Multiple pathways regulate 3' overhang generation at S. cerevisiae telomeres.

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Telomere ends possess 3' G-strand overhangs, essential for telomerase regulation.
• The precise mechanisms governing telomere end processing and overhang generation remain incompletely understood.

Purpose of the Study:

• To elucidate the roles of Sae2 and Sgs1 helicase in telomere end processing in Saccharomyces cerevisiae.
• To investigate the interplay between Sae2, Sgs1, Exo1, and Dna2 in telomere maintenance.

Main Methods:

• Utilized an inducible short telomere assay in Saccharomyces cerevisiae.
• Employing genetic deletions (sae2Δ, sgs1Δ, sae2Δ sgs1Δ) to assess protein function.
• Investigated the contribution of Exo1 and Dna2 exonucleases to telomere processing.

Main Results:

• Sae2 and Sgs1 helicase govern distinct yet complementary pathways for telomere nucleolytic processing.
• Sae2's function is dependent on serine 267 phosphorylation.
• Exo1 exonuclease activity in telomere processing and elongation requires either Sgs1 or Sae2.
• Dna2 acts redundantly with Exo1, suggesting a supportive role for Sgs1 activity.
• Combined Sae2 and Sgs1 activities are critical for both telomere length maintenance and G-strand overhang generation.

Conclusions:

• Sae2 and Sgs1 are key regulators of telomere processing, controlling both length and overhang formation.
• The findings reveal a complex network of proteins, including Exo1 and Dna2, cooperating in telomere maintenance.
• Understanding these pathways provides insight into telomere stability and its implications for cellular aging and disease.