Escherichia coli bacteria can remodel their outer membrane permeability barrier independently of cellular growth, according to research published in Nature Communications. Researchers found that as bacterial elongation slows and cells enter stationary phase, the insertion of new lipopolysaccharide (LPS) continues while pre-existing LPS is preferentially shed through outer membrane vesicles.
Existing models attributed LPS turnover strictly to passive dilution during cell elongation and division, which limited how bacteria could adapt their surface barrier once growth slowed. The new findings demonstrate that vesicle release uncouples outer membrane turnover from active division, allowing ongoing surface remodeling in non-dividing states.
Researchers used pulse-chase metabolic labelling and super-resolution microscopy techniques, including dSTORM and 3D-SIM2, to track the molecules on the cell surface. Newly inserted LPS localized to discrete sites and remained segregated from older LPS rather than mixing freely across the outer leaflet. Spatiotemporal analysis confirmed an insertion-trapping model, showing that localized insertion combined with restricted lateral diffusion maintains distinct LPS patches without coarsening into larger domains.
The study was authored by Joe Nabarro, Natasha E. Hatton, Bartosz L. Kowalski, Christopher D. Spicer, Martin A. Fascione, Christoph G. Baumann, and Dmitri O. Pushkin across the departments of chemistry, biology, and mathematics at the University of York. Funding was provided by the University of York, the Biotechnology and Biological Sciences Research Council, a Horizon Europe Guarantee Award funded by UK Research and Innovation, and the Wellcome Trust.
