title: Nuclear localization of the NS3 protein of hepatitis C virus and factors affecting the localization.
abstract: Subcellular localization of the NS2 and NS3 proteins of hepatitis C virus was analyzed. In stable Ltk transfectants inducibly expressing an NS2-NS3 polyprotein (amino acids [aa] 810 to 1463), processed full-size NS2 (aa 810 to 1026) was detected exclusively in a cytoplasmic membrane fraction. On the other hand, the other processed product, carboxy-truncated NS3 (NS3 deltaC1463; aa 1027 to 1463), was present in both cytoplasmic and nuclear fractions. To further analyze subcellular localization of NS3, NS3 deltaC1459 (aa 1027 to 1459), full-size NS3 (NS3F; aa 1027 to 1657), and both amino- and carboxy-truncated NS3 (NS3 deltaNdeltaC; aa 1201 to 1459) were expressed in HeLa cells by using a vaccinia virus-T7 hybrid expression system. NS3 deltaC1459 and NS3F accumulated in the nucleus as well as in the cytoplasm, exhibiting a dot-like staining pattern. On the other hand, NS3 deltaNdeltaC was localized predominantly in the cytoplasm, suggesting the presence of a nuclear localization signal(s) in the amino-terminal sequence of NS3. NS4A, a viral cofactor for the NS3 protease, inhibited nuclear transport of NS3 deltaC1459 and NS3F, with the latter inhibited to a lesser extent than was the former. Interestingly, wild-type p53 tumor suppressor augmented nuclear localization of NS3 deltaC1459 and NS3F, whereas mutant-type p53 inhibited nuclear localization and augmented cytoplasmic localization of NS3 deltaC1459. However, subcellular localization of NS3 deltaNdeltaC was not affected by either type of p53. Wild-type p53-mediated nuclear accumulation of NS3 deltaC1459 and NS3F was inhibited partially, but not completely, by coexpressed NS4A, with NS3F again affected less prominently than was NS3 deltaC1459.
authors.affiliation: Department of Microbiology, Kobe University School of Medicine, Hyogo, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Muramatsu
authors.forename: S
authors.initials: S
authors.lastname: Ishido
authors.forename: T
authors.initials: T
authors.lastname: Fujita
authors.forename: M
authors.initials: M
authors.lastname: Itoh
authors.forename: H
authors.initials: H
authors.lastname: Hotta
mesh_terms: D000818:Animals; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D015967:Gene Expression Regulation, Viral; D016158:Genes, p53; D006367:HeLa Cells; D016174:Hepacivirus / Q000235:genetics*; D006801:Humans; D051379:Mice; D009154:Mutation; D013347:Subcellular Fractions / Q000378:metabolism; D014162:Transfection; D017361:Viral Nonstructural Proteins / Q000235:genetics*; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases
chemical_list: D017361:Viral Nonstructural Proteins; C097010:NS2 protein, Hepatitis C virus; C084422:NS3 protein, hepatitis C virus; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases; C093542:NS4 protein, hepatitis C virus