Movement of Replicating DNA through a Stationary Replisome

Abstract

We found that DNA is replicated at a central stationary polymerase, and each replicated region moves away from the replisome. In Bacillus subtilis, DNA polymerase is predominantly located at or near midcell. When replication was blocked in a specific chromosomal region, that region was centrally located with DNA polymerase. Upon release of the block, each copy of the duplicated region was located toward opposite cell poles, away from the central replisome. In a roughly synchronous population of cells, a region of chromosome between origin and terminus moved to the replisome prior to duplication. Thus, the polymerase at the replication forks is stationary, and the template is pulled in and released outward during duplication. We propose that B. subtilis, and probably many bacteria, harness energy released during nucleotide condensation by a stationary replisome to facilitate chromosome partitioning.