Termination of DNA replication at Tus-ter barriers results in under-replication of template DNA

Abstract

The complete and accurate duplication of genomic information is vital to maintain genome stability in all domains of life. In Escherichia coli, replication termination, the final stage of the duplication process, is confined to the ‘replication fork trap’ region by multiple unidirectional fork barriers formed by the binding of Tus protein to genomic ter sites. Termination typically occurs away from Tus-ter complexes, but they become part of the fork fusion process when a delay to one replisome allows the second to travel more than halfway around the chromosome. In this instance, replisome progression is blocked at the non-permissive interface of Tus-ter and termination occurs when a converging replisome meets the non-permissive interface. To investigate the consequences of replication fork fusion at Tus-ter complexes, we established a plasmid-based replication system where we could mimic the termination process at Tus-ter in vitro.