RNA-cDNA hybrids mediate transposition via different mechanisms.

Area of Science:

• Molecular Biology
• Genetics
• Genomics

Background:

• Retrotransposons comprise a significant portion of eukaryotic genomes.
• Dysregulation of retrotransposons is linked to genomic instability and human diseases.
• RNA-DNA hybrids, or R-loops, are emerging regulators of retrotransposon activity.

Purpose of the Study:

• To investigate the mechanism by which RNA-DNA hybrids influence Ty1 retrotransposon mobility.
• To identify genetic factors regulating R-loop accumulation and its effect on Ty1 elements.

Main Methods:

• Utilized a targeted genetic screen in yeast to identify mutants affecting Ty1 mobility.
• Characterized RNA-DNA hybrid structures (duplex vs. triplex) in specific yeast mutants.
• Assessed the role of Rad52 and RNase H enzymes in R-loop-mediated retrotransposon mobilization.

Main Results:

• Identified the rnh1Δ rad27Δ yeast mutant with elevated Ty1 cDNA-associated RNA-DNA hybrids and increased Ty1 mobility.
• Demonstrated that duplex RNA-DNA hybrids promote Ty1 mobility in a Rad52-dependent manner.
• Showed that triplex RNA-DNA hybrids promote Ty1 mobility independently of Rad52.

Conclusions:

• Elevated RNA-DNA hybrids, particularly duplex structures, enhance Ty1 mobility through a Rad52-dependent pathway.
• Triplex RNA-DNA hybrids enhance Ty1 mobility via a Rad52-independent pathway.
• These findings elucidate novel mechanisms by which R-loops regulate retrotransposon activity and genome stability.