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

Autor: Michelle Hawkins, Katie H. Jameson, Christian J. Rudolph
Jazyk: angličtina
Rok vydání: 2021
Předmět:
Zdroj: J Biol Chem
ISSN: 1083-351X
Popis: Data availability: Data not included in the manuscript or supporting information can be obtained on request by contacting the corresponding author (Michelle Hawkins: michelle.hawkins@york.ac.uk). Copyright © 2021 The Authors. 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 replisome to travel more than halfway around the chromosome. In this instance, replisome progression is blocked at the non-permissive interface of the Tus-ter complex, termination then occurs when a converging replisome meets the 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 complexes in vitro. We developed a termination mapping assay to measure leading strand replication fork progression and demonstrate that the DNA template is under-replicated by 15−24 bases when replication forks fuse at Tus-ter complexes. This gap could not be closed by the addition of lagging strand processing enzymes or by the inclusion of several helicases that promote DNA replication. Our results indicate that accurate fork fusion at Tus-ter barriers requires further enzymatic processing, highlighting large gaps that still exist in our understanding of the final stages of chromosome duplication and the evolutionary advantage of having a replication fork trap. The work was supported by Research Grant BB/N014995/1 and BB/N014863/1 from the Biotechnology and Biological Sciences Research Council to C. J. R. and M. H respectively.
Databáze: OpenAIRE