Reaction: nsp16 acts as a cap 2'-O-methyltransferase to modify SARS-CoV-1 mRNAs

- in pathway: Transcription of SARS-CoV-1 sgRNAs
The subgenomic mRNAs of SARS-CoV-1 coronavirus are presumed to be capped at their 5′ ends, based on studies of the mouse hepatitis virus (MHV) (Lai and Stohlman 1981) and the equine torovirus (van Vliet et al. 2002). The non-structural protein 16 (nsp16) acts as a 2'O-methyltransferase that converts coronavirus cap-0 to cap-1, which was first demonstrated with nsp16 cloned from the feline coronavirus (FCV) (Decroly et al. 2008). Cap-0 represents N7-methyl guanosine connected to the 5′ nucleotide through a 5′ to 5′ triphosphate linkage (also known as m7G cap or m7Gppp cap). Cap-1 is generated by an additional methylation on the 2′O position of the initiating nucleotide, and is also known as m7GpppNm. The non-structural protein 10 (nsp10) acts as an activator of nsp16 and is necessary for cap-1 synthesis (Bouvet et al. 2010, Decroly et al. 2011). Coronavirus RNAs with cap-1 are protected from IFIT-mediated interferon response, as IFITs recognize unmethylated 2'-O RNAs. IFITs are interferon-induced proteins with tetratricopeptide repeats that recognize unmethylated 2'-O RNAs and act to inhibit expression of virally encoded mRNAs (Menachery et al. 2014).
Reaction - small molecule participants:
S-adenosyl-L-homocysteine [cytosol]
S-adenosyl-L-methionine [cytosol]
Reactome.org reaction link: R-HSA-9684033

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Reaction input - small molecules:
S-adenosyl-L-methionine
ChEBI:15414
Reaction output - small molecules:
S-adenosyl-L-homocysteine
ChEBI:16680
Reactome.org link: R-HSA-9684033