Fig. 4: mGSDMA3^Nterm features high structural flexibility to assemble ring-shaped oligomers of different stoichiometries that show different stages of pore formation.

a High-resolution FD-based AFM topograph of mGSDMA3^Nterm oligomers inserted in SLMs made from E. coli polar lipid extract. Visible are individual mGSDMA3^Nterm assembling variably sized and shaped oligomers. b Left axis, occurrence of ring-shaped mGSDMA3^Nterm oligomers (n = 174) showing symmetries ranging from 18 to 36. The most prominent stoichiometry observed is 30, followed by 31, 28, 27, 26 and 29. Right axis, outer diameter of ring-shaped mGSDMA3^Nterm oligomers having different stoichiometries. c Distance between mGSDMA3^Nterm at the outer periphery of ring-shaped oligomers having different stoichiometries. Distances were estimated from the outer diameter of ring-shaped oligomers (b) divided by the number of mGSDMA3^Nterm. Data points (red) in (b, c) give averages and errors SE of 174 ring-shaped mGSDMA3^Nterm oligomers analyzed. Insets show a hypothetical packing of mGSDMA3^Nterm arranged into ring-shaped oligomers having 20 and 30 stoichiometries. d Correlation averaged AFM topographs. Top row, selected high-resolution contact mode and FD-based AFM topographs of individual ring-shaped mGSDMA3^Nterm oligomers inserted into SLMs and having different stoichiometries ranging from 22 to 30. Bottom row, symmetrized correlation averages of the exemplified AFM topographs showing stoichiometries ranging from 22 to 30 (Methods). e High-resolution contact mode and FD-based AFM topographs and height profiles of individual ring-shaped mGSDMA3^Nterm oligomers inserted in lipid membranes. Oligomers residing in the pre-pore and pore state protrude at same height above the lipid membrane (see Fig. 1). Red lines indicate height profiles, black dashed lines indicate the SLM surface (0 nm height). The full-range color scale of the topographs corresponds to a vertical scale of 8 nm (a) and 6 nm (d, e). Scale bars, 30 nm (a), 20 nm (d), and 10 nm (e).