title: Direct interaction between nucleolin and hepatitis C virus NS5B.
abstract: Hepatitis C virus (HCV) NS5B is an RNA-dependent RNA polymerase (RdRP), a central catalytic enzyme in HCV replication. While studying the subcellular localization of a NS5B mutant lacking the C-terminal membrane-anchoring domain, NS5Bt, we found that expression of the green fluorescent protein (GFP)-fused form was exclusively nucleolar. Interestingly, the distribution of endogenous nucleolin changed greatly in the cells expressing GFP-NS5B, with nucleolin colocalized with GFP-NS5B in perinuclear regions in addition to the nucleolus, suggesting that NS5B retains the ability to bind nucleolin. The interaction between nucleolin and NS5B was demonstrated by GST pull-down assay. GST pull-down assay results indicated that C-terminal region of nucleolin was important for its binding to NS5B. Scanning clustered alanine substitution mutants library of NS5B revealed two sites on NS5B that binds nucleolin. NS5B amino acids 208-214 and 500-506 were both found to be indispensable for the nucleolin binding. We reported that the latter sequence is essential for oligomerization of NS5B, which is a prerequisite for the RdRP activity. C-terminal nucleolin inhibited the NS5B RdRP activity in a dose-dependent manner. Taken together, this indicates the binding ability of nucleolin may be involved in NS5B functions.
authors.affiliation: Department of Molecular Oncology, Cancer Research Institute, Ishikawa 920-0934, Japan.
authors.forename: Masaaki
authors.initials: M
authors.lastname: Hirano
authors.forename: Shuichi
authors.initials: S
authors.lastname: Kaneko
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Yamashita
authors.forename: Hong
authors.initials: H
authors.lastname: Luo
authors.forename: Weiping
authors.initials: W
authors.lastname: Qin
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Shirota
authors.forename: Takahiro
authors.initials: T
authors.lastname: Nomura
authors.forename: Kenichi
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Seishi
authors.initials: S
authors.lastname: Murakami
mesh_terms: D000818:Animals; D019556:COS Cells; D049452:Green Fluorescent Proteins; D006367:HeLa Cells; D006801:Humans; D008164:Luminescent Proteins; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D012324:RNA-Dependent RNA Polymerase / Q000235:genetics / Q000378:metabolism; D017361:Viral Nonstructural Proteins / Q000235:genetics / Q000378:metabolism*; D000097796:Nucleolin
chemical_list: D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins; D009687:Nuclear Proteins; D010750:Phosphoproteins; D016601:RNA-Binding Proteins; D012324:RNA-Dependent RNA Polymerase; D017361:Viral Nonstructural Proteins; D000097796:Nucleolin; C087036:NS-5 protein, hepatitis C virus