Spatial organization of a replicating bacterial chromosome

Idit Anna Berlatzky, Alex Rouvinski, Sigal Ben-Yehuda*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

70 Scopus citations


Emerging evidence indicates that the global organization of the bacterial chromosome is defined by its physical map. This architectural understanding has been gained mainly by observing the localization and dynamics of specific chromosomal loci. However, the spatial and temporal organization of the entire mass of newly synthesized DNA remains elusive. To visualize replicated DNA within living cells, we developed an experimental system in the bacterium Bacillus subtilis whereby fluorescently labeled nucleotides are incorporated into the chromosome as it is being replicated. Here, we present the first visualization of replication morphologies exhibited by the bacterial chromosome. At the start of replication, newly synthesized DNA is translocated via a helical structure from midcell toward the poles, where it accumulates. Next, additionally synthesized DNA forms a second, visually distinct helix that interweaves with the original one. In the final stage of replication, the space between the two helices is filled up with the very last synthesized DNA. This striking geometry provides insight into the three-dimensional conformation of the replicating chromosome.

Original languageAmerican English
Pages (from-to)14136-14140
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number37
StatePublished - 16 Sep 2008


  • Bacillus subtilis
  • Bacterial cell biology
  • DNA replication
  • Nucleoid
  • Replisome


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