Ribosome Biogenesis Modulates Ty1 Copy Number Control in Saccharomyces cerevisiae

Area of Science:

• Molecular Biology
• Genetics
• Yeast Biology

Background:

• Transposons, like Ty1 in yeast, can disrupt host genomes.
• Organisms employ mechanisms, such as Ty1 copy number control (CNC), to limit transposition.
• CNC in Saccharomyces cerevisiae involves the restriction factor p22, derived from the GAG capsid gene.

Purpose of the Study:

• To investigate novel factors influencing Ty1 copy number control (CNC).
• To explore the role of ribosome biogenesis in regulating Ty1 transposition.
• To understand the molecular mechanisms linking ribosome function to transposon regulation.

Main Methods:

• Secondary screening of Ty1 cofactors.
• Analysis of Ty1 mobility in yeast mutants.
• Quantification of Ty1 mRNA and internal Ty1i transcripts.
• Western blotting to assess p22 protein levels and half-life.
• Transcriptomic analysis.
• Assessment of Gag complex assembly and RNA packaging.

Main Results:

• The gene LOC1, involved in RNA localization and ribosome biogenesis, was identified as affecting Ty1 mobility.
• Mutants affecting ribosome biogenesis (rps0bΔ, rpl7aΔ) exhibited CNC-specific defects similar to loc1Δ.
• Altered Ty1 and Ty1i RNA levels were observed, with a relative increase in Ty1i RNA.
• Increased p22 protein levels and half-life were detected in loc1Δ mutants.
• Defective Gag complex assembly and Ty1 RNA packaging occurred in loc1Δ mutants.

Conclusions:

• Defective ribosome biogenesis enhances Ty1 CNC by increasing p22 levels.
• This suggests a novel link between virus-like particle assembly, cytoplasmic environment, and cellular stress response.
• Ribosome biogenesis is critical for effective Ty1 copy number control.