title: Complete atomic model of the bacterial flagellar filament by electron cryomicroscopy.
abstract: The bacterial flagellar filament is a helical propeller for bacterial locomotion. It is a helical assembly of a single protein, flagellin, and its tubular structure is formed by 11 protofilaments in two distinct conformations, L- and R-type, for supercoiling. The X-ray crystal structure of a flagellin fragment lacking about 100 terminal residues revealed the protofilament structure, but the full filament structure is still essential for understanding the mechanism of supercoiling and polymerization. Here we report a complete atomic model of the R-type filament by electron cryomicroscopy. A density map obtained from image data up to 4 A resolution shows the feature of alpha-helical backbone and some large side chains. The atomic model built on the map reveals intricate molecular packing and an alpha-helical coiled coil formed by the terminal chains in the inner core of the filament, with its intersubunit hydrophobic interactions having an important role in stabilizing the filament.
authors.affiliation: Protonic NanoMachine Project, ERATO, JST.
authors.forename: Koji
authors.initials: K
authors.lastname: Yonekura
authors.forename: Saori
authors.initials: S
authors.lastname: Maki-Yonekura
authors.forename: Keiichi
authors.initials: K
authors.lastname: Namba
mesh_terms: D020285:Cryoelectron Microscopy; D018360:Crystallography, X-Ray; D005407:Flagella / Q000737:chemistry* / Q000648:ultrastructure*; D005408:Flagellin / Q000737:chemistry* / Q000235:genetics / Q000648:ultrastructure*; D057927:Hydrophobic and Hydrophilic Interactions; D008958:Models, Molecular; D020125:Mutation, Missense; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D021122:Protein Subunits; D012486:Salmonella typhimurium / Q000737:chemistry* / Q000235:genetics / Q000648:ultrastructure; D055672:Static Electricity
chemical_list: D021122:Protein Subunits; D005408:Flagellin