Supplementary Figure 2: In situ visualization of active type 3 secretion systems by cryo-electron tomography.
From: Structure of a pathogenic type 3 secretion system in action
(a) Reconstituted tomogram of Salmonella typhimurium cells containing T3SSs: SB905 cells containing wild type T3SSs (“Substrate-free”, WT) (left panel), and SB905 cells expressing SptP3-GFP (“Substrate-trapped”, +pSptP3-GFP) (right panel). Nine slices of the tomogram covering 179 Å were averaged (n = 9) (cy. = cytoplasm, ex. = extracellular space; bar = 100 nm). Dimensions of bases of injectisomes in situ or after purification are similar between each other and during substrate transport. (b) Upper panel: individual slices through a zoomed-in view of the tomogram containing membrane embedded, substrate-free T3SSs. T3SSs are displayed from left to right (bar = 50 nm), traversing through z-axis from top to bottom (voxel size 19.88 Å) Lower panel: individual slices through a zoomed-in view of the tomogram containing membrane embedded, substrate-trapped T3SSs. T3SSs are displayed from left to right (bar = 50 nm), traversing through z-axis from top to bottom (voxel size 19.88 Å).
