A second type of N7-guanine RNA cap methyltransferase in an unusual locus of a large RNA virus genome.
Nucleic Acids Res
; 50(19): 11186-11198, 2022 10 28.
Article
em En
| MEDLINE
| ID: mdl-36265859
ABSTRACT
The order Nidovirales is a diverse group of (+)RNA viruses, with a common genome organization and conserved set of replicative and editing enzymes. In particular, RNA methyltransferases play a central role in mRNA stability and immune escape. However, their presence and distribution in different Nidovirales families is not homogeneous. In Coronaviridae, the best characterized family, two distinct methytransferases perform methylation of the N7-guanine and 2'-OH of the RNA-cap to generate a cap-1 structure (m7GpppNm). The genes of both of these enzymes are located in the ORF1b genomic region. While 2'-O-MTases can be identified for most other families based on conservation of both sequence motifs and genetic loci, identification of the N7-guanine methyltransferase has proved more challenging. Recently, we identified a putative N7-MTase domain in the ORF1a region (N7-MT-1a) of certain members of the large genome Tobaniviridae family. Here, we demonstrate that this domain indeed harbors N7-specific methyltransferase activity. We present its structure as the first N7-specific Rossmann-fold (RF) MTase identified for (+)RNA viruses, making it remarkably different from that of the known Coronaviridae ORF1b N7-MTase gene. We discuss the evolutionary implications of such an appearance in this unexpected location in the genome, which introduces a split-off in the classification of Tobaniviridae.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Capuzes de RNA
/
Nidovirales
Limite:
Humans
Idioma:
En
Revista:
Nucleic Acids Res
Ano de publicação:
2022
Tipo de documento:
Article