Z-ring membrane anchors associate with cell wall synthases to initiate bacterial cell division

Abstract

During the transition from elongation to septation, Escherichia coli establishes a ring-like peptidoglycan growth zone at the future division site. This preseptal peptidoglycan synthesis does not require the cell division-specific peptidoglycan transpeptidase PBP3 or most of the other cell division proteins, but it does require FtsZ, its membrane-anchor ZipA and at least one of the bi-functional transglycosylase-transpeptidases, PBP1A or PBP1B. Here we show that PBP1A and PBP1B interact with ZipA and localise to preseptal sites in cells with inhibited PBP3. ZipA stimulates the glycosyltransferase activity of PBP1A. The membrane-anchored cell division protein FtsN localises at preseptal sites and stimulates both activities of PBP1B. Genes zipA and ftsN can be individually deleted in ftsA* mutant cells, but the simultaneous depletion of both proteins is lethal and cells do not establish preseptal sites. Our data support a model according to which ZipA and FtsN-FtsA have semi-redundant roles in connecting the cytosolic FtsZ ring with the membrane-anchored peptidoglycan synthases during the preseptal phase of envelope growth.

Flotillin mediated membrane fluidity controls peptidoglycan synthesis and MreB movement

“…The increased fluidity at division sites is in line with a recent study that showed phases of different fluidity in Streptococcus pneumoniae membranes, with more fluid membranes and LipidII localizing at midcell 42 where the membrane is most bent. It may seem paradoxical that cells elongate when elongasome activity is reduced, but one has to remember that a large amount of the peptidoglycan synthesis contributing to elongation of bacterial cells is actually taking place at midcell, before the ingrowth of the septum 43-45 . The shift to peptidoglycan synthesis at future division sites makes the activity of PBP1 critical and explains why its deletion has such a dramatic effect in cells lacking flotillins.…”

pH-dependent activation of cytokinesis modulates Escherichia coli cell size

“…FtsN mutants defective for either domain fail to localize to the cytokinetic ring or to reduce size when overexpressed (Figs 4 and 5). Apart from promoting cytokinesis, FtsN also activates PBP1b [64,74,75], a nonessential cell wall synthesis enzyme speculated to play a role in cell wall repair during normal growth of the E. coli peptidoglycan sacculus [46,[76][77][78]. Midcell enrichment of FtsN in acidic media may also augment PBP1b activity at the septum and thus direct it to the region with the highest rates of peptidoglycan synthesis.…”

Real time monitoring of peptidoglycan synthesis by membrane-reconstituted penicillin binding proteins

“…A limitation of the recent kinetic study is that authors used assay conditions (e.g. very low enzyme concentration) at which PBP1B Ec is virtually inactive without an activator (Catherwood et al, 2020) as demonstrated previously (Pazos et al, 2018, Muller et al, 2007, thus the study likely substantially overestimated the extent of TPase activation by LpoB. P. aeruginosa uses a structurally different lipoprotein activator, LpoP, to stimulate its PBP1B (Greene et al, 2018).…”