Flavivirus non-structural protein 5 methyltransferase (NS5 MTase) (NS5 MTase)

The Flavivirus non-structural protein 5 (NS5) methyltransferase is a multifunctional enzyme essential for the maturation and stability of viral mRNA (UniProt P29990). Located at the N-terminus of the large NS5 protein, it catalyzes two distinct methylation steps: N7-guanine methylation and 2'-O-ribose methylation of the viral RNA cap structure (Ray et al., 2006). These modifications are crucial for efficient viral protein translation and allow the virus to evade the host's innate immune system by mimicking cellular mRNA, thereby avoiding detection by pattern recognition receptors like RIG-I (Brecher et al., 2015). Given its highly conserved nature across the Flaviviridae family—including pathogens such as Dengue, Zika, and West Nile viruses—this enzyme is a primary target for the development of broad-spectrum antivirals (Dong et al., 2008). Therapeutic strategies typically involve small molecules that competitively inhibit the S-adenosyl-L-methionine (SAM) binding pocket or target the RNA-binding site to halt viral replication (PubChem CID 439535). However, achieving high selectivity over human host methyltransferases remains a significant challenge in drug design (Brecher et al., 2015).

Other names

NS5 N-terminal domainFlavivirus RNA methyltransferaseNS5 capping enzymeNS5-MTaseFlavivirus RNA 2'-O-methyltransferase

Competitive inhibition of the S-adenosyl-L-methionine (SAM) binding site or the RNA-binding site to prevent viral RNA capping, thereby inhibiting viral translation and replication (Dong et al., 2008).