Geometry of Braided DNA Dictates Supercoiling Partitioning

DNA braid geometry influences supercoiling partitioning by modulating torsional resistance, with small separations enabling fork rotation and larger separations creating barriers.

• Why it matters: Understanding how DNA's physical structure affects supercoiling is crucial for revealing mechanisms that regulate replication and manage topological stress in cells, which remains poorly understood.
• What they did: The study engineered DNA-braiding substrates mimicking replication conditions, measured braiding torques with an angular optical trap, and used Monte Carlo simulations to interpret how substrate geometry impacts supercoiling behavior.
• The result: Findings show that small DNA separations facilitate braiding and fork rotation, reducing torsional stress behind the fork, while larger separations hinder braiding, causing supercoiling to accumulate ahead, thus influencing replisome dynamics in vivo.