MreC and MreD balance the interaction between the elongasome proteins PBP2 and RodA

Abstract

Rod-shape of most bacteria is maintained by the elongasome, which mediates the synthesis and insertion of peptidoglycan into the cylindrical part of the cell wall. The elongasome contains several essential proteins, such as RodA, PBP2, and the MreBCD proteins, but how its activities are regulated remains poorly understood. Using E. coli as a model system, we investigated the interactions between core elongasome proteins in vivo. Our results show that PBP2 and RodA form a complex mediated by their transmembrane and periplasmic parts and independent of their catalytic activity. MreC and MreD also interact directly with PBP2. MreC elicits a change in the interaction between PBP2 and RodA, which is suppressed by MreD. The cytoplasmic domain of PBP2 is required for this suppression. We hypothesize that the in vivo measured PBP2-RodA interaction change induced by MreC corresponds to the conformational change in PBP2 as observed in the MreC-PBP2 crystal structure, which was suggested to be the “on state” of PBP2. Our results indicate that the balance between MreC and MreD determines the activity of PBP2, which could open new strategies for antibiotic drug development.

PGFinder, a novel analysis pipeline for the consistent, reproducible, and high-resolution structural analysis of bacterial peptidoglycans

“…Although the biological relevance of this property remains to be established, we cannot exclude the possibility that PG deacetylation in E. coli may contribute to PG homeostasis. Another striking outcome resulting from our automated search is the identification of a slightly higher amount of muropeptides containing anhydromuramic acid (4.55%) as compared to 2–3% ( Glauner et al, 1988 ; Liu et al, 2020 ). To explain the discrepancy between our work and data from the literature, it is tempting to assume that most of the muropeptides containing anhydromuramic acid identified with PGFinder were simply not searched in previous studies.…”

Genetic analysis of the septal peptidoglycan synthase FtsWI complex supports a conserved activation mechanism for SEDS-bPBP complexes

“…This proposed activation pathway is strikingly similar to that of the analogous RodA-PBP2 complex despite the regulatory proteins being completely unrelated. In this complex MreC interacts with the pedestal domain of PBP2 and is proposed to switch the complex to the active conformation [15,16,38,39]. However, a detailed mechanism by which these SEDS-bPBPs are stimulated by their activators is still not clear.…”

Midcell localization of PBP4 ofEscherichia colimodulates the timing of divisome assembly

“…Lipid II is used by glycosyltransferases (GTases), which polymerize the glycan chains, and TPase, which crosslink the stem peptides. The main PG synthases in E. coli are the class A PBPs (PBP1A and PBP1B) with GTase and TPase activities [4][5][6][7][8], the integral membrane proteins RodA and FtsW with GTase activity [9][10][11] and their partner TPases PBP2 and PBP3, respectively [12][13][14][15].…”