TOP1 and TOP2 complementarily maintain DNA replication fork progression in vertebrates

During DNA replication, the topoisomerases TOP1 and TOP2 resolve topological stress associated with DNA unwinding. Based on their catalytic activities, TOP1 is believed to relieve positive supercoil ahead of the replication fork, whereas TOP2 primarily removes topological intertwines between sister chromatids behind the replication fork. As the replication fork rotates, these two TOPs are considered to function complementarily. While this functional interplay between TOP1 and TOP2 has been well