Dogma-defying bacteria package DNA in unusual ways - Nature.com

Although histones are vital tools for maintaining chromosome structure and controlling gene activity in eukaryotes and microorganisms called archaea, for years it was widely assumed that they did not exist in bacteria.

“The fundamental composition of the chromatin and how gene expression works is very similar across eukaryotes and then you start wondering, ‘is that a frozen accident?’” he says.

Together with Luger and other collaborators, they studied the proteins from two species that can be readily grown in the laboratory: the pathogen Leptospira interrogans and a predatory bacterium called Bdellovibrio bacteriovorus.

This infiltrates larger bacteria and digests them from within, chopping up its prey’s DNA and proteins for use as building blocks to replicate itself.

It’s a striking finding, but it still isn’t clear whether that structure reflects how histones and DNA interact in the bacterial cells, or whether it’s an artefact of working with the isolated proteins in the laboratory, says Dame.

The bacterium is also known for having tightly packed DNA during its free-swimming phase, before it infects its prey, notes Géraldine Laloux, a microbiologist at the Catholic University of Louvain in Belgium.