RNA 3'-end mismatch excision by the severe acute respiratory syndrome coronavirus nonstructural protein nsp10/nsp14 exoribonuclease complex

• DOI: 10.1073/pnas.1201130109
• Publication Date: 2012-05-26T03:18:12Z
• Authors: Mickaël Bouvet; Isabelle Imbert; Lorenzo Subissi; Laure Gluais; Bruno Canard; Etienne Decroly
• Keywords: Exoribonuclease; Transcription; Five-prime cap

The replication/transcription complex of severe acute respiratory syndrome coronavirus is composed at least 16 nonstructural proteins (nsp1–16) encoded by the ORF-1a/1b. This includes replication enzymes commonly found in positive-strand RNA viruses, but also a set RNA-processing activities unique to some nidoviruses. nsp14 protein carries both exoribonuclease (ExoN) and (guanine-N7)-methyltransferase (N7-MTase) activities. ExoN activity ensures yet-uncharacterized function virus life cycle must be regulated avoid nonspecific degradation. In this work, we show that association nsp10 with stimulates >35-fold latter while playing no effect on N7-MTase activity. Nsp10 mutants unable interact are not proficient for activation. nsp10/nsp14 hydrolyzes double-stranded 3′ 5′ direction as well single mismatched nucleotide 3′-end mimicking an erroneous product. contrast, di-, tri-, longer unpaired ribonucleotide stretches, 3′-modified RNAs, resist nsp10/nsp14-mediated excision. addition activation nsp16-mediated 2′-O-MTase activity, activates processing potentially connected replicative mismatch repair mechanism.