N-terminal domains of putative helicases of flavi- and pestiviruses may be serine proteases.
Recently we tentatively identified, by sequence comparison, central domains of the NS3 proteins of flaviviruses and the respective portion of the pestivirus polyprotein as RNA helicases (A.E.G. et al., submitted). Alignment of the N-proximal domains of the same proteins revealed conservation of short sequence stretches resembling those around the catalytic Ser, His and Asp residues of chymotrypsin-like proteases. A statistically significant similarity has been detected between the sequences of these domains and those of the C-terminal serine protease domains of alphavirus capsid proteins. It is suggested that flavivirus NS3 and the respective pestivirus protein contain at least two functional domains, the N-proximal protease and the C-proximal helicase one. The protease domain is probably involved in the processing of viral non-structural proteins.
Gorbalenya
A E
AE
Institute of Poliomyelitis and Viral Encephalitides, USSR Academy of Medical Sciences, Moscow region.
Donchenko
A P
AP
Koonin
E V
EV
Blinov
V M
VM
D000595:Amino Acid Sequence; D005416:Flavivirus / Q000201:enzymology* / Q000235:genetics; D008969:Molecular Sequence Data; D010576:Pestivirus / Q000201:enzymology* / Q000235:genetics; D020365:RNA Helicases; D012316:RNA Nucleotidyltransferases / Q000235:genetics*; D012697:Serine Endopeptidases / Q000235:genetics*; D017361:Viral Nonstructural Proteins; D014764:Viral Proteins / Q000235:genetics*; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases
D020365:RNA Helicases; D012316:RNA Nucleotidyltransferases; D012697:Serine Endopeptidases; D017361:Viral Nonstructural Proteins; D014764:Viral Proteins; C060028:NS3 protein, flavivirus; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases