title: Replication and segregation of an Escherichia coli chromosome with two replication origins.
abstract: Characterized bacteria, unlike eukaryotes and some archaea, initiate replication bidirectionally from a single replication origin contained within a circular or linear chromosome. We constructed Escherichia coli cells with two WT origins separated by 1 Mb in their 4.64-Mb chromosome. Productive bidirectional replication initiated synchronously at both spatially separate origins. Newly replicated DNA from both origins was segregated sequentially as replication progressed, with two temporally and spatially separate replication termination events. Replication initiation occurred at a cell volume identical to that of cells with a single WT origin, showing that initiation control is independent of cellular and chromosomal oriC concentration. Cells containing just the ectopic origin initiated bidirectional replication at the expected cell mass and at the normal cellular location of that region. In all strains, spatial separation of sister loci adjacent to active origins occurred shortly after their replication, independently of whether replication initiated at the normal origin, the ectopic origin, or both origins.
authors.affiliation: Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom.
authors.forename: Xindan
authors.initials: X
authors.lastname: Wang
authors.forename: Christian
authors.initials: C
authors.lastname: Lesterlin
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Reyes-Lamothe
authors.forename: Graeme
authors.initials: G
authors.lastname: Ball
authors.forename: David J
authors.initials: DJ
authors.lastname: Sherratt
mesh_terms: D002453:Cell Cycle; D002876:Chromosomes, Bacterial; D004926:Escherichia coli / Q000235:genetics*; D005434:Flow Cytometry; D018741:Replication Origin