Flipped over U: structural basis for dsRNA cleavage by the SARS-CoV-2 endoribonuclease.
Nucleic Acids Res
; 50(14): 8290-8301, 2022 08 12.
Article
in English
| MEDLINE | ID: covidwho-1931874
ABSTRACT
Coronaviruses generate double-stranded (ds) RNA intermediates during viral replication that can activate host immune sensors. To evade activation of the host pattern recognition receptor MDA5, coronaviruses employ Nsp15, which is a uridine-specific endoribonuclease. Nsp15 is proposed to associate with the coronavirus replication-transcription complex within double-membrane vesicles to cleave these dsRNA intermediates. How Nsp15 recognizes and processes dsRNA is poorly understood because previous structural studies of Nsp15 have been limited to small single-stranded (ss) RNA substrates. Here we present cryo-EM structures of SARS-CoV-2 Nsp15 bound to a 52nt dsRNA. We observed that the Nsp15 hexamer forms a platform for engaging dsRNA across multiple protomers. The structures, along with site-directed mutagenesis and RNA cleavage assays revealed critical insight into dsRNA recognition and processing. To process dsRNA Nsp15 utilizes a base-flipping mechanism to properly orient the uridine within the active site for cleavage. Our findings show that Nsp15 is a distinctive endoribonuclease that can cleave both ss- and dsRNA effectively.
Full text:
Available
Collection:
International databases
Database:
MEDLINE
Main subject:
Endoribonucleases
/
COVID-19
Limits:
Humans
Language:
English
Journal:
Nucleic Acids Res
Year:
2022
Document Type:
Article
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