Fig. 4: Impaired early coat assembly in the absence of SpoIIQ or CotE.

a–e Slices through cryo-electron tomograms of ΔspoIIQ or ΔcotE forespores, shown in full view (scale bars = 100 nm) or as magnified views of specific regions (scale bars = 50 nm). a The bead-like patterns (red and orange brackets) accumulate in ΔspoIIQ sporangia. b–c In the absence of CotE, the crenelated layer (cyan arrowhead), the light (cyan brackets) and dark (lime bracket) matrices and the dark smooth layer (green arrowhead) are visible but the bead-like patterns are absent. In addition, the dark smooth layer localizes right above the dark matrix (b), which abnormally extends toward the mother cell (c, lime arrowheads). d Analysis of the 3D organization of the coat layers by observing their aspect in planes orthogonal to the section. The blue inset boxes the analyzed region; the cyan lines indicate the orientation of the plane used to generate panels i–iii. e Slices through a cryo-electron tomogram of a ΔcotE forespore shown in full view and as magnified views with incremental depth (boxed in violet). A comb-like structure protrudes from the dark smooth layer in regions where it detaches from the dark matrix. The images are representative of 2 independent experiments, with 2 (a), 6 (b), 3 (c), 6 (d) and 1 (e) cells displaying similar features.