MreB is dispensable for viability but critical for rod shape, motility and biofilm fitness in Pseudomonas aeruginosa
Abstract
Despite growing interest in the MreBCD morphogenetic complex as a potential antimicrobial target, its function in Pseudomonas aeruginosa remains poorly understood. While previous studies using the MreB inhibitor A22 have established its role in cell shape maintenance and pilus regulation, the impact of mreB deletion has not been comprehensively investigated. Using genetic and microscopy-based approaches, we show that deletion of mreB is viable in P. aeruginosa, but results in spherical cells that lose all forms of motility despite retaining flagella. Importantly, we uncover a previously overlooked polar effect of the in-frame mreB deletion on the downstream mreCD genes and show, using CRISPRi-mediated silencing, that mreCD expression is essential for viability. ΔmreB mutants also display increased sensitivity to β-lactam antibiotics and enhanced initial surface attachment, yet form more compact biofilms with reduced dispersal. In mixed-culture biofilms, spherical ΔmreB cells are outcompeted by rod-shaped wild-type cells and remain confined to the biofilm base. The identification of natural P. aeruginosa isolates carrying truncated mreB alleles further indicates that loss of MreB function can be tolerated in natural populations. Together, our findings reveal important contributions of the MreBCD system to viability, morphogenesis, motility and biofilm development in P. aeruginosa , providing new insights into bacterial adaptation and informing the development of targeted antimicrobial strategies.
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BibTeX
@misc{tunc2026mreb,
title = {{MreB is dispensable for viability but critical for rod shape, motility and biofilm fitness in Pseudomonas aeruginosa}},
author = {Merve Nur Tunç and Matteo Gérard and Aurélien Barbotin and Marie-Françoise Noirot-Gros and Marina Grégoire and Pierre-Emmanuel Douarre and Arnaud Bridier and Marie Delaby and Yves Brun and Steven Porter and Romain Briandet and Rut Carballido-López},
howpublished = {BioRxiv},
year = {2026},
month = aug,
doi = {10.64898/2026.08.02.742333},
url = {https://hal.science/hal-05749901v1},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - MreB is dispensable for viability but critical for rod shape, motility and biofilm fitness in Pseudomonas aeruginosa
AU - Merve Nur Tunç
AU - Matteo Gérard
AU - Aurélien Barbotin
AU - Marie-Françoise Noirot-Gros
AU - Marina Grégoire
AU - Pierre-Emmanuel Douarre
AU - Arnaud Bridier
AU - Marie Delaby
AU - Yves Brun
AU - Steven Porter
AU - Romain Briandet
AU - Rut Carballido-López
PY - 2026
DA - 2026/08/02
PB - BioRxiv
DO - 10.64898/2026.08.02.742333
UR - https://hal.science/hal-05749901v1
AB - Despite growing interest in the MreBCD morphogenetic complex as a potential antimicrobial target, its function in Pseudomonas aeruginosa remains poorly understood. While previous studies using the MreB inhibitor A22 have established its role in cell shape maintenance and pilus regulation, the impact of mreB deletion has not been comprehensively investigated. Using genetic and microscopy-based approaches, we show that deletion of mreB is viable in P. aeruginosa, but results in spherical cells that lose all forms of motility despite retaining flagella. Importantly, we uncover a previously overlooked polar effect of the in-frame mreB deletion on the downstream mreCD genes and show, using CRISPRi-mediated silencing, that mreCD expression is essential for viability. ΔmreB mutants also display increased sensitivity to β-lactam antibiotics and enhanced initial surface attachment, yet form more compact biofilms with reduced dispersal. In mixed-culture biofilms, spherical ΔmreB cells are outcompeted by rod-shaped wild-type cells and remain confined to the biofilm base. The identification of natural P. aeruginosa isolates carrying truncated mreB alleles further indicates that loss of MreB function can be tolerated in natural populations. Together, our findings reveal important contributions of the MreBCD system to viability, morphogenesis, motility and biofilm development in P. aeruginosa , providing new insights into bacterial adaptation and informing the development of targeted antimicrobial strategies.
SN - 2692-8205
ER -