutic target. Thus, understanding its biochemistry and enzyme activity are critical first steps for these efforts. Here we report the crystal structure of SARS-CoV-2 Mac1 in complex with ADP-ribose, and describe its ADP-ribose binding and hydrolysis activities in direct comparison to SARS-CoV and MERS-CoV Mac1 proteins. These results are an important first step for the design and testing of potential therapies targeting this unique protein domain. The SARS-CoV-2 conserved macrodomain is a mono-ADP-ribosylhydrolase.,Alhammad YMO, Kashipathy MM, Roy A, Gagne JP, McDonald P, Gao P, Nonfoux L, Battaile KP, Johnson DK, Holmstrom ED, Poirier GG, Lovell S, Fehr AR J Virol. 2020 Nov 6. pii: JVI.01969-20. doi: 10.1128/JVI.01969-20. PMID:33158944[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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