Graduate School of Frontier Biosciences, Osaka University

Japanese

Insight into structural remodeling of the FlhA ring responsible for bacterial flagellar type III protein export

Journal Sci Adv 4 (2018)
Authors Naoya Terahara (1), Yumi Inoue (1), Noriyuki Kodera (2), Yusuke V. Morimoto (1, 3, 4), Takayuki Uchihashi (2, 5, 6), Katsumi Imada (7), Toshio Ando (2, 8), Keiichi Namba (1, 3), Tohru Minamino (1)
  1. Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan.
  2. Bio-AFM Frontier Research Center, Kanazawa University, Kanazawa 920-1192, Japan.
  3. RIKEN Quantitative Biology Center, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan.
  4. Department of Bioscience and Bioinformatics, Faculty of Computer Science and Systems Engineering, Kyushu Institute of Technology, 680-4 Kawazu, Iizuka, Fukuoka 820-8502, Japan.
  5. Department of Physics, Kanazawa University, Kanazawa 920-1192, Japan.
  6. Department of Physics, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan.
  7. Department of Macromolecular Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan.
  8. Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Goban-cho, Chiyoda-ku, Tokyo 102-0076, Japan.
Title Insight into structural remodeling of the FlhA ring responsible for bacterial flagellar type III protein export
Laboratory Protonic NanoMachine Group 〈Prof. Namba〉
Description The bacterial flagellum is a supramolecular motility machine. Flagellar assembly begins with the basal body, followed by the hook and finally the filament. A carboxyl-terminal cytoplasmic domain of FlhA (FlhAC) forms a nonameric ring structure in the flagellar type III protein export apparatus and coordinates flagellar protein export with assembly. However, the mechanism of this process remains unknown. We report that a flexible linker of FlhAC (FlhAL) is required not only for FlhAC ring formation but also for substrate specificity switching of the protein export apparatus from the hook protein to the filament protein upon completion of the hook structure. FlhAL was required for cooperative ring formation of FlhAC. Alanine substitutions of residues involved in FlhAC ring formation interfered with the substrate specificity switching, thereby inhibiting filament assembly at the hook tip. These observations lead us to propose a mechanistic model for export switching involving structural remodeling of FlhAC.