Mechanism of ribosome recruitment by hepatitis C IRES RNA.
Many viruses and certain cellular mRNAs initiate protein synthesis from a highly structured RNA sequence in the 5' untranslated region, called the internal ribosome entry site (IRES). In hepatitis C virus (HCV), the IRES RNA functionally replaces several large initiation factor proteins by directly recruiting the 43S particle. Using quantitative binding assays, modification interference of binding, and chemical and enzymatic footprinting experiments, we show that three independently folded tertiary structural domains in the IRES RNA make intimate contacts to two purified components of the 43S particle: the 40S ribosomal subunit and eukaryotic initiation factor 3 (eIF3). We measure the affinity and demonstrate the specificity of these interactions for the first time and show that the high affinity interaction of IRES RNA with the 40S subunit drives formation of the IRES RNA-40S-eIF3 ternary complex. Thus, the HCV IRES RNA recruits 43S particles in a mode distinct from both eukaryotic cap-dependent and prokaryotic ribosome recruitment strategies, and is architecturally and functionally unique from other large folded RNAs that have been characterized to date.
Department of Molecular Biophysics and Biochemistry and Howard Hughes Medical Institute, Yale University, New Haven, Connecticut 06520-8114, USA.
J S
JS
Kieft
K
K
Zhou
R
R
Jubin
J A
JA
Doudna
D000818:Animals; D001483:Base Sequence; D020134:Catalytic Domain; D018387:Codon, Initiator; D017931:DNA Primers / Q000737:chemistry; D039621:Eukaryotic Initiation Factor-3; D016174:Hepacivirus / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010448:Peptide Initiation Factors / Q000737:chemistry / Q000378:metabolism; D010710:Phosphates / Q000737:chemistry; D017354:Point Mutation; D017955:Poliovirus / Q000235:genetics; D016133:Polymerase Chain Reaction; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012367:RNA, Viral / Q000032:analysis* / Q000235:genetics / Q000378:metabolism*; D011817:Rabbits; D012156:Reticulocytes / Q000378:metabolism; D006163:Ribonuclease T1 / Q000235:genetics / Q000378:metabolism; D012270:Ribosomes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
D018387:Codon, Initiator; D017931:DNA Primers; D039621:Eukaryotic Initiation Factor-3; D010448:Peptide Initiation Factors; D010710:Phosphates; D012333:RNA, Messenger; D012367:RNA, Viral; D006163:Ribonuclease T1; C035638:thiophosphoric acid