Heterogeneity and multi-scale dynamics in the molecular bearing of the bacterial flagellum

Journal article

The bacterial flagellum is a protein-based rotary machine that drives bacterial motility. It comprises the bacterial flagellar motor (BFM), consisting of a stator which is anchored to the cell wall and a rotor in the cytoplasmic membrane, linked via the flagellar rod to the extracellular hook and filament. We observe passive rotational diffusion of six individual Escherichia coli flagella lacking torque-generating units via polarization microscopy of single gold nanorods attached to the hook, sampled at 250 kHz. Transitions across energy barriers of the 26-fold symmetric LP-ring/rod flagellar bearing exhibit highly non-Poissonian kinetics spanning four orders of magnitude in time scale. At sub-millisecond timescales we observe anomalous ultra-slow diffusion typically associated with disordered systems, despite the ordered crystalline atomic structure of the bearing revealed by cryo-Electron Microscopy. Over longer periods, we observe dynamic shifts in the preferred angular positions, indicating that the bearing's energy landscape evolves over time.

Authors: Rieu, M; Xu, D; Subramaniam, G; Nord, AL; Courbet, A

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Nature Research
• Journal: Nature Communications
• Publication date: 2026-06-12
• DOI: 10.1038/s41467-026-74079-9
• EISSN: 2041-1723
• ISSN: 2041-1723
• Language: English
• Keywords: Molecular machine; Cytoplasm; Extracellular; Rotational diffusion; Diffusion; Stator; Flagellum; Dynamics (music)