Divergent tRNA-like element supports initiation, elongation, and termination of protein biosynthesis

The cricket paralysis virus internal ribosome entry site (IRES) can, in the absence of canonical initiation factors and initiator tRNA (Met-tRNAi), occupy the ribosomal P-site and assemble 80S ribosomes. Here we show that the IRES assembles mRNA-80S ribosome complexes by recruitment of 60S subunits...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2003-12, Vol.100 (26), p.15410-15415
Main Authors: Jan, E, Kinzy, T.G, Sarnow, P
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Base Sequence
binding proteins
Biochemistry
Biological Sciences
Codon, Terminator - genetics
Codons
Cricket paralysis virus
elongation factors
eukaryotic elongation factors
Gels
Genes, Reporter
insect viruses
Internal ribosome entry site
Luciferases - genetics
Messenger RNA
Open reading frames
Peptide Chain Elongation, Translational
Peptide Chain Initiation, Translational
Peptide Chain Termination, Translational
Peptide elongation factors
Peptides - chemistry
Peptides - metabolism
Protein Biosynthesis
Proteins
Ribonucleic acid
Ribosomes
Ribosomes - chemistry
Ribosomes - metabolism
RNA
RNA, Transfer - genetics
RNA, Transfer - metabolism
RNA, Transfer, Amino Acyl - genetics
RNA, Transfer, Amino Acyl - metabolism
Stop codon
Terminator codon
Transcription, Genetic
Transfer RNA
translation (genetics)
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Description
Summary:The cricket paralysis virus internal ribosome entry site (IRES) can, in the absence of canonical initiation factors and initiator tRNA (Met-tRNAi), occupy the ribosomal P-site and assemble 80S ribosomes. Here we show that the IRES assembles mRNA-80S ribosome complexes by recruitment of 60S subunits to preformed IRES-40S complexes. Addition of eukaryotic elongation factors eEF1A and eEF2 and aminoacylated elongator tRNAs resulted in the synthesis of peptides, implying that the IRES RNA itself mimics the function of Met-tRNAiin the P-site to trigger the first translocation step without peptide bond formation. IRES-80S complexes that contained a stop codon in the A-site recruited eukaryotic release factor eRF1, resulting in ribosome rearrangements in a surprisingly eEF2-dependent manner. Thus, this P-site-occupying IRES directs the assembly of 80S ribosomes, sets the translational reading frame, and mimics the functions of both Met-tRNAiand peptidyl tRNA to support elongation and termination.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.2535183100