title: Stress-induced condensation of bacterial genomes results in re-pairing of sister chromosomes: implications for double strand DNA break repair.
abstract: Genome condensation is increasingly recognized as a generic stress response in bacteria. To better understand the physiological implications of this response, we used fluorescent markers to locate specific sites on Escherichia coli chromosomes following exposure to cytotoxic stress. We find that stress-induced condensation proceeds through a nonrandom, zipper-like convergence of sister chromosomes, which is proposed to rely on the recently demonstrated intrinsic ability of identical double-stranded DNA molecules to specifically identify each other. We further show that this convergence culminates in spatial proximity of homologous sites throughout chromosome arms. We suggest that the resulting apposition of homologous sites can explain how repair of double strand DNA breaks might occur in a mechanism that is independent of the widely accepted yet physiologically improbable genome-wide search for homologous templates. We claim that by inducing genome condensation and orderly convergence of sister chromosomes, diverse stress conditions prime bacteria to effectively cope with severe DNA lesions such as double strand DNA breaks.
authors.affiliation: From the Departments of Structural Biology and.
authors.forename: Nelia
authors.initials: N
authors.lastname: Shechter
authors.affiliation: From the Departments of Structural Biology and.
authors.forename: Liron
authors.initials: L
authors.lastname: Zaltzman
authors.affiliation: From the Departments of Structural Biology and.
authors.forename: Allon
authors.initials: A
authors.lastname: Weiner
authors.affiliation: Chemical Research Support, The Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Vlad
authors.initials: V
authors.lastname: Brumfeld
authors.affiliation: Chemical Research Support, The Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Eyal
authors.initials: E
authors.lastname: Shimoni
authors.affiliation: From the Departments of Structural Biology and.
authors.forename: Yael
authors.initials: Y
authors.lastname: Fridmann-Sirkis
authors.affiliation: From the Departments of Structural Biology and. Electronic address: avi.minsky@weizmann.ac.il.
authors.forename: Abraham
authors.initials: A
authors.lastname: Minsky
mesh_terms: D002876:Chromosomes, Bacterial / Q000235:genetics / Q000378:metabolism*; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair / Q000502:physiology*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D016680:Genome, Bacterial / Q000502:physiology*
keywords: Biophysics; DNA Damage; DNA Physical Chemistry; DNA Structure; Escherichia coli; Fluorescence; Homologous Recombination; RecA; Replication Forks