Multiple Parallel Pathways of Translation Initiation on the CrPV IRES

Alexey Petrov, Rosslyn Grosely, Jin Chen, Seán E. O'Leary, Joseph D. Puglisi

Research output: Contribution to journalArticlepeer-review

39 Scopus citations


The complexity of eukaryotic translation allows fine-tuned regulation of protein synthesis. Viruses use internal ribosome entry sites (IRESs) to minimize or, like the CrPV IRES, eliminate the need for initiation factors. Here, by exploiting the CrPV IRES, we observed the entire process of initiation and transition to elongation in real time. We directly tracked the CrPV IRES, 40S and 60S ribosomal subunits, and tRNA using single-molecule fluorescence spectroscopy and identified multiple parallel initiation pathways within the system. Our results distinguished two pathways of 80S:CrPV IRES complex assembly that produce elongation-competent complexes. Following 80S assembly, the requisite eEF2-mediated translocation results in an unstable intermediate that is captured by binding of the elongator tRNA. Whereas initiation can occur in the 0 and +1 frames, the arrival of the first tRNA defines the reading frame and strongly favors 0 frame initiation. Overall, even in the simplest system, an intricate reaction network regulates translation initiation.

Original languageEnglish (US)
Pages (from-to)92-103
Number of pages12
JournalMolecular cell
Issue number1
StatePublished - Apr 7 2016
Externally publishedYes

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology


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