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Mol Cell. 2017 May 18;66(4):558-567.e4. doi: 10.1016/j.molcel.2017.04.023.

Conditional Switch between Frameshifting Regimes upon Translation of dnaX mRNA.

Author information

1
Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany.
2
Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany. Electronic address: rodnina@mpibpc.mpg.de.

Abstract

Ribosome frameshifting during translation of bacterial dnaX can proceed via different routes, generating a variety of distinct polypeptides. Using kinetic experiments, we show that -1 frameshifting predominantly occurs during translocation of two tRNAs bound to the slippery sequence codons. This pathway depends on a stem-loop mRNA structure downstream of the slippery sequence and operates when aminoacyl-tRNAs are abundant. However, when aminoacyl-tRNAs are in short supply, the ribosome switches to an alternative frameshifting pathway that is independent of a stem-loop. Ribosome stalling at a vacant 0-frame A-site codon results in slippage of the P-site peptidyl-tRNA, allowing for -1-frame decoding. When the -1-frame aminoacyl-tRNA is lacking, the ribosomes switch into -2 frame. Quantitative mass spectrometry shows that the -2-frame product is synthesized in vivo. We suggest that switching between frameshifting routes may enrich gene expression at conditions of aminoacyl-tRNA limitation.

KEYWORDS:

dnaX; kinetics; programmed ribosome frameshifting; protein synthesis; recoding; tRNA abundance; translation pausing; translation regulation

PMID:
28525745
DOI:
10.1016/j.molcel.2017.04.023
[Indexed for MEDLINE]
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