title: The adenine-rich tract in the 5ʹ-end of the hepatitis C virus ORF encodes a peptide regulating the binding of the C protein to RNA.
abstract: Hepatitis C virus (HCV) core (C) protein is thought to bind to viral RNA before it undergoes oligomerization leading to RNA encapsidation. Details of these events are so far unknown. The 5ʹ-terminal C protein coding sequence that includes an adenine (A)-rich tract is a part of an internal ribosome entry site (IRES). This nucleotide sequence but not the corresponding protein sequence is needed for proper initiation of translation of viral RNA by an IRES-dependent mechanism. In this study, we examined the importance of this sequence for the ability of the C protein to bind to viral RNA. Serially truncated C proteins with deletions from 10 up to 45 N-terminal amino acids were expressed in Escherichia coli, purified and tested for binding to viral RNA by a gel shift assay. The results showed that truncation of the C protein from its N-terminus by more than 10 amino acids abolished almost completely its expression in E. coli. The latter could be restored by adding a tag to the N-terminus of the protein. The tagged proteins truncated by 15 or more amino acids showed an anomalous migration in SDS-PAGE. Truncation by more than 20 amino acids resulted in a complete loss of ability of tagged C protein to bind to viral RNA. These results provide clues to the early events in the C protein - RNA interactions leading to C protein oligomerization, RNA encapsidation and virion assembly.
  
  
  BACKGROUND
  hepatitis C virus; core protein; RNA binding.
authors.affiliation: National institute of Biomedical Genomics, P. O.: N. S. S., 2nd Floor, Kalyani, West Bengal-741251, India. sc2@nibmg.ac.in
authors.forename: S
authors.initials: S
authors.lastname: Chinnaswamy
authors.forename: W B
authors.initials: WB
authors.lastname: Lott
mesh_terms: D020121:5' Untranslated Regions; D000225:Adenine / Q000737:chemistry / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D016174:Hepacivirus / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D016366:Open Reading Frames; D010455:Peptides / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D012367:RNA, Viral / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014758:Viral Core Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D020121:5' Untranslated Regions; D010455:Peptides; D012367:RNA, Viral; D014758:Viral Core Proteins; D000225:Adenine