title: Hepatitis C virus internal ribosome entry site-mediated translation is stimulated by specific interaction of independent regions of human La autoantigen.
abstract: The human La autoantigen has been shown to interact with the internal ribosome entry site (IRES) of hepatitis C virus (HCV) in vitro. Using a yeast three-hybrid system, we demonstrated that, in addition to full-length La protein, both N- and C-terminal halves were able to interact with HCV IRES in vivo. The exogenous addition of purified full-length and truncated La proteins in rabbit reticulocyte lysate showed dose-dependent stimulation of HCV IRES-mediated translation. However, an additive effect was achieved adding the terminal halves together in the reaction, suggesting that both might play critical roles in achieving full stimulatory activity of the full-length La protein. Using computational analysis, three-dimensional structures of the RNA recognition motifs (RRM) of the La protein were independently modeled. Of the three putative RRMs, RRM2 was predicted to have a good binding pocket for the interaction with the HCV IRES around the GCAC motif near the initiator AUG and RRM3 binds perhaps in a different location. This observation was further investigated by the filter-binding and toe-printing assays. The results presented here strongly suggest that both the N- and C-terminal halves can interact independently with the HCV IRES and are involved in stimulating internal initiation of translation.
authors.affiliation: Department of Microbiology and Cell Biology and the Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India.
authors.forename: Renuka
authors.initials: R
authors.lastname: Pudi
authors.forename: Saraswathi
authors.initials: S
authors.lastname: Abhiman
authors.forename: Narayanaswamy
authors.initials: N
authors.lastname: Srinivasan
authors.forename: Saumitra
authors.initials: S
authors.lastname: Das
mesh_terms: D000595:Amino Acid Sequence; D001324:Autoantigens; D016174:Hepacivirus / Q000235:genetics*; D006526:Hepatitis C / Q000821:virology*; D006801:Humans; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D014176:Protein Biosynthesis; D017434:Protein Structure, Tertiary; D012367:RNA, Viral / Q000235:genetics / Q000378:metabolism; D012261:Ribonucleoproteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D012270:Ribosomes / Q000737:chemistry / Q000821:virology*; D020798:Two-Hybrid System Techniques; D015003:Yeasts; D000097585:SS-B Antigen
chemical_list: D001324:Autoantigens; D012367:RNA, Viral; D012261:Ribonucleoproteins; D000097585:SS-B Antigen