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This study demonstrates that the bacterial protein MreB, while not essential for survival in Pseudomonas aeruginosa, is critical for maintaining the rod-like cell shape and proper motility. Deletion of the mreB gene produces viable but spherical bacteria that lose all forms of movement, become more sensitive to certain antibiotics, and show altered biofilm formation patterns. The researchers also found that the downstream genes mreCD are essential for viability, and that spherical mutants are outcompeted by normal rod-shaped cells in mixed biofilms.
Why it matters
These findings have important implications for developing new antimicrobial strategies, as the MreB complex has been considered as a potential drug target. Understanding how P. aeruginosa adapts to loss of MreB function and the resulting trade-offs in fitness helps explain bacterial evolution and could inform more effective therapeutic approaches against this opportunistic pathogen.
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⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
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.{Delta} mreB mutants also display increased sensitivity to {beta}-lactam antibiotics and enhanced initial surface attachment, yet form more compact biofilms with reduced dispersal. In mixed-culture biofilms, spherical{Delta} mreB 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.