Fig. 1.

Cryo-EM and 3D reconstruction of Iho670 filaments. (A) Images of frozen hydrated Iho670 filaments. The arrow points to a bulbous structure sometimes seen at one end of the filaments, likely the basal body (60). The yellow line is an arc with a radius of curvature of 1,500 Å. (Scale bar: 500 Å.) (B) A cutaway view of the 3D reconstruction, with a ribbon representation of the atomic model shown in a different color for each subunit. The core of the filament is entirely α-helical, with each subunit contributing a single highly hydrophobic helix. (Scale bar: 50 Å.) (C) A single subunit from the model. The gray density shown is the region where we were unable to build a unique model, accounting for residues 135–195.