Dampening DNA damage checkpoint signalling via coordinated BRCT domain interactions

Area of Science:

• Molecular Biology
• Cell Biology
• Genetics

Background:

• DNA damage triggers checkpoint signaling to protect genome integrity.
• Checkpoint activation inhibits cell cycle progression and DNA replication.
• Down-regulation of checkpoint signaling is crucial for cellular proliferation.

Purpose of the Study:

• To elucidate the molecular mechanisms of phosphatase-independent checkpoint dampening.
• To characterize the role of Slx4-Rtt107 repair scaffolds in counteracting checkpoint adaptors.
• To establish the requirements for a novel mode of checkpoint regulation.

Main Methods:

• Engineering a minimal multi-BRCT-domain (MBD) module.
• Investigating synergistic interactions with lesion-specific phospho-sites (Ddc1 and H2A).
• Analyzing the recruitment of Dpb11-Slx4-Rtt107 and MBD via a two-site-docking mechanism.
• Examining MBD interactions with Mus81 nuclease.

Main Results:

• A minimal multi-BRCT-domain (MBD) module was engineered to mimic Slx4-Rtt107 function.
• MBD synergistically interacts with phospho-sites on Ddc1 and H2A, displacing Rad9.
• A cooperative 'two-site-docking' mechanism facilitates the recruitment of checkpoint regulators.
• MBD interacts with Mus81, indicating coordination between checkpoint dampening and DNA repair.

Conclusions:

• A novel phosphatase-independent mechanism for checkpoint dampening involves Slx4-Rtt107 and its MBD module.
• Cooperative binding via a 'two-site-docking' mechanism is key to displacing checkpoint adaptors like Rad9.
• BRCT domain interactions orchestrate spatio-temporal coordination of DNA damage signaling and repair pathways.