Chromatin organization and radio resistance in the bacterium Gemmata obscuriglobus

Arnon Lieber, Andrew Leis, Ariel Kushmaro, Abraham Minsky, Ohad Medalia

Research output: Contribution to journalArticlepeer-review

47 Scopus citations

Abstract

The organization of chromatin has a major impact on cellular activities, such as gene expression. For bacteria, it was suggested that the spatial organization of the genetic material correlates with transcriptional levels, implying a specific architecture of the chromosome within the cytoplasm. Accordingly, recent technological advances have emphasized the organization of the genetic material within nucleoid structures. Gemmata obscurigtobus, a member of the phylum Planctomycetes, exhibits a distinctive nucleoid structure in which chromatin is encapsulated within a discrete membrane-bound compartment. Here, we show that this soil and freshwater bacterium tolerates high doses of UV and ionizing radiation. Cryoelectron tomography of frozen hydrated sections and electron microscopy of freeze-substituted cells have indicated a more highly ordered condensed-chromatin organization in actively dividing and stationary-phase G. obscurigtobus cells. These three-dimensional analyses revealed a complex network of double membranes that engulf the condensed DNA. Bioinformatics analysis has revealed the existence of a putative component involved in nonhomologous DNA end joining that presumably plays a role in maintaining chromatin integrity within the bacterium. Thus, our observations further support the notion that packed chromatin organization enhances radiation tolerance.

Original languageEnglish
Pages (from-to)1439-1445
Number of pages7
JournalJournal of Bacteriology
Volume191
Issue number5
DOIs
StatePublished - 1 Mar 2009

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