This mode of action may be limited to rod-shaped bacteria that have two separate PG-machineries, as opposed to cocci, which have only one PG-machinery that is capable of finalizing division in cells with inhibited FtsZ dynamics 17.Īt a late stage of membrane constriction, but prior to inner membrane fusion, FtsZ disassembles from midcell, indicating the possible existence of an upper limit of ring curvature 6, 9. The treadmilling filaments guide and regulate septal peptidoglycan (PG-) production and ingrowth, leading to septation 16. In rod-shaped model bacteria such as Escherichia coli and Bacillus subtilis, FtsZ is believed to organize into short bundles of filaments, roughly 100 nm in length 11, 12, that treadmill at the septum with a circumferential velocity in the order of 20–30 nm s −1 13– 15. “d” in c– e, and h– l indicates cell diameter Black dots represent individual data points, bars represent mean with error bars representing S.D. Black arrows point to examples of FtsZ trajectories. Corresponding kymographs are shown adjacent to each image.
l Snapshots of epifluorescence (EPI) images from time-lapse series of FtsZ-GFP dynamics in drug-treated cells. coli cells ( h) untreated or ( i– k) treated with drugs. h– k Structured illumination microscopy (SIM) images of FtsZ-GFP in E. Whiskers on the box plots encompass 95.5% of the distribution. Boxes represent S.D., with red lines indicating mean. Conditions for proper division ring placement are met when width 0.05. Standing cells were trapped in a vertical position in micron-sized holes in agarose pads created using micron-sized pillars. Green dotted ring in the cells represents the FtsZ-ring (red arrow). b Schematic representation of cell placement for imaging. For clarity, only FtsZ (gray dots), it’s membrane tethers, FtsA and ZipA (blue dots), and the membrane (brown) are shown. a Simplified cartoon showing FtsZ treadmilling at the division plane of an E. Midcell FtsZ-ring assembly is unaffected by increased cell diameter. Based on our results, we propose that the underlying membrane geometry is not a deciding factor for FtsZ cluster maintenance and dynamics in vivo. We use stimulated emission depletion (STED) nanoscopy to show that FtsZ clusters in sculpted cells maintain the same dimensions as their wild-type counterparts. This approach allowed us to examine FtsZ behavior in engineered Z-squares and Z-hearts. Here, to establish a framework for examining geometrical influences on proper Z-ring assembly and dynamics, we sculpted Escherichia coli cells into unnatural shapes using division- and cell wall-specific inhibitors in a micro-fabrication scheme. FtsZ assembles into a heterogeneous structure coined the Z-ring due to its resemblance to a ring confined by the midcell geometry.
It has been implicated in acting as a scaffolding protein for other division proteins, a force generator during constriction, and more recently, as an active regulator of septal cell wall production. FtsZ is the main regulator of bacterial cell division.