Stress-induced Condensation of Bacterial Genomes Results in Re-pairing of Sister Chromosomes

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 str...

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Bibliographic Details
Published in:The Journal of biological chemistry 2013-08, Vol.288 (35), p.25659-25667
Main Authors: Shechter, Nelia, Zaltzman, Liron, Weiner, Allon, Brumfeld, Vlad, Shimoni, Eyal, Fridmann-Sirkis, Yael, Minsky, Abraham
Format: Article
Language:English
Subjects:
Biophysics
DNA Damage
DNA Physical Chemistry
DNA Structure
Escherichia coli
Fluorescence
Homologous Recombination
RecA
Replication Forks
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Summary: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. Background: Genome-wide homology search is inconsistent with the emerging view of bacterial genome morphology. Results: Stress-induced genome condensation proceeds through nonrandom convergence of sister chromosomes that culminates in spatial proximity of homologous sites. Conclusion: Chromosome convergence enables repair of double strand DNA breaks. Significance: Exposure to diverse stressful conditions primes bacteria to cope with detrimental DNA lesions.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M113.473025