
==== Front
bioRxiv
BIORXIV
bioRxiv
2692-8205
Cold Spring Harbor Laboratory

10.1101/2024.09.03.611099
preprint
1
Article
Non-linear stress-softening of the bacterial cell wall confers cell shape homeostasis
Bardetti Paola
Barber Felix
Rojas Enrique R. http://orcid.org/0000-0003-3388-2794

08 9 2024
2024.09.03.611099https://creativecommons.org/licenses/by-nc-nd/4.0/ This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which allows reusers to copy and distribute the material in any medium or format in unadapted form only, for noncommercial purposes only, and only so long as attribution is given to the creator.
http://biorxiv.org/lookup/doi/10.1101/2024.09.03.611099
nihpp-2024.09.03.611099.pdf
Abstract

The bacillus - or rod - is a pervasive cellular morphology among bacteria. Rod-shaped cells elongate without widening by reinforcing their cell wall anisotropically to prevent turgor pressure from inflating cell width. Here, we demonstrate that a constrictive force is also essential for avoiding pressure-driven widening in Gram-positive bacteria. Specifically, super-resolution measurements of the nonlinear mechanical properties of the cell wall revealed that across a range of turgor pressure cell elongation directly causes width constriction, similar to a “finger trap” toy. As predicted by theory, this property depends on cell-wall anisotropy and is precisely correlated with the cell’s ability to maintain a rod shape. Furthermore, the acute non-linearities in the dependence between cell length and width deformation result in a negative-feedback mechanism that confers cell-width homeostasis. That is, the Gram-positive cell wall is a “smart material” whose exotic mechanical properties are exquisitely adapted to execute cellular morphogenesis.
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pmc
