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A–D
Computationally assembled CrSAS‐6[6HR] single (A, C) or double ring in register (ribbon diagram shown in different shades for clarity) (B, D) fitted into the 3D maps of the 36% T. mirabilis class (A, B) and the 45% T. agilis class (C, D). Dashed box shows longitudinal section through hub element (left), double chevron viewing point of longitudinal external views (right). Extra unaccounted densities in single ring fitting are indicated by arrowheads (A, C). Note that each elongated hub density can accommodate two tightly stacked CrSAS‐6[6HR] rings (B, D), and that only one ring can fit into the thin hub element in the 45% T. agilis class (C, D). Indicated distances stem from measurements on the fitted models.
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E
Purified CrSAS‐6[NL] protein self‐organized into stacks and analyzed by cryo‐ET; one longitudinal view and one transverse view are highlighted by a dashed rectangle and a dashed circle, respectively.
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F, G
2D views through STA of in vitro self‐assembled CrSAS‐6[NL] proteins. Transverse sections at the indicated heights through one assembly unit (F), as well as longitudinal view (G) of the area delineated by a dashed box in (F); white arrowhead denotes position of line scan along the vertical axis at the level of the hub, with corresponding pixel intensities in arbitrary units (AU). The average distance between two hub elements is 4.5 ± 0.3 nm (N = 7; dashed lines).
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H
Longitudinal view of in vitro self‐assembled CrSAS‐6[NL] proteins STA 3D map. Note densities bridging successive hubs vertically (arrows).
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I
Two CrSAS‐6[HR] single rings fitted into the 3D map of in vitro self‐assembled CrSAS‐6[NL] proteins. Dashed box indicates longitudinal section through hub element (left), double chevron indicates viewing point of longitudinal external view (right). Note that the 3D map can accommodate rings stacked 4.4 nm apart (measured on fitted ring models) and that vertical densities linking hubs are partially occupied.
