Figure 1: Approximate resolution of different fluorescence microscopy methods using the example of a Gram-negative bacterial cell with a ribosome and a type 3 secretion system (T3SS). (A) Schematic true-scale representation of a Gram-negative rod-shaped bacterium (1 µm width, 2.5 µm length) carrying a T3SS (~40 nm width, ~150 nm length) and a ribosome (~20 nm diameter). The ellipsoids represent the approximate resolution inx , y and z for confocal microscopy, structured illumination microscopy (SIM), stimulated emission depletion (STED) nanoscopy, single molecule localization microscopy (SMLM) and minimal photon flux (MINFLUX) nanoscopy. Approximate resolution values in 2D (blue) and 3D (green) mode of the indicated microscopy methods are shown. The T3SS, its translocon and YscL complex and the 3D-MINFLUX ellipsoid are shown enlarged in the insets. IM, inner membrane; PG, peptidoglycan layer; OM, outer membrane; HCM, host cell membrane. (B) True-scale representation of various molecules used for fluorescent labelling of target structures in relation to the 3D-MINFLUX nanoscopy resolution. Structures were obtained from the Protein Data Bank (PDB): 1igt (IgG), 5dty (green fluorescent protein), 6i2g (NbALFA bound to ALFA-tag), 6y7a (Halo-tag) and 7k00 (bacterial ribosome).
Table 1: Selected super resolution microscopy studies in bacteria