Replication fork stalling by bulky DNA damage: localization at active origins and checkpoint modulation.

Area of Science:

• Molecular Biology
• Genetics
• Cell Biology

Background:

• DNA damage threatens genome integrity by blocking replication fork progression.
• The precise genomic locations, determinants, and in vivo consequences of replication fork stalling remain largely unknown.

Purpose of the Study:

• To investigate the genomic localization and regulation of replication fork stalling in yeast.
• To elucidate the role of origin activity and the intra-S-phase checkpoint in fork stalling and DNA damage bypass.

Main Methods:

• Utilized yeast as a model organism to study DNA damage response.
• Employed techniques to monitor replication fork progression and stalling in vivo.
• Investigated the impact of origin inactivation and checkpoint modulation on fork stalling.

Main Results:

• Bulky DNA damaging agents induce localized replication fork stalling at yeast replication origins.
• Stalling is dependent on proximal origin activity and modulated by the intra-S-phase checkpoint.
• Fork stalling precedes sister chromatid junction formation for DNA damage bypass; stalling is abrogated at inactivated origins.

Conclusions:

• Replication fork stalling at DNA adducts has a dual nature: checkpoint-independent arrest triggering sister chromatid junction formation and checkpoint-enhanced arrest at early origins.
• The intra-S-phase checkpoint plays a critical role in repressing late origin firing and enhancing fork stalling at early origins.
• These findings provide insights into the mechanisms of genome maintenance and DNA damage tolerance during replication.