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Mol Cell. 2003 Oct;12(4):903-11.

Cleavage of the A site mRNA codon during ribosome pausing provides a mechanism for translational quality control.

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1
Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.

Abstract

Cells employ many mechanisms to ensure quality control during protein biosynthesis. Here, we show that, during the pausing of a bacterial ribosome, the mRNA being translated is cleaved at a site within or immediately adjacent to the A site codon. The extent of this A site mRNA cleavage is correlated with the extent of ribosome pausing as assayed by tmRNA-mediated tagging of the nascent polypeptide. Cleavage does not require tmRNA, the ribosomal alarmone (p)ppGpp, or bacterial toxins such as RelE which have been shown to stimulate a similar activity. Translation is required for cleavage, suggesting that the ribosome participates in the reaction in some fashion. When normal protein synthesis is compromised, A site mRNA cleavage and the tmRNA system provide a mechanism for reducing translational errors and the production of aberrant and potentially harmful polypeptides.

PMID:
14580341
[Indexed for MEDLINE]
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