Structural highlights
Function
POLN_HEVPA Methyltransferase: Displays a capping enzyme activity. This function is necessary since all viral RNAs are synthesized in the cytoplasm, and host capping enzymes are restricted to the nucleus. The enzymatic reaction involves a covalent link between 7-methyl-GMP and the methyltransferase, whereas eukaryotic capping enzymes form a covalent complex only with GMP. Methyltransferase catalyzes transfer of a methyl group from S-adenosylmethionine to GTP and GDP to yield m(7)GTP or m(7)GDP. GDP is a better substrate than GTP. This enzyme also displays guanylyltransferase activity to form a covalent complex, methyltransferase-m(7)GMP, from which 7-methyl-GMP is transferred to the mRNA to create the cap structure.[UniProtKB:Q81862] Y-domain: Indispensable for virus replication.[UniProtKB:Q81862] Putative protease: May participate in the processing of polyprotein pORF1 and capsid protein ORF2, possibly together with cellular proteases. Inhibits induction of IFN-beta by MDA5 and RIG-I pathways and down-regulates the expression of MDA5.[UniProtKB:Q81862] NTPase/helicase: Multi-functional protein that exhibits NTPase and RNA unwinding activities (By similarity). Hydrolyzes all NTPs efficiently and unwinds RNA duplexes containing 5' overhangs (By similarity). Possesses a sequence independent RNA-5'-triphosphatase (RTPase) activity suggestive of its role in forming viral cap structure. Participates also in viral genome replication, RNA translocation and genome packaging/unpackaging (By similarity).[UniProtKB:P29324][UniProtKB:Q81862] RNA-directed RNA polymerase: Plays an essential role in the virus replication (By similarity). Binds to the 3'-end of the genomic RNA to initiate viral replication (By similarity).[UniProtKB:Q81862][UniProtKB:Q9WC28]
