How to stay in one piece : outer membrane - peptidoglycan tethering in Enterobacteriaceae

Pierre Despas, Elisa
(2026)

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Authors
Supervisors
Collet, Jean-François  
 ;
Deghelt, Michaël  
Abstract
(en) The envelope of diderm bacteria is a complex structure essential for viability. Tight tethering of the outer membrane to the underlying peptidoglycan is a key determinant of envelope stability, osmoprotection, and resistance to environmental stress. Here, we show that in E. coli, outer membrane-peptidoglycan (OM-PG) tethering is functionally more intricate than previously appreciated. Although the three principal connectors - the linker Lpp and the non-covalent tethers OmpA and Pal - display partial functional redundancy, their contributions are not equivalent. We uncover an unrecognized role for Pal in resistance to hypoosmotic stress, independent of cell division, and identify a functional hierarchy among the Lpp-anchoring L,D-transpeptidases. Additionally, we characterize LppB, an Lpp homolog from S. Typhimurium which assemble with Lpp into heterotrimers that dimerize via the unique penultimate cysteine of LppB, modulating overall Lpp-PG crosslinking. Together, our findings support a model in which OM-PG tethering functions as a dynamic and tunable mechanical network that sustains periplasmic pressure while balancing envelope strength and flexibility.
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Pierre Despas, E. (2026). How to stay in one piece : outer membrane - peptidoglycan tethering in Enterobacteriaceae. https://hdl.handle.net/2078.5/277303