title: Identical folds used for distinct mechanical functions of the bacterial flagellar rod and hook.
abstract: The bacterial flagellum is a motile organelle driven by a rotary motor, and its axial portions function as a drive shaft (rod), a universal joint (hook) and a helical propeller (filament). The rod and hook are directly connected to each other, with their subunit proteins FlgG and FlgE having 39% sequence identity, but show distinct mechanical properties; the rod is straight and rigid as a drive shaft whereas the hook is flexible in bending as a universal joint. Here we report the structure of the rod and comparison with that of the hook. While these two structures have the same helical symmetry and repeat distance and nearly identical folds of corresponding domains, the domain orientations differ by ∼7°, resulting in tight and loose axial subunit packing in the rod and hook, respectively, conferring the rigidity on the rod and flexibility on the hook. This provides a good example of versatile use of a protein structure in biological organisms.
authors.affiliation: Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan.|Riken Quantitative Biology Center, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Fujii
authors.affiliation: Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Kato
authors.affiliation: Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Koichi D
authors.initials: KD
authors.lastname: Hiraoka
authors.affiliation: Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Miyata
authors.affiliation: Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Tohru
authors.initials: T
authors.lastname: Minamino
authors.affiliation: Department of Biology, University of Utah, Salt Lake City, Utah 84112, USA.
authors.forename: Fabienne F V
authors.initials: FF
authors.lastname: Chevance
authors.affiliation: Department of Biology, University of Utah, Salt Lake City, Utah 84112, USA.
authors.forename: Kelly T
authors.initials: KT
authors.lastname: Hughes
authors.affiliation: Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan.|Riken Quantitative Biology Center, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Keiichi
authors.identifier: 0000-0003-2911-5875
authors.initials: K
authors.lastname: Namba
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D020285:Cryoelectron Microscopy; D005407:Flagella / Q000502:physiology* / Q000648:ultrastructure; D021621:Imaging, Three-Dimensional; D062105:Molecular Docking Simulation; D020409:Molecular Motor Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D000072417:Protein Domains / Q000502:physiology; D017433:Protein Structure, Secondary / Q000502:physiology; D012486:Salmonella typhimurium / Q000166:cytology / Q000502:physiology*; D016415:Sequence Alignment
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; C097681:FlgE protein, Bacteria; D020409:Molecular Motor Proteins