Elongationless start-stop elements are stress-resilient translation gates that are more repressive than uTranslons

Area of Science:

• Molecular Biology
• Gene Regulation
• Eukaryotic Translation

Background:

• Start-stop elements are regulatory sequences in 5' UTRs, featuring a start codon followed by a stop codon.
• Unlike canonical upstream Translons (uTranslons), start-stop elements inhibit elongation, conferring distinct regulatory properties.

Purpose of the Study:

• To conduct a comprehensive comparison of human start-stop elements and uTranslons.
• To elucidate the unique regulatory mechanisms and functional impacts of start-stop elements.

Main Methods:

• Genome-wide analysis of start-stop elements and uTranslons.
• Reporter assays to assess translational effects.
• Ribosome footprinting to analyze translation dynamics.

Main Results:

• Start-stop elements and uTranslons are found in similar gene sets (transcription factors, signaling molecules) with low transcript levels and short RNA half-lives.
• Genes with start-stop elements exhibit greater translational repression compared to those with uTranslons.
• A novel start-stop-specific mechanism involving repeat cycling between translation initiation, termination, ribosome splitting, and rejoining was identified, independent of global initiation state.

Conclusions:

• Start-stop elements represent a distinct class of translational regulators with enhanced repressive capabilities.
• The identified start-stop-specific ribosome cycling mechanism offers novel insights into eukaryotic translation control.
• The start-stop element in ATF4 modulates uTranslons, augmenting the regulatory model.