Peptidoglycan–outer membrane attachment generates periplasmic pressure to prevent lysis in Gram-negative bacteria

• Published in: Nature microbiology Vol. 10; no. 8; pp. 1963 - 1974
• Main Authors: Deghelt, Michaël, Cho, Seung-Hyun, Sun, Jiawei, Govers, Sander K., Janssens, Arne, Dachsbeck, Alix Vincent, Remaut, Han K., Huang, Kerwyn Casey, Collet, Jean-François
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.08.2025; Nature Publishing Group
• Subjects: 14/28; 14/35; 14/63; 631/326/1320; 631/326/41/88; 82/1; 82/62; Antibiotics; Bacteria; Bacterial Outer Membrane - metabolism; Bacterial Outer Membrane Proteins - genetics; Bacterial Outer Membrane Proteins - metabolism; Bacteriolysis; Biomedical and Life Sciences; Cell death; Cell Membrane - metabolism; Cell Wall - metabolism; Cell walls; Cells; Escherichia coli; Escherichia coli - genetics; Escherichia coli - metabolism; Escherichia coli - physiology; Escherichia coli Proteins - genetics; Escherichia coli Proteins - metabolism; Gram-negative bacteria; Gram-Negative Bacteria - metabolism; Infectious Diseases; Life Sciences; Lipoproteins; Lysis; Mathematical models; Medical Microbiology; Membranes; Microbiology; Microfluidics; Osmotic Pressure; Parasitology; Peptidoglycan - metabolism; Peptidoglycans; Periplasm; Periplasm - metabolism; Periplasm - physiology; Permeability; Turgor; Virology
• ISSN: 2058-5276; 2058-5276
• DOI: 10.1038/s41564-025-02058-9

Bacteria are subject to a substantial concentration differential of osmolytes between the interior and exterior of the cell, resulting in turgor pressure. Failure to mechanically balance this turgor pressure causes cells to burst. Here, using microfluidics, imaging, biochemistry and mathematical modelling, we analysed how Escherichia coli cells with structural mutations in the envelope respond to hypoosmotic shocks. We show that the peptidoglycan cell wall forms a mechanical unit with the outer membrane that limits periplasmic volume increase under hypoosmotic shock, allowing osmotic pressure build-up in the periplasm. In turn, this periplasmic pressure balances cytoplasmic turgor across the inner membrane, preventing cell lysis and death. Thus, while the peptidoglycan layer is necessary, it is not sufficient to maintain turgor and protect cells from lysis. We propose a model in which the entire cell envelope, including the periplasm, collectively enables Gram-negative bacteria to overcome osmotic challenges. Outer membrane attachment to peptidoglycan enables periplasmic pressure to build up and counter cytoplasmic turgor pressure, preventing lysis during osmotic challenges in Escherichia coli .