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Published on: March 18, 2010
Active Control of Repetitive Structural Transitions between Replication Forks and Holliday Junctions by Werner
Soochul Shin1, Jinwoo Lee1, Sangwoon Yoo1
1Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea; Institute of Applied Physics, Seoul National University, Seoul 08826, Republic of Korea; National Center for Creative Research Initiatives, Seoul National University, Seoul 08826, Republic of Korea.
Abstract:
The reactivation of stalled DNA replication via fork regression invokes Holliday junction formation, branch migration, and the recovery of the replication fork after DNA repair or error-free DNA synthesis. The coordination mechanism for these DNA structural transitions by molecular motors, however, remains unclear. Here we perform single-molecule fluorescence experiments with Werner syndrome protein (WRN) and model replication forks. The Holliday junction is readily formed once the lagging arm is unwound, and migrated unidirectionally with 3.2 ± 0.03 bases/s velocity. The recovery of the replication fork was controlled by branch migration reversal of WRN, resulting in repetitive fork regression. The Holliday junction formation, branch migration, and migration direction reversal are all ATP dependent, revealing that WRN uses the energy of ATP hydrolysis to actively coordinate the structural transitions of DNA.
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