Cell Biology

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Science  13 Aug 2010:
Vol. 329, Issue 5993, pp. 731
DOI: 10.1126/science.329.5993.731-a

Occasionally, complex cellular structures previously thought to be devised by eukaryotes turn out to have functional counterparts in prokaryotes. In eukaryotes, mitosis is an intricate process regulated by many different proteins. It requires the assembly of a filamentous structure composed of microtubule polymers known as the mitotic spindle, which is used to segregate homologous chromosomes into daughter cells during cell division. Many bacteria use simpler approaches known as DNA partitioning systems to segregate their chromosomes.

Using super-resolution microscopy, Ptacin et al. have captured images of a mitotic spindle-like structure in the bacterium Caulobacter crescentus. Fluorescent labeling revealed that the ATPase ParA formed a narrow linear structure (green) stretching from pole to pole during segregation of the newly replicated DNA (purple) in C. crescentus. Additionally, electron micrographs of purified ParA confirmed that the protein could form linear polymers in vitro. The authors also identified another component of the partitioning system, TipN (yellow), which binds to ParA and is required for its function. Previous analogies have been made between bacterial chromosome segregation and eukaryotic mitosis; these findings narrow the gap between these two domains of life.

Nat. Cell Biol. 12, 791 (2010).

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