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Cell. 2014 Jun 19;157(7):1619-31. doi: 10.1016/j.cell.2014.04.041.

Programmed -1 frameshifting by kinetic partitioning during impeded translocation.

Author information

1
Max Planck Institute for Biophysical Chemistry, Department of Physical Biochemistry, 37077 Göttingen, Germany.
2
B.P. Konstantinov Petersburg Nuclear Physics Institute, Department of Molecular and Radiation Biophysics, 188300 Gatchina, Russia.
3
Max Planck Institute for Biophysical Chemistry, Department of Physical Biochemistry, 37077 Göttingen, Germany. Electronic address: rodnina@mpibpc.mpg.de.

Abstract

Programmed -1 ribosomal frameshifting (-1PRF) is an mRNA recoding event utilized by cells to enhance the information content of the genome and to regulate gene expression. The mechanism of -1PRF and its timing during translation elongation are unclear. Here, we identified the steps that govern -1PRF by following the stepwise movement of the ribosome through the frameshifting site of a model mRNA derived from the IBV 1a/1b gene in a reconstituted in vitro translation system from Escherichia coli. Frameshifting occurs at a late stage of translocation when the two tRNAs are bound to adjacent slippery sequence codons of the mRNA. The downstream pseudoknot in the mRNA impairs the closing movement of the 30S subunit head, the dissociation of EF-G, and the release of tRNA from the ribosome. The slippage of the ribosome into the -1 frame accelerates the completion of translocation, thereby further favoring translation in the new reading frame.

PMID:
24949973
DOI:
10.1016/j.cell.2014.04.041
[Indexed for MEDLINE]
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