Hydrolases;
Acting on peptide bonds (peptidases);
Serine endopeptidases
Reaction(IUBMB)
Selective hydrolysis of -Xaa-Xaa!Yaa- bonds in which each of the Xaa can be either Arg or Lys and Yaa can be either Ser or Ala
Comment
Known from classical flaviviruses (yellow fever, dengue fever). The functional viral peptidase is part of the NS2B protein. Catalytic His, Asp and Ser residues are arranged as in chymotrypsin, but flavivrin is the type example of peptidase family S7.
Cleavage of the dengue virus polyprotein at the NS3/NS4A and NS4B/NS5 junctions is mediated by viral protease NS2B-NS3, whereas NS4A/NS4B may be processed by a cellular protease.
Cleavage at a novel site in the NS4A region by the yellow fever virus NS2B-3 proteinase is a prerequisite for processing at the downstream 4A/4B signalase site.
