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

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

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

Navarro PP, Vettiger A, Hajdu R, Ananda VY, López-Tavares A, Schmid EW, Walter JC, Loose M, Chao LH, Bernhardt TG. 2026. The penicillin-binding protein PBP1b fortifies the Escherichia coli division site against osmotic rupture. Nature Microbiology.

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https://doi.org/10.1038/s41564-026-02403-6 [Published Version]

DOI

10.1038/s41564-026-02403-6

Journal Article | Epub ahead of print | English

Scopus indexed

Author

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

Department

Loose Group
Graduate School

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.

Publishing Year

2026

Date Published

2026-07-03

Journal Title

Nature Microbiology

Publisher

Springer Nature

Acknowledgement

We thank all members of the Bernhardt, Rudner, Navarro and Vettiger Laboratories for support and helpful conversations. We thank C. Genoud, J. Daraspe, A. Mucciolo and D. de Bellis at the Electron Microscopy Facility of the University of Lausanne and E. Jeanvoine for providing access to workstations for cryo-ET image processing; S. Sterling, C. Borsa, J. Podgorski, P. Vinh Dip, E. Brignole and A. Osherov at the MIT.nano cryo-EM facility, K. Song and C. Xu at the University of Massachusetts cryo-EM facility, and R. Walsh and Z. Li at the cryo-EM at Harvard Medical School facility for providing access to the cryo-EM microscopes and for all their help, advice and maintenance of cryo-EM equipment. AFM was performed at the Harvard University Center for Nanoscale Systems (CNS), a member of the National Nanotechnology Coordinated Infrastructure Network (NNCI), which is supported by the National Science Foundation under NSF award no. ECCS-2025158. We thank N. S. Colella for excellent advice on AFM data acquisition and analysis; the MicRoN imaging core at Harvard Medical School for excellent advice on live cell imaging and maintenance of fluorescence microscopes; B. Krautz for creating the cartoon illustrations (www.sciencecommunicated.com); and L. Miles and R. Aeschimann for assistance with strain construction. A.V. was supported by an EMBO long-term postdoctoral fellowship ALTF_89-2019, the Swiss National Science Foundation (SNSF) Postdoc.Mobility fellowship P500PB_203143. P.P.N. was a recipient of early postdoc.mobility and postdoc.mobility fellowships (P2BSP3_188112 and P400PB_199252). This work was also supported by funding from the National Institutes of Health (R35GM142553 to L.H.C. and R01AI083365 to T.G.B.), investigator funds from the Howard Hughes Medical Institute (T.G.B.), an SNSF project grant (320030-236243 to A.V.), an SNSF Starting Grant (TMSGI3_218251 to P.P.N.), an SNSF Project grant (320030-236069 to P.P.N), an SNSF SPARK grant (CRSK-3_237167 to P.P.N.), cryo-EM funds from the Faculty of Biology and Medicine at University of Lausanne to P.P.N. and the Foundation Pierre Mercier pour la Science (to P.P.N.).

eISSN

2058-5276

IST-REx-ID

22269

Cite this

Navarro PP, Vettiger A, Hajdu R, et al. The penicillin-binding protein PBP1b fortifies the Escherichia coli division site against osmotic rupture. Nature Microbiology. 2026. doi:10.1038/s41564-026-02403-6

Navarro, P. P., Vettiger, A., Hajdu, R., Ananda, V. Y., López-Tavares, A., Schmid, E. W., … Bernhardt, T. G. (2026). The penicillin-binding protein PBP1b fortifies the Escherichia coli division site against osmotic rupture. Nature Microbiology. Springer Nature. https://doi.org/10.1038/s41564-026-02403-6

Navarro, Paula P., Andrea Vettiger, Roman Hajdu, Virly Y. Ananda, Alejandro López-Tavares, Ernst W. Schmid, Johannes C. Walter, Martin Loose, Luke H. Chao, and Thomas G. Bernhardt. “The Penicillin-Binding Protein PBP1b Fortifies the Escherichia Coli Division Site against Osmotic Rupture.” Nature Microbiology. Springer Nature, 2026. https://doi.org/10.1038/s41564-026-02403-6.

P. P. Navarro et al., “The penicillin-binding protein PBP1b fortifies the Escherichia coli division site against osmotic rupture,” Nature Microbiology. Springer Nature, 2026.

Navarro, Paula P., et al. “The Penicillin-Binding Protein PBP1b Fortifies the Escherichia Coli Division Site against Osmotic Rupture.” Nature Microbiology, Springer Nature, 2026, doi:10.1038/s41564-026-02403-6.

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