title: Inhibition and restart of initiation of chromosome replication: effects on exponentially growing Escherichia coli cells.
abstract: Escherichia coli strains in which initiation of chromosome replication could be specifically blocked while other cellular processes continued uninhibited were constructed. Inhibition of replication resulted in a reduced growth rate and in inhibition of cell division after a time period roughly corresponding to the sum of the lengths of the C and D periods. The division inhibition was not mediated by the SOS regulon. The cells became elongated, and a majority contained a centrally located nucleoid with a fully replicated chromosome. The replication block was reversible, and restart of chromosome replication allowed cell division and rapid growth to resume after a time delay. After the resumption, the septum positions were nonrandomly distributed along the length axis of the cells, and a majority of the divisions resulted in at least one newborn cell of normal size and DNA content. With a transient temperature shift, a single synchronous round of chromosome replication and cell division could be induced in the population, making the constructed system useful for studies of cell cycle-specific events. The coordination between chromosome replication, nucleoid segregation, and cell division in E. coli is discussed.
authors.affiliation: Department of Microbiology, Uppsala University, Sweden.
authors.forename: R
authors.initials: R
authors.lastname: Bernander
authors.forename: T
authors.initials: T
authors.lastname: Akerlund
authors.forename: K
authors.initials: K
authors.lastname: Nordström
mesh_terms: D002455:Cell Division; D002876:Chromosomes, Bacterial; D004261:DNA Replication; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development; D013014:SOS Response, Genetics