nsp14 acts as a cap N7 methyltransferase to modify SARS-CoV-1 gRNA (plus strand)

Stable Identifier
R-HSA-9684017
Type
Reaction [uncertain]
Species
Homo sapiens
Related Species
Human SARS coronavirus
Compartment
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The genomic and subgenomic mRNAs of SARS-CoV-1 coronavirus, including the plus strand genomic RNA, are presumed to be capped at their 5′ end, based on studies of the mouse hepatitis virus (MHV) (Lai and Stohlman 1981) and the equine torovirus (van Vliet et al. 2002). Non-structural protein 14 (nsp14) acts as an RNA guanine-N7-methyltransferase (N7-MTase) that completes the synthesis of the cap-0 on the SARS-CoV-1 plus strand genomic RNA. Cap-0 represents N7-methyl guanosine connected to the 5′ nucleotide through a 5′ to 5′ triphosphate linkage, and is also known as m7G cap or m7Gppp cap. The N7-MTase domain maps to the carboxy-terminal part of nsp14 (Chen et al. 2009). Cap-0 formation requires three sequential reactions catalyzed by RNA triphosphatase (TPase), guanylyltransferase (GTase), and N7-MTase. There is no evidence that nsp14 possesses TPase and GTase activities, and no other SARS-CoV-1 proteins with these activities have been identified, so the identities of the enzymes that mediate these required steps remain unknown. Based on the study of the human coronavirus 229E, non-structural protein 13 (nsp13) may have a TPase activity in addition to its established helicase activity (Ivanov and Ziebuhr 2004).

Literature References
PubMed ID Title Journal Year
19208801 Functional screen reveals SARS coronavirus nonstructural protein nsp14 as a novel cap N7 methyltransferase

Chen, Y, Cai, H, Pan, J, Xiang, N, Tien, P, Ahola, T, Guo, D

Proc. Natl. Acad. Sci. U.S.A. 2009
Participants
Participant Of
Catalyst Activity
Catalyst Activity
Title
mRNA (guanine-N7-)-methyltransferase activity of RTC [double membrane vesicle viral factory outer membrane]
Physical Entity
Activity
Disease
Name Identifier Synonyms
severe acute respiratory syndrome 2945 SARS-CoV infection, SARS
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