Translation of poly(A) tails leads to precise mRNA cleavage

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• The
• nonstop/no-go
• decay pathway involves mRNA cleavage triggered by poly(A) tail translation, but its mechanism and prevalence are unclear.

Purpose of the Study:

• To investigate the mechanism of mRNA cleavage associated with ribosome stalling at 3' ends of decay intermediates.
• To identify conditions leading to ribosome stalling and subsequent mRNA degradation.

Main Methods:

• Ribosome profiling of short mRNA footprints in yeast lacking exosome function.
• Analysis of mRNA cleavage sites relative to ribosome stalling positions and reading frames.

Main Results:

• mRNA cleavage was observed hundreds of nucleotides upstream of ribosome stalling, predominantly in one reading frame, suggesting proximity to the ribosome.
• Ribosome stalling occurred with as few as three consecutive lysine codons, but significant degradation was not observed.
• Endonucleolytic cleavage was detected at premature polyadenylation sites (polylysine), and ribosome rescue depended on Dom34.

Conclusions:

• Decay-triggering endonucleolytic cleavage is closely linked to ribosome activity.
• Ribosome stalling due to specific codons or premature polyadenylation may play a role in cellular processes like development and disease.
• Dom34-dependent ribosome rescue is critical at sites of premature polyadenylation.