Down-regulation of translation driven by hepatitis C virus internal ribosomal entry site by the 3' untranslated region of RNA.
The genome of hepatitis C virus (HCV) is a single-stranded RNA of positive polarity that has a poly(U/C) tract followed by a highly conserved 98-nt sequence, termed the X region, in the 3' untranslated region (UTR). To investigate the effect of the 3'UTR on the HCV translation that depends on the internal ribosomal entry site (IRES), we prepared a deletion HCV RNA, MA delta, that lacked the RNA region from nt 1286 to 8785. A series of MA delta RNAs that differ in the primary structure of their 3'UTR, were generated and examined for their translation efficiencies in reticulocyte lysates. Deletion of the poly(U/C) tract and/or stem-loop structure (SL) 3 region of 3'X resulted in enhancement of the translation efficiency. Translation of MA delta RNA was inhibited by the addition of recombinant polypyrimidine tract-binding protein (PTB). A similar inhibition by PTB, however, was observed when an RNA lacking the poly(U/C) tract or SL3 region was used. The inhibitory effect by PTB was not obvious for MA delta (1041) RNA composed of nt 1 to 1041 but MA delta (8928) RNA composed of nt 1 to 1285 and nt 8786 to 8928. These results suggest that the observed down-regulation of HCV translation by the 3'UTR is mediated by some host factor(s) other than PTB, and that a PTB site for inhibition resides in the coding sequence of nt 1042 to 8928 of MA delta RNA.
Murakami
K
K
Department of Microbiology, Institute of Medical Science, University of Tokyo, Tokyo, Japan.
Abe
M
M
Kageyama
T
T
Kamoshita
N
N
Nomoto
A
A
D020413:3' Untranslated Regions; D000818:Animals; D015536:Down-Regulation; D016174:Hepacivirus / Q000235:genetics*; D010442:Peptide Chain Initiation, Translational; D038941:Polypyrimidine Tract-Binding Protein; D011131:Polyribonucleotides / Q000378:metabolism; D014176:Protein Biosynthesis; D020871:RNA Stability; D020038:RNA, Spliced Leader / Q000235:genetics; D012367:RNA, Viral / Q000096:biosynthesis / Q000235:genetics*; D016601:RNA-Binding Proteins / Q000378:metabolism; D012261:Ribonucleoproteins / Q000378:metabolism; D017384:Sequence Deletion
D020413:3' Untranslated Regions; D011131:Polyribonucleotides; D020038:RNA, Spliced Leader; D012367:RNA, Viral; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; D038941:Polypyrimidine Tract-Binding Protein