Mn 2+ coordinates Cap-0-RNA to align substrates for efficient 2′- O -methyl transfer by SARS-CoV-2 nsp16
Autor: | Nicole L. Inniss, George Minasov, Courtney M. Daczkowski, Andrew D. Mesecar, Karla J. F. Satchell, Paul Hoover, Joseph S. Brunzelle, Monica Rosas-Lemus, Ludmilla Shuvalova |
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Rok vydání: | 2021 |
Předmět: |
Models
Molecular S-Adenosylmethionine Ribonucleotide Methyltransferase viruses RNA Stability Viral Nonstructural Proteins Crystallography X-Ray medicine.disease_cause Biochemistry Insert (molecular biology) Substrate Specificity 0302 clinical medicine Structural Biology Catalytic Domain skin and connective tissue diseases Research Articles Coronavirus 0303 health sciences biology Chemistry Recombinant Proteins Infectious Diseases RNA Viral Research Article Signal Transduction RNA Caps Stereochemistry Methylation 03 medical and health sciences Virology medicine Humans Amino Acid Sequence RNA Messenger Molecular Biology 030304 developmental biology Manganese Messenger RNA SARS-CoV-2 fungi COVID-19 Active site RNA STKE Research Articles Methyltransferases Cell Biology respiratory tract diseases body regions biology.protein Nucleic Acid Conformation 030217 neurology & neurosurgery |
Zdroj: | Science Signaling |
ISSN: | 1937-9145 1945-0877 |
DOI: | 10.1126/scisignal.abh2071 |
Popis: | Efficient RNA capping by the SARS-CoV-2 methyltransferase requires metal ions and a unique four-residue insert. Uniquely coronavirus Virally encoded 2′-O-methyltransferases catalyze the last step in the capping of viral RNAs, which protects the RNAs from degradation and prevents them from triggering host defenses. Minasov et al. report structures of the SARS-CoV-2 methyltransferase, a heterodimeric complex of the enzyme nsp16 and its coactivator nsp10, in complex with a short, capped RNA (instead of the RNA cap analogs used to generate previous structures), the methyl donor SAM, and divalent metal cations. The metal ions and a four-residue insert of nsp16 were important for precisely aligning the RNA substrate in the active site for efficient catalysis. This insert is present in coronavirus but not in mammalian methyltransferases, suggesting this site as a potential target for the design of coronavirus-specific methyltransferase inhibitors. Capping of viral messenger RNAs is essential for efficient translation, for virus replication, and for preventing detection by the host cell innate response system. The SARS-CoV-2 genome encodes the 2′-O-methyltransferase nsp16, which, when bound to the coactivator nsp10, uses S-adenosylmethionine (SAM) as a donor to transfer a methyl group to the first ribonucleotide of the mRNA in the final step of viral mRNA capping. Here, we provide biochemical and structural evidence that this reaction requires divalent cations, preferably Mn2+, and a coronavirus-specific four-residue insert. We determined the x-ray structures of the SARS-CoV-2 2′-O-methyltransferase (the nsp16-nsp10 heterodimer) in complex with its reaction substrates, products, and divalent metal cations. These structural snapshots revealed that metal ions and the insert stabilize interactions between the capped RNA and nsp16, resulting in the precise alignment of the ribonucleotides in the active site. Comparison of available structures of 2′-O-methyltransferases with capped RNAs from different organisms revealed that the four-residue insert unique to coronavirus nsp16 alters the backbone conformation of the capped RNA in the binding groove, thereby promoting catalysis. This insert is highly conserved across coronaviruses, and its absence in mammalian methyltransferases makes this region a promising site for structure-guided drug design of selective coronavirus inhibitors. |
Databáze: | OpenAIRE |
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