Dynamics of theBacillus subtilisMin system

Abstract

SummaryDivision site selection is a vital process to ensure generation of viable offspring. In many rod-shaped bacteria a dynamic protein system, termed the Min system, acts as a central regulator of division site placement. The Min system is best studied in Escherichia coli where it shows a remarkable oscillation from pole to pole with a time-averaged density minimum at midcell. Several components of the Min system are conserved in the Gram-positive model organism Bacillus subtilis. However, in B. subtilis it is believed that the system forms a stationary bipolar gradient from the cell poles to midcell. Here, we show that the Min system of B. subtilis localizes dynamically to active sites of division, often organized in clusters. We provide physical modelling using measured diffusion constants that describe the observed enrichment of the Min system at the septum. Modelling suggests that the observed localization pattern of Min proteins corresponds to a dynamic equilibrium state. Our data provide evidence for the importance of ongoing septation for the Min dynamics, consistent with a major role of the Min system to control active division sites, but not cell pole areas.

Insights Into the Helical Shape Complex of Helicobacter pylori

“…In addition, recent studies have changed the assumption that nucleotide-independent scaffold proteins of the cytoskeleton to which bactofilins belong constitute rigid scaffolds ( Giacomelli et al, 2022 ). In B. subtilis , for example, the molecular function of DivIVA as a scaffolding platform undergoes modulation by other protein factors and is targeted to a specific molecular task that makes either a more stable complex dynamic or a more dynamic complex stable in response to protein–protein interactions ( Feddersen et al, 2021 ). To answer the question of the dynamics of CcmA in living cells using a cell biology approach, we investigated this with single-molecule tracking using the SMT software ( Rösch et al, 2018 ).…”

Control of protein-based pattern formation via guiding cues

“…As the required reactivation step is a non-equilibrium process that consumes energy, these gradients are maintained by a constant cycling of such proteins between the membrane and the cytosol, and therefore do not equilibrate by cytosolic diffusion. Since cytosolic gradients from opposing membrane points overlap at curved regions, one generally expects accumulation of inactive proteins in regions of high curvature (e.g., near the cell poles of elongated cells, including the rod-shaped E. coli [2], the C. elegans zygote [3], and Bacillus subtilis [128]) and a corresponding depletion of active proteins (Fig. 2f).…”

Control of protein-based pattern formation via guiding cues

“…Since BAR domains have a length of about 20 nm, the sensitivity of individual proteins to weakly curved surfaces is limited [124,127]. However, membrane curvature can facilitate the oligomerization of proteins into extended curved structures, which are capable of sensing membrane curvature on length scales larger than that of the individual protein [128]. Other important examples for such joint curvature sensing are dynamin, which forms helical collars around the thin neck during budding in yeast [129,130], and MreB, which assembles into filaments that orient along the highest membrane curvature [131,132].…”

“…As the required reactivation step is a non-equilibrium process that consumes energy, these gradients are maintained by a constant cycling of such proteins between the membrane and the cytosol, and therefore do not equilibrate by cytosolic diffusion. Since cytosolic gradients from opposing membrane points overlap at curved regions, one generally expects accumulation of inactive proteins in regions of high curvature (e.g., near the cell poles of elongated cells, including the rod-shaped E. coli [2], the C. elegans zygote [3], and Bacillus subtilis [128]) and a corresponding depletion of active proteins (Fig. 2f).…”