Molecular biology and evolution of the bacterial intranuclear parasite Ca. Endonucleobacter

Abstract

Few bacteria are able to colonize eukaryotic host cells, and even fewer can invade organelles. Among the latter, those which colonize the nucleus (intranuclear bacteria) are a majority. The nucleus is considered as a replication niche that offers bacteria shelter, the opportunity to manipulate nuclear processes and nutrients in form of chromatin. Previous studies have suggested that intranuclear bacteria consume host chromatin, but this would inevitably lead to a collapse of their replication niche. Nuclear colonization has intrinsic risks for bacteria, as eukaryotic cells are able to sense nuclear deformation and respond to it activating apoptosis. Therefore, intranuclear bacteria must count on molecular mechanisms to prevent their host cells to shut down. Although many intranuclear bacteria have been visually characterized, little is known about how they colonize the nucleus, how they thrive within, and which effects they have on their host cells. [...] My findings challenge previous hypotheses about nutritional and survival strategies of intranuclear bacteria, and point out the genomic innovations that might define intranuclear lifestyle in bacteria.