Caulobacter chromosome in vivo configuration matches model predictions for a supercoiled polymer in a cell-like confinement

Sun-Hae Hong, Esteban Toro, Kim Mortensen, Mario A. Díaz de la Rosa, Sebastian Doniach, Lucy Shapiro, Andrew J. Spakowitz, Harley H. McAdams

    Research output: Contribution to journalJournal articleResearchpeer-review

    Abstract

    We measured the distance between fluorescent-labeled DNA loci of various interloci contour lengths in Caulobacter crescentus swarmer cells to determine the in vivo configuration of the chromosome. For DNA segments less than about 300 kb, the mean interloci distances, 〈r〉, scale as n0.22, where n is the contour length, and cell-to-cell distribution of the interloci distance r is a universal function of r/n0.22 with broad cell-to-cell variability. For DNA segments greater than about 300 kb, the mean interloci distances scale as n, in agreement with previous observations. The 0.22 value of the scaling exponent for short DNA segments is consistent with theoretical predictions for a branched DNA polymer structure. Predictions from Brownian dynamics simulations of the packing of supercoiled DNA polymers in an elongated cell-like confinement are also consistent with a branched DNA structure, and simulated interloci distance distributions predict that confinement leads to “freezing” of the supercoiled configuration. Lateral positions of labeled loci at comparable positions along the length of the cell are strongly correlated when the longitudinal locus positions differ by
    Original languageEnglish
    JournalProceedings of the National Academy of Sciences of the United States of America
    Volume110
    Issue number5
    Pages (from-to)1674-1679
    ISSN0027-8424
    DOIs
    Publication statusPublished - 2013

    Keywords

    • chromosome organization
    • DNA segregation
    • polymer conformation
    • computational modeling
    • bacterial genome

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