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Figure 5
Comparison of Pizza6, PDB entry 2ymu and Tako8. Single blades of Pizza6 (PDB entry 3ww9; coloured blue), a highly symmetric naturally occurring seven-bladed propeller (PDB entry 2ymu, coloured magenta) and Tako8 (rainbow) were isolated (a) and superposed (b). The inner three strands of each blade superpose closely, while the turn between the first and the second strand and the region between the end of the fourth strand and the subsequent connecting loop deviate by up to 5 Å for Pizza6 and 3 Å for PDB entry 2ymu (b). Structure-based sequence alignments of a single Pizza blade versus Tako and of PDB entry 2ymu versus Tako are shown in (c), with the β-strands indicated as yellow arrows. The bar graphs indicate the Cα deviations after least-squares superposition of the two models, showing the larger differences at the C-­terminal end of the blade. The deviation between the first and second strands as well as the twist of the fourth strand is larger when the difference in number of repeats is larger. These differences influence the relative position of the blades around the central axis and help to control the number of blades in the complete propeller.

IUCrJ
Volume 6| Part 1| January 2019| Pages 46-55
ISSN: 2052-2525
https://doi.org/10.1107/S205225251801480X