Giant flagellins form thick flagellar filaments in two species of marine γ-proteobacteria
Fig 2
The Oceanospiralles giant flagellin forms a thick filament and evolved via an internal duplication.
(A) TEM images of B. marisrubri and O. marinus. The images are typical of the cell morphology and flagellation pattern that we observed for each strain. (B) Negatively stained TEM images of representative flagellar filaments from B. marisrubri and O. marinus. A filament (24 nm diameter) from S. Typhimurium is also shown for comparison. All images are to the same scale. (C) Schematic depicting the phylogeny and occurrence of DE regions in related organisms. The phylogeny was determined using only the N- and C-terminal sequences that make up the D0 and D1 domains. Domain Extension (DE) regions are depicted in green; the C-terminal duplication is depicted in teal green. Arrows and accompanying grey boxes indicate inferred points at which the DE region was duplicated (“i”) and at which an additional insert was added between DE1 and DE2 (“ii”). Scale bar denotes average number of amino acid substitutions per site.