Relaxation of Loaded ESCRT-III Spiral Springs Drives Membrane Deformation.
Bottom Line: We reasoned that Snf7 spirals could function as spiral springs.Furthermore, we observed that the elastic expansion of compressed Snf7 spirals generated an area difference between the two sides of the membrane and thus curvature.This spring-like activity underlies the driving force by which ESCRT-III could mediate membrane deformation and fission.
Affiliation: University of Geneva, Department of Biochemistry, quai Ernest Ansermet 30, 1211 Geneva 4, Switzerland.Show MeSH
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Mentions: We first acquired images of Snf7 patches by AFM. GUVs composed of 60% DOPC and 40% DOPS were burst on a mica support (Figure S2A). After a four hours incubation of Snf7 at 1 μM, AFM images revealed that the micron-sized Snf7 patches consisted of packed arrays of Snf7 circular assemblies (Figure 2A; Figure S2B). Each assembly was formed by concentric circle-like structures. However, in these packed conditions, rather than being perfectly circular, each assembly was deformed into polygons with six neighbors on average (Figure 2B). The average external radius was 123 ± 35 nm (in the following, values are mean ± SD unless otherwise noted; n = 295) (Figure 2C), and the innermost circle had an average radius of 18 ± 3 nm (n = 120) (Figure 2D). The average distance between successive circles was nm (n = 80) (Figure 2E).
Affiliation: University of Geneva, Department of Biochemistry, quai Ernest Ansermet 30, 1211 Geneva 4, Switzerland.