title: Initiation of heat-induced replication requires DnaA and the L-13-mer of oriC.
abstract: An upshift of 10 degrees C or more in the growth temperature of an Escherichia coli culture causes induction of extra rounds of chromosome replication. This stress replication initiates at oriC but has functional requirements different from those of cyclic replication. We named this phenomenon heat-induced replication (HIR). Analysis of HIR in bacterial strains that had complete or partial oriC deletions and were suppressed by F integration showed that no sequence outside oriC is used for HIR. Analysis of a number of oriC mutants showed that deletion of the L-13-mer, which makes oriC inactive for cyclic replication, was the only mutation studied that inactivated HIR. The requirement for this sequence was strictly correlated with Benham's theoretical stress-induced DNA duplex destabilization. oriC mutations at DnaA, FIS, or IHF binding sites showed normal HIR activation, but DnaA was required for HIR. We suggest that strand opening for HIR initiation occurs due to heat-induced destabilization of the L-13-mer, and the stable oligomeric DnaA-single-stranded oriC complex might be required only to load the replicative helicase DnaB.
authors.affiliation: Department of Biochemistry, Molecular Biology and Genetics, University of Extremadura, E06080-Badajoz, Spain.
authors.forename: Rocío
authors.initials: R
authors.lastname: González-Soltero
authors.forename: Emilia
authors.initials: E
authors.lastname: Botello
authors.forename: Alfonso
authors.initials: A
authors.lastname: Jiménez-Sánchez
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D002876:Chromosomes, Bacterial / Q000235:genetics*; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D048168:Escherichia coli K12 / Q000235:genetics / Q000502:physiology*; D015964:Gene Expression Regulation, Bacterial; D006358:Hot Temperature; D051738:Origin Recognition Complex / Q000235:genetics / Q000502:physiology*; D017354:Point Mutation
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C066312:DnaA protein, Bacteria; C114650:OriC chromosomal replication origin; D051738:Origin Recognition Complex