Bacterial flagella construction and autotomy revealed by single-cell fluorescence imaging

Xiang-Yu Zhuang^1*, Chien-Jung Lo¹

¹Department of Physics and Graduate Institute of Biophysics, National Central University, Jhongli, Taiwan

* Presenter:Xiang-Yu Zhuang, email:xiangyu066@gmail.com

Bacterial flagella are thin helical hollow filaments which length are several micrometers long and only 20 nanometers wide. During flagellar growth, flagellin delivers to the distal end of the filament and folded into flagellum. However, whether flagellar motor is permanent and stable structures and, if not, the trigger condition and timing of their production and loss during the bacterial life cycle remain poorly understood.
　Many Vibrio species (e.g. Vibrio alginolyticus, Vibrio fischeri) have sheathed flagella which are covered by a layer membrane-like structure. Therefore, we develop a visualization method using lipophilic dye (FM4-64) fast labelling to monitor flagellum in real-time. Our measurements demonstrated that bacterial flagellar growth mechanism agrees with the injection-diffusion model. Besides, we surprisingly find that Vibrio alginolyticus actively abandon their single polar flagella at stationary phase. Combining our fluorescent labeling protocol, experimental results, the molecular dynamic simulation, and mutagenesis approach, our results will shed the light of understanding the dynamic behavior of bacterial flagella from self-assemble to autotomy.

Keywords: flagellation, injection-diffusion model, self-assembly, flagellar ejection, Vibrio alginolyticus