A three-dimensional ParF meshwork assembles through the nucleoid to mediate plasmid segregation.

Genome segregation is a fundamental step in the life cycle of every cell. Most bacteria rely on dedicated DNA partition proteins to actively segregate chromosomes and low copy-number plasmids. Here, by employing super resolution microscopy, we establish that the ParF DNA partition protein of the ParA family assembles into a three-dimensional meshwork that uses the nucleoid as a scaffold and periodically shuttles between its poles.

Chromosome segregation in Archaea mediated by a hybrid DNA partition machine.

Eukarya and, more recently, some bacteria have been shown to rely on a cytoskeleton-based apparatus to drive chromosome segregation. In contrast, the factors and mechanisms underpinning this fundamental process are underexplored in archaea, the third domain of life. Here we establish that the archaeon Sulfolobus solfataricus harbors a hybrid segrosome consisting of two interacting proteins, SegA and SegB, that play a key role in genome segregation in this organism.

Soj antagonizes Spo0A activation of transcription in Bacillus subtilis.

The ParA family protein Soj appears to negatively regulate sporulation in Bacillus subtilis by inhibiting transcription from promoters that are activated by phosphorylated Spo0A. We tested in vitro Soj inhibition of Spo0A-independent variants of a promoter that Soj inhibited (PspoIIG). Transcription from the variants was less sensitive to Soj inhibition, suggesting that inhibition of wild-type PspoIIG was linked to transcription activation by Spo0A.