ATP-Driven Separation of Liquid Phase Condensates in Bacteria

Abstract

Liquid-liquid phase separated (LLPS) states are key to compartmentalise components in the absence of membranes, however it is unclear whether LLPS condensates are actively and specifically organized in the sub-cellular space and by which mechanisms. Here, we address this question by focusing on the ParAB S DNA segregation system, composed of a centromeric-like sequence (parS), a DNA-binding protein (ParB) and a motor (ParA). We show that parS-ParB associate to form nanometer-sized, round condensates. ParB molecules diffuse rapidly within the nucleoid volume, but display confined motions when trapped inside ParB condensates. Single ParB molecules are able to rapidly diffuse between different condensates, and nucleation is strongly favoured by parS. Notably, the ParA motor is required to prevent the fusion of ParB condensates. These results describe a novel active mechanism that splits, segregates and localises non-canonical LLPS condensates in the sub-cellular space.

Phase separation of polymer-bound particles induced by loop-mediated one dimensional effective long-range interactions

“…Such biological phase separation mechanisms often involve polymeric scaffolds like Ribonucleic acid (RNA) or Deoxyribonucleic acid (DNA) to bind the chemical species [4][5][6][7][8][9]. A prominent example may be the formation of localized protein-DNA complexes during bacteria DNA segregation due to the in vivo ParABS system [10][11][12][13][14][15]. Although the molecular components of this widely conserved segregation machinery have been clearly identified, their dynamical interplay and the mechanism that leads to the condensation of the complexes remain elusive.…”

Chaos, Order and Systematics in Evolution of the Genetic Code

“…Hydrogels (LLPS) appear to be incompletely characterized and somewhat difficult to analyze in prokaryotic systems [12][13][14]44,136]. We guess that hydrogel compartments are important for many bacterial processes including cell division, coupling of transcription and translation, nucleoid body maintenance and rearrangements, ion transport and signaling.…”

“…Although not yet as extensively studied, hydrogels and LLPS are also becoming recognized in prokaryotic systems [12][13][14]. In this paper, we explore hydrogel and LLPS compartments as drivers of the establishment of the genetic code.…”

“…LLPS compartments are disordered with complex interactions and components, so disruption of LLPS compartments is associated with human diseases such as cancers and neurological impairments [6][7][8][9][10][11][45][46][47]. So far as we can ascertain, prokaryotes utilize LLPS probably utilizing short disordered protein regions, RNAs and DNA [12][13][14].…”

Cytidine triphosphate promotes efficient ParB-dependent DNA condensation by facilitating one-dimensional spreading from parS

“…Moreover, and unexpectedly, parS sequences did not affect DNA condensation under these conditions (Taylor et al, 2015). Therefore the mechanism of ParB spreading and condensation, and in particular the molecular basis for the specific localisation around parS, has remained unclear despite extensive investigation in vivo, in vitro and in silico (Broedersz et al, 2014;Guilhas et al, 2020;Sanchez et al, 2015;.…”