Complete atomic model of the bacterial flagellar filament by electron cryomicroscopy

Koji Yonekura, Saori Maki-Yonekura, Keiichi Namba

Research output: Contribution to journalArticlepeer-review

566 Citations (Scopus)


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 Å resolution shows the feature of α-helical backbone and some large side chains. The atomic model built on the map reveals intricate molecular packing and an α-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.

Original languageEnglish
Pages (from-to)643-650
Number of pages8
Issue number6949
Publication statusPublished - 2003 Aug 7
Externally publishedYes

ASJC Scopus subject areas

  • General


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