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. 2020 Mar 2;11:1153. doi: 10.1038/s41467-020-14894-w

Fig. 5. Cyt1Aa forms oligomers that fully perforate and eventually disrupt lipid bilayers.

Fig. 5

a Single cation-channel formation was not observed in black lipid membrane (BLM) experiments. b, c Cyt1Aa allows entry in both Sf21 (b) and NIH 3T3 cells (c) of co-incubated FITC-labelled (fluorescein isothiocyanate) dextran beads up to 8.5 nm in size. Scale bars = 10 µm. d–f Membrane-bound Cyt1Aa monomers exhibit mobility (d, e) and display the capacity to merge into larger membrane-bound aggregates (MBA). Scale bars = 3 µm (d) and 300 nm (e, f). g A significant positive correlation was observed between the surface of MBA and the time elapsed since toxin addition. h 35 min after toxin addition, membrane perforation is observed at the periphery of MBA. Scale bar = 500 nm. i The depth of holes can reach 4.5 nm, consistent with a full spanning of the lipid bilayer. j, k A significant negative correlation is observed between the surface of holes and their depth (j), but not between the latter and the combined area of the hole and the parent MBA (k). l, m Formation of MBA and holes was neither observed for the activated form of the non-toxic Q168E mutant (l) nor for the BSA control (m). Scale bars = 500 nm. n–q Transmission electron microscopy captures liposome lysis by the toxin (n), and the resulting release of arciform oligomers (o–q). Scale bars = 50 nm (n, q), 20 nm (p) and 100 nm (o). Source data are provided as a Source Data file.