Year: 2026
Type: preprint
Abstract: Polymerization and disassembly govern the cellular functions of cytoskeletal proteins. Canonical nucleotide-dependent polymers, including actin and microtubules, renew their nucleotide state through subunit subunit dissociation, nucleotide exchange in solution and repolymerization. Yet the assembly dynamics of the membrane-bound bacterial actin MreB remain unresolved. Here, using total internal reflection fluorescence microscopy and high-speed atomic force microscopy, we visualise Bacillus subtilis MreB assembly on supported lipid bilayers in real time. ATP binding drives polymerization into symmetrically elongating filaments, whereas ATP hydrolysis within filaments promotes disassembly. Unexpectedly, nucleotides continuously exchange within membrane-bound filaments without detectable subunit turnover, coupling filament stability to the surrounding nucleotide pool: ATP exchange stabilizes filaments, whereas ADP exchange triggers rapid fragmentation and disassembly. Monte-Carlo modelling and single-cell in vivo imaging support this mechanism. Thus, intrafilament nucleotide exchange enables MreB filaments to renew their nucleotide state without polymer turnover, revealing nucleotide-state rejuvenation as a new mode of biological polymer regulation.
Institutions: AgroParisTech, Université Paris-Saclay, Microbiologie de l’alimentation au service de la santé, Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement, Kanazawa University, Nano Life Science Institute, Kanazawa University, Centre National de la Recherche Scientifique, Aix-Marseille Université, Institut de Biologie du Développement Marseille, Max Bergmann Center of Biomaterials, Leibniz Institute of Polymer Research, Université Paris Cité, Institut Jacques Monod, National University of Singapore, Mechanobiology Institute, Bridging Mechanobiology and Medicine
Language: English
Subfield: Cell Biology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W7171251092