An internal polypyrimidine-tract-binding protein-binding site in the hepatitis C virus RNA attenuates translation, which is relieved by the 3'-untranslated sequence

Virology. 1999 Feb 15;254(2):288-96. doi: 10.1006/viro.1998.9541.

Abstract

Hepatitis C virus (HCV) RNA binds to several cellular proteins, which may regulate translation or replication of viral RNA. One of these is polypyrimidine tract-binding protein (PTB), which binds to the 5'-untranslated region (UTR) and the 3'-end 98 nucleotides (nt) (X region) of HCV RNA. Both of these PTB-binding sites regulate HCV translation. In this study, we further investigated the nature of PTB binding on HCV RNA. UV cross-linking studies using HeLa cell extracts and a recombinant PTB showed that the PTB-5'-UTR binding was much weaker than the PTB-3'-UTR binding. Unexpectedly, we found an even stronger PTB-binding site in the core-protein-coding region of HCV RNA. The binding domain was mapped to the 3'-end of this region, which contains a pyrimidine-rich sequence highly conserved among HCV isolates. Using a set of synthetic HCV RNAs with or without this sequence in in vitro translation studies, we showed that the PTB-binding sequence in the core-coding region strongly inhibited translation of HCV RNA. This inhibition was relieved by the presence of the X region at the 3'-end. Furthermore, the previously reported translational enhancement by the HCV 3'-UTR was more pronounced when this PTB-binding site was present in the RNA. These results suggest that PTB binding to an internal site of HCV RNA provides another mechanism for regulation of HCV translation.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Base Sequence
  • Binding Sites / genetics
  • Chromosome Mapping
  • DNA-Binding Proteins / metabolism*
  • HeLa Cells
  • Hepacivirus / genetics*
  • Humans
  • Molecular Sequence Data
  • Polypyrimidine Tract-Binding Protein
  • Protein Biosynthesis*
  • RNA, Viral / metabolism
  • RNA-Binding Proteins / metabolism*

Substances

  • DNA-Binding Proteins
  • RNA, Viral
  • RNA-Binding Proteins
  • Polypyrimidine Tract-Binding Protein