Esc2 promotes telomere stability in response to DNA replication stress

Area of Science:

• Genetics
• Molecular Biology
• Genomics

Background:

• Telomeres are challenging genomic regions for DNA replication due to secondary structures and nucleoprotein complexes.
• Cellular responses to DNA replication stalling within telomeres are not well understood due to analytical challenges.

Purpose of the Study:

• To investigate the cellular response to a defined DNA replication fork stalling event at a telomere.
• To identify factors that protect telomeres from DNA replication stress and subsequent genomic instability.

Main Methods:

• Utilized the site-specific 'Tus/Ter' system to induce DNA replication barriers at a telomere.
• Performed molecular genetic analysis of the defined fork-stalling event.
• Conducted a genome-wide genetic screen to identify relevant proteins.

Main Results:

• Identified the SUMO-like domain protein, Esc2, as crucial for limiting genome rearrangements at telomeres.
• Demonstrated that Mph1 helicase and homologous recombination machinery drive telomeric rearrangements upon fork stalling.
• Showed that chromosomal context impacts cellular responses to stalled replication forks.

Conclusions:

• Esc2 acts as a protective factor at telomeric loci against DNA replication stress.
• Understanding telomere-specific responses to replication stress is vital for maintaining genome stability.
• This study reveals mechanisms that limit chromosomal instability induced by replication fork stalling at telomeres.