title: Roles for replichores and macrodomains in segregation of the Escherichia coli chromosome.
abstract: Recent work has highlighted two main levels of global organization of the Escherichia coli chromosome. Macrodomains are large domains inferred from structural data consisting of loci showing the same intracellular positioning. Replichores, defined by base composition skews, coincide with the replication arms in normal cells. We used chromosome inversions to show that the dif site, which resolves chromosome dimers, only functions when located at the junction of the replichores, whatever their size. This is the first evidence that replichore polarization has a role in chromosome segregation. We also show that disruption of the Ter macrodomain provokes a cell-cycle defect independent from dimer resolution. This confirms the existence of the Ter macrodomain and suggests a role in chromosome dynamics.
authors.affiliation: Laboratoire de Microbiologie et de Génétique Moléculaire du CNRS, 118, route de Narbonne, 31062 Toulouse Cedex, France.
authors.forename: Christian
authors.initials: C
authors.lastname: Lesterlin
authors.forename: Romain
authors.initials: R
authors.lastname: Mercier
authors.forename: Frédéric
authors.initials: F
authors.lastname: Boccard
authors.forename: François-Xavier
authors.initials: FX
authors.lastname: Barre
authors.forename: François
authors.initials: F
authors.lastname: Cornet
mesh_terms: D002455:Cell Division / Q000235:genetics*; D007446:Chromosome Inversion / Q000235:genetics; D002874:Chromosome Mapping; D020090:Chromosome Segregation / Q000235:genetics / Q000502:physiology*; D002876:Chromosomes, Bacterial / Q000235:genetics*; D004261:DNA Replication / Q000235:genetics*; D004926:Escherichia coli / Q000166:cytology / Q000235:genetics*; D008957:Models, Genetic