The penicillin-binding protein PBP1b fortifies the Escherichia coli division site against osmotic rupture.

Authors

Paula P Navarro, Andrea Vettiger, Roman Hajdu, Virly Y Ananda, Alejandro López-Tavares, Ernst W Schmid, Johannes C Walter, Martin Loose, Luke H Chao, Thomas G Bernhardt

Published in

Nature microbiology. Jul 03, 2026. Epub Jul 03, 2026.

Abstract

The divisome apparatus synthesizes septal peptidoglycan (PG) during bacterial division. In Escherichia coli, the class A penicillin-binding protein (aPBP) called PBP1b has been implicated in division, but its role in the process has remained unclear. Here we show using in situ cryo-electron tomography, genetics and other imaging methods that PBP1b is required to produce a wedge-like density of PG at the division site and that loss of this structure weakens the division site, making it hypersusceptible to osmotic lysis. Surprisingly, the activator LpoB needed for general PBP1b function was not required for its role in division. Of the two PBP1b isoforms produced in cells, we show that the one with an extended cytoplasmic N terminus localizes to and functions at the division site, probably via recruitment by the FtsA component of the divisome. The conservation of aPBPs with extended cytoplasmic N termini suggests that other Gram-negative bacteria may use similar mechanisms for division site reinforcement.

PMID:
42399561
Bibliographic data and abstract were imported from PubMed on 04 Jul 2026.

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