English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

In  Escherichia coli , prolonged translational arrest allows mRNA degradation into the A site of stalled ribosomes. The enzyme that cleaves the A-site codon is not known, but its activity requires RNase II to degrade mRNA downstream of the ribosome. This A-site mRNA cleavage process is thought to function in translation quality control because stalled ribosomes are recycled from A-site truncated transcripts by the tmRNA-SmpB “ribosome rescue” system. During rescue, the tmRNA-encoded ssrA peptide is added to the nascent chain, thereby targeting the tagged protein for degradation after release from the ribosome. Here, we examine the influence of A-site mRNA cleavage upon tmRNA-SmpB activity. Using a model transcript that undergoes stop-codon cleavage in response to inefficient translation termination, we quantify ssrA-peptide tagging of the encoded protein in cells that contain ( rnb +  ) or lack (Δ rnb ) RNase II. A-site mRNA cleavage is reduced approximately three-fold in Δ rnb  backgrounds, but the efficiency of ssrA-tagging is identical to that of  rnb   +  cells. Additionally, pulse-chase analysis demonstrates that paused ribosomes recycle from the test transcripts at similar rates in  rnb   +  and Δ rnb  cells. Together, these results indicate that A-site truncated transcripts are not required for tmRNA-SmpB-mediated ribosome rescue and suggest that A-site mRNA cleavage process may play a role in other recycling pathways.

A-Site mRNA Cleavage Is Not Required for tmRNA-Mediated ssrA-Peptide Tagging