Treadmilling FtsZ polymers drive the directional movement of sPG-synthesis enzymes via a Brownian ratchet mechanism

Abstract

The FtsZ protein is a central component of the bacterial cell division machinery. It polymerizes at mid-cell and recruits more than 30 proteins to assemble into a macromolecular complex to direct cell wall constriction. FtsZ polymers exhibit treadmilling dynamics, driving the processive movement of enzymes that synthesize septal peptidoglycan (sPG). Here, we combine theoretical modelling with single-molecule imaging of live bacterial cells to show that FtsZ’s treadmilling drives the directional movement of sPG enzymes via a Brownian ratchet mechanism. The processivity of the directional movement depends on the binding potential between FtsZ and the sPG enzyme, and on a balance between the enzyme’s diffusion and FtsZ’s treadmilling speed. We propose that this interplay may provide a mechanism to control the spatiotemporal distribution of active sPG enzymes, explaining the distinct roles of FtsZ treadmilling in modulating cell wall constriction rate observed in different bacteria.

How Teichoic Acids Could Support a Periplasm in Gram-Positive Bacteria, and Let Cell Division Cheat Turgor Pressure

“…In Bacillus subtilis D ranged from 0.2 to 0.5 μm 2 s –1 for proteins with 2–12 transmembrane segments ( Lucena et al, 2018 ). Particularly relevant to cell division, the transpeptidases PBP3 (FtsI) in E. coli , and PBP2b in B. subtilis had virtually identical diffusion coefficients of 0.041 and 0.038 μm 2 s –1 ( McCausland et al, 2021 ). These values are lower than ranges quoted above, perhaps because the tall PBPs are interacting with the PGW.…”

Dynamic localisation of DamX regulates bacterial filamentation and division during UPEC dispersal from host cells

“…Since mEos3.2-DamX is assembled at multiple sites along filaments, we wondered whether septal PG (sPG 34 ) synthesis also occurs at multiple sites at the same time. To test this, we pulse-labelled filaments during reversal to detect regions of sPG synthesis with an OregonGreen488-labelled Fluorescent D-amino acid (OGDA) 35,36 .…”

“…4h). Since mEos3.2-DamX is assembled at multiple sites along filaments, we wondered whether septal PG (sPG 34 ) synthesis also occurs at multiple sites at the same time.…”

A Dynamic Network of Proteins Facilitate Cell Envelope Biogenesis in Gram-Negative Bacteria

“…The elongasome complex ( Figure 5 ) contains the components of generalised peptidoglycan synthesis ( Figure 1 ), but we postulate as have others, based on our bioinformatic analysis and the literature ( Figure 3 ), that the complex also contains class C PBP D, D-carboxypeptidases and lytic transglycosylases to modify peptidoglycan structure and prime it for attachment with new peptidoglycan [ 1 , 45 ]. This model contains the core monofunctional class B transpeptidase PBP2 which inserts its single transmembrane helix into the seven transmembrane helices of RodA, activating it as a glycosyltransferase [ 46 ].…”