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Publication Abstract from PubMed

The hepatitis C virus (HCV) is a flavivirus replicating in the cytoplasm of infected cells. The HCV genome is a single stranded RNA encoding a polyprotein cleaved by cellular and viral proteases into 10 products. While the structural proteins core, envelope protein 1 (E1) and E2 build up the virus particle, most nonstructural (NS) proteins are required for RNA replication. One of the least studied proteins is NS2, which is composed of a C-terminal cytosolic protease domain and a highly hydrophobic N-terminal domain. It is assumed that the latter is composed of 3 trans-membrane segments (TMS) that tightly attach NS2 to intracellular membranes. Taking advantage of a system to study HCV assembly in a hepatoma cell line, in this study we performed a detailed characterization of NS2 with respect to its role for particle assembly. In agreement with an earlier report (Jones et al., J Virol, 81, 8374-8383, 2007) we demonstrate that the protease domain, but not its enzymatic activity is required for infectious virus production. We also show that serine 168 in NS2 implicated in phosphorylation and stability of this protein is dispensable for virion formation. Furthermore, we determined the NMR structure of the first TMS of NS2 and show that the N-terminal segment (aa 3 to 11) forms a putative flexible helical element connected to a stable alpha-helix (aa 12 to 21) that includes an absolutely conserved helix side in genotype 1b. By using this structure and the amino acid conservation as a guide for a functional study, we determined the contribution of individual amino acid residues in TMS1 for HCV assembly. We identified several residues that are critical for virion formation, most notably a central glycine residue at position 10 of TMS1. Finally, we demonstrate that mutations in NS2 blocking HCV assembly can be rescued by trans-complementation.

Structural and functional characterization of non-structural protein 2 for its role in hepatitis C virus assembly.,Jirasko V, Montserret R, Appel N, Janvier A, Eustachi L, Brohm C, Steinmann E, Pietschmann T, Penin F, Bartenschlager R J Biol Chem. 2008 Jul 21. PMID:18644781^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.