Biochemistry and medicinal chemistry of the dengue virus protease

The dengue virus contains a single-stranded RNA genome, which is replicated by the translation mechanisms of the host in conjunction with the viral RNA-dependent RNA polymerase. Replication of dengue virus requires the formation of virus-specific biomolecular machinery at the rough endoplasmatic reticulum that is known as the replication complex and consists of vesicular membrane structures. The protease of dengue virus is devoid of cysteine residues and therefore does not contain disulfide bonds. There are also no indications of essential posttranslational modifications. These properties make a heterologous expression of the protein in bacteria relatively straightforward. The first generation of dengue virus protease inhibitors was derived from the cleavage sites of the viral polyprotein. Peptidic compounds that combine these peptide-based inhibitors with highly reactive electrophiles can target the catalytically active serine and occupy all important recognition sites of the protease as confirmed by X-ray crystal structure analysis. Promising alternative to in vitro assays of dengue protease acitivity would be cell-based assays, in which the binding of inhibitors to the enzyme is studied under native conditions.