A new role for monomeric ParA/Soj in chromosome dynamics in <i>Bacillus subtilis</i>

Roberts, David M.

doi:10.1002/mbo3.1344

Cited by 2 publications

(1 citation statement)

References 82 publications

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“…Since either loop-extrusion or origin segregation seems to suffice for these bacteria, these mechanisms might play partially over-lapping roles during bacterial chromosome segregation. On the other hand, in fast growth media, C. crescentus [27,28] and Bacillus subtilis [29,30,31] depend on both a ParABS system and loop-extrusion to achieve accurate chromosome segregation. Therefore, in all these species the relative contributions of these biophysical mechanisms to chromosome segregation, as well as their interplay with entropic forces, remain unclear.…”

Section: Introductionmentioning

confidence: 99%

Loop-extruders alter bacterial chromosome topology to direct entropic forces for segregation

Harju

Teeseling

Broedersz

2023

Preprint

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Entropic forces have been argued to allow bacteria to segregate their chromosomes during replication. In many bacterial species, however, specifically evolved mechanisms, such as loop-extruding SMC complexes and the ParABS origin segregation system, are required for chromosome segregation, suggesting that entropic forces alone may be insufficient. The interplay between and the relative contributions of these segregation mechanisms remain unclear. Here, we develop a biophysical model showing that purely entropic forces actually inhibit bacterial chromosome segregation until late replication stages. By contrast, we find that loop-extruders loaded at the origins of replication, as found in many bacterial species, alter the effective topology of the chromosome, thereby redirecting and enhancing entropic forces to enable accurate chromosome segregation concurrent with replication. In addition, our model indicates that locally acting origin separation mechanisms, such as the ParABS system, cannot redirect segregation-inhibiting entropic forces. We confirm our predictions with 3D simulations of a replicating polymer: purely entropic forces do not allow for concurrent replication and segregation; entropic forces steered by loop-extruders loaded at the origin lead to robust, global chromosome segregation; and origin separation alone is effective at early replication stages, but does not fully segregate terminal regions. Together, our results illustrate how entropic forces and loop-extrusion play synergistic roles during bacterial chromosome segregation, whereas locally acting mechanisms serve a complementary function.

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Section: Introductionmentioning

confidence: 99%

Loop-extruders alter bacterial chromosome topology to direct entropic forces for segregation

Harju

Teeseling

Broedersz

2023

Preprint

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Rok from B. subtilis: Bridging genome structure and transcription regulation

Erkelens,

van Erp,

Meijer

et al. 2024

Molecular Microbiology

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Bacterial genomes are folded and organized into compact yet dynamic structures, called nucleoids. Nucleoid orchestration involves many factors at multiple length scales, such as nucleoid‐associated proteins and liquid–liquid phase separation, and has to be compatible with replication and transcription. Possibly, genome organization plays an intrinsic role in transcription regulation, in addition to classical transcription factors. In this review, we provide arguments supporting this view using the Gram‐positive bacterium Bacillus subtilis as a model. Proteins BsSMC, HBsu and Rok all impact the structure of the B. subtilis chromosome. Particularly for Rok, there is compelling evidence that it combines its structural function with a role as global gene regulator. Many studies describe either function of Rok, but rarely both are addressed at the same time. Here, we review both sides of the coin and integrate them into one model. Rok forms unusually stable DNA–DNA bridges and this ability likely underlies its repressive effect on transcription by either preventing RNA polymerase from binding to DNA or trapping it inside DNA loops. Partner proteins are needed to change or relieve Rok‐mediated gene repression. Lastly, we investigate which features characterize H‐NS‐like proteins, a family that, at present, lacks a clear definition.

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A new role for monomeric ParA/Soj in chromosome dynamics in Bacillus subtilis

Cited by 2 publications

References 82 publications

Loop-extruders alter bacterial chromosome topology to direct entropic forces for segregation

Loop-extruders alter bacterial chromosome topology to direct entropic forces for segregation

Rok from B. subtilis: Bridging genome structure and transcription regulation

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