Supplementary Figure 5: Single-particle analysis of substrate-free and substrate-trapped needle complexes.
From: Structure of a pathogenic type 3 secretion system in action
(a) Difference volume from substrate-trapped and substrate free needle complexes reconstructed without applying symmetry (C1). Surface views of half-sectioned and 15 degrees tilted three-dimensional volume of substrate-free (gray) and difference volume of substrate-trapped (blue) needle complexes reconstructed without applying symmetry (C1). (Difference corresponding to presence of substrate (Δsub); difference observed at the larger, inner ring-1, (ΔIR1)). Note, that the length of the extracellular needle filament is approximately 500 Å, however, due to a smaller boxsize and additional masking used during image data processing and reconstruction, the displayed needle filament is truncated. For comparison, entire isolated needle complexes are shown in Fig. 2b. (b) Resolution assessment by Fourier Shell Correlation. Upper panel: The resolution of substrate-free and substrate-trapped needle complexes reconstituted without symmetry (C1) corresponds to approximately 12 Angstroem (FSC=0.5). Lower panel: The resolution of substrate-free and substrate-trapped needle complexes reconstituted without symmetry (C1) and subsequently three-fold symmetrized (C3) corresponded to approximately 10 Angstroem measured at 0.5 FSC.
