The optimal strategy balancing risk and speed predicts DNA damage checkpoint override times

Area of Science:

• Cellular Biology
• Genetics
• Biophysics

Background:

• Cellular checkpoints are crucial for error correction during replication.
• Checkpoint override (adaptation, slippage, leakage) is vital but lacks quantitative understanding.
• Understanding checkpoint dynamics is key to fundamental laws of error correction.

Purpose of the Study:

• To develop a general theory for optimal checkpoint strategies.
• To balance the trade-off between replication risk and speed.
• To apply this theory to the DNA damage checkpoint (DDC) in budding yeast.

Main Methods:

• Derived a general theory for optimal checkpoint strategies, mathematically modeled as optimizing an absorbing boundary for a random walk.
• Developed novel reporters for quantifying double-strand DNA breaks (DSBs) and their repair.
• Measured DSB repair time distributions and survival probability after override.

Main Results:

• The theory accurately predicted override times as a function of DSB numbers.
• Precisely quantified DSB repair probabilities, including rare events.
• Demonstrated that override is more prevalent than previously assumed.

Conclusions:

• A first-principles calculation revealed underlying patterns in noisy override processes.
• The study provides a quantitative, system-level understanding of checkpoint override.
• Findings revise existing knowledge of DNA damage checkpoint adaptation.