Microtubules in Bacteria: Ancient Tubulins Build a Five-Protofilament Homolog of the Eukaryotic Cytoskeleton
(A) 2-D schematic of the proposed architecture of bacterial microtubules built from BtubA (dark-blue) and BtubB (light-blue). Protofilaments are numbered 1–5. (B) 3-D comparison of the architectures of a bacterial microtubule (left; BtubA in dark-blue; BtubB in light-blue) and a 13-protofilament eukaryotic microtubule (right; β-tubulin in black; α-tubulin in white). Seams and start-helices are indicated as in (A).