Open AccessStructure of the native supercoiled flagellar hook as a universal joint
Author(s) -
Takayuki Kato,
Fumiaki Makino,
Tomoko Miyata,
Péter Horváth,
Keiichi Namba
Publication year - 2019
Publication title -
nature communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.559
H-Index - 365
ISSN - 2041-1723
DOI - 10.1038/s41467-019-13252-9
Subject(s) - hook , protein filament , flagellum , twist , basal body , universal joint , dna supercoil , crystallography , physics , chemistry , geometry , structural engineering , dna , gene , biochemistry , mathematics , dna replication , engineering , thermodynamics
The Bacterial flagellar hook is a short supercoiled tubular structure made from a helical assembly of the hook protein FlgE. The hook acts as a universal joint that connects the flagellar basal body and filament, and smoothly transmits torque generated by the rotary motor to the helical filament propeller. In peritrichously flagellated bacteria, the hook allows the filaments to form a bundle behind the cell for swimming, and for the bundle to fall apart for tumbling. Here we report a native supercoiled hook structure at 3.6 Å resolution by cryoEM single particle image analysis of the polyhook. The atomic model built into the three-dimensional (3D) density map reveals the changes in subunit conformation and intersubunit interactions that occur upon compression and extension of the 11 protofilaments during their smoke ring-like rotation. These observations reveal how the hook functions as a dynamic molecular universal joint with high bending flexibility and twisting rigidity.