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Relaxation of Loaded ESCRT-III Spiral Springs Drives Membrane Deformation.

Chiaruttini N, Redondo-Morata L, Colom A, Humbert F, Lenz M, Scheuring S, Roux A - Cell (2015)

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.

View Article: PubMed Central - PubMed

Affiliation: University of Geneva, Department of Biochemistry, quai Ernest Ansermet 30, 1211 Geneva 4, Switzerland.

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Related in: MedlinePlus

Build-up of Lateral Compression in Snf7 Spirals by Polymerization(A) HS-AFM images of Snf7 spirals acquiring polygonal shapes with time.(B) AFM Topography and nanomechanical mapping of polygonal Snf7 spirals. A significant proportion of spirals (dashed outlines) have a lower center with increased mechanical stiffness.(C) Snf7 polymerization on GUVs made of DOPC 60% / DOPS 40% + Rhodamine-PE 0.1% (red), 0.003% DOPE-Peg2000-Biotin. GUVs are incubated with 500 nM Snf7-Alexa488 (green). Top: SDC images of a GUV equatorial plane during Snf7 polymerization. Bottom: fluorescence intensity (equatorial plane) of 4 GUVs with time.(D) GUVs before (top) and after (bottom) several hours of incubation with Snf7-Alexa488.(E) Snf7 coated GUVs keep the aspirated shape after release from the micropipette.(F) Sketch of membrane stretching by Snf7 spiral compression.(G) Schematic of the membrane tension measurement setup combining holding pipette, injection pipette, bead within an optical trap, giant vesicle (red) and Snf7 (green).(H) Top image: SDC image of a membrane tension measurement experiment (red = membrane, green = Snf7-Alexa488). Note that Snf7-Alexa488 did not polymerize on the membrane nanotube. Bottom: brightfield image of the same vesicle. The yellow cross indicates the resting position of the bead held by the optical trap.(I) Top: Normalized Snf7 fluorescence intensity versus time (measured from equatorial plane); bottom: force exerted by the membrane nanotube on the bead versus time. See also Figure S5.
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fig5: Build-up of Lateral Compression in Snf7 Spirals by Polymerization(A) HS-AFM images of Snf7 spirals acquiring polygonal shapes with time.(B) AFM Topography and nanomechanical mapping of polygonal Snf7 spirals. A significant proportion of spirals (dashed outlines) have a lower center with increased mechanical stiffness.(C) Snf7 polymerization on GUVs made of DOPC 60% / DOPS 40% + Rhodamine-PE 0.1% (red), 0.003% DOPE-Peg2000-Biotin. GUVs are incubated with 500 nM Snf7-Alexa488 (green). Top: SDC images of a GUV equatorial plane during Snf7 polymerization. Bottom: fluorescence intensity (equatorial plane) of 4 GUVs with time.(D) GUVs before (top) and after (bottom) several hours of incubation with Snf7-Alexa488.(E) Snf7 coated GUVs keep the aspirated shape after release from the micropipette.(F) Sketch of membrane stretching by Snf7 spiral compression.(G) Schematic of the membrane tension measurement setup combining holding pipette, injection pipette, bead within an optical trap, giant vesicle (red) and Snf7 (green).(H) Top image: SDC image of a membrane tension measurement experiment (red = membrane, green = Snf7-Alexa488). Note that Snf7-Alexa488 did not polymerize on the membrane nanotube. Bottom: brightfield image of the same vesicle. The yellow cross indicates the resting position of the bead held by the optical trap.(I) Top: Normalized Snf7 fluorescence intensity versus time (measured from equatorial plane); bottom: force exerted by the membrane nanotube on the bead versus time. See also Figure S5.

Mentions: AFM images of packed arrays of spirals showed that filaments at the contact zone between spirals were flattened, resulting in spirals acquiring a polygonal shape that was more pronounced for longer incubation times (Figure 5A). Moreover, the central area of some of these polygons was pushed toward the substrate, as seen in the height profile of AFM images (Figure 5B). Also, the centers of these spirals were often found to be stiffer as seen in AFM mechanical maps (Figure 5B). We reasoned that this deformation reflected lateral compression of the spirals as the membrane became covered with Snf7. To study the correlation between polymerization rate and lateral compression of the Snf7 assemblies, we ought to measure them simultaneously.


Relaxation of Loaded ESCRT-III Spiral Springs Drives Membrane Deformation.

Chiaruttini N, Redondo-Morata L, Colom A, Humbert F, Lenz M, Scheuring S, Roux A - Cell (2015)

Build-up of Lateral Compression in Snf7 Spirals by Polymerization(A) HS-AFM images of Snf7 spirals acquiring polygonal shapes with time.(B) AFM Topography and nanomechanical mapping of polygonal Snf7 spirals. A significant proportion of spirals (dashed outlines) have a lower center with increased mechanical stiffness.(C) Snf7 polymerization on GUVs made of DOPC 60% / DOPS 40% + Rhodamine-PE 0.1% (red), 0.003% DOPE-Peg2000-Biotin. GUVs are incubated with 500 nM Snf7-Alexa488 (green). Top: SDC images of a GUV equatorial plane during Snf7 polymerization. Bottom: fluorescence intensity (equatorial plane) of 4 GUVs with time.(D) GUVs before (top) and after (bottom) several hours of incubation with Snf7-Alexa488.(E) Snf7 coated GUVs keep the aspirated shape after release from the micropipette.(F) Sketch of membrane stretching by Snf7 spiral compression.(G) Schematic of the membrane tension measurement setup combining holding pipette, injection pipette, bead within an optical trap, giant vesicle (red) and Snf7 (green).(H) Top image: SDC image of a membrane tension measurement experiment (red = membrane, green = Snf7-Alexa488). Note that Snf7-Alexa488 did not polymerize on the membrane nanotube. Bottom: brightfield image of the same vesicle. The yellow cross indicates the resting position of the bead held by the optical trap.(I) Top: Normalized Snf7 fluorescence intensity versus time (measured from equatorial plane); bottom: force exerted by the membrane nanotube on the bead versus time. See also Figure S5.
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fig5: Build-up of Lateral Compression in Snf7 Spirals by Polymerization(A) HS-AFM images of Snf7 spirals acquiring polygonal shapes with time.(B) AFM Topography and nanomechanical mapping of polygonal Snf7 spirals. A significant proportion of spirals (dashed outlines) have a lower center with increased mechanical stiffness.(C) Snf7 polymerization on GUVs made of DOPC 60% / DOPS 40% + Rhodamine-PE 0.1% (red), 0.003% DOPE-Peg2000-Biotin. GUVs are incubated with 500 nM Snf7-Alexa488 (green). Top: SDC images of a GUV equatorial plane during Snf7 polymerization. Bottom: fluorescence intensity (equatorial plane) of 4 GUVs with time.(D) GUVs before (top) and after (bottom) several hours of incubation with Snf7-Alexa488.(E) Snf7 coated GUVs keep the aspirated shape after release from the micropipette.(F) Sketch of membrane stretching by Snf7 spiral compression.(G) Schematic of the membrane tension measurement setup combining holding pipette, injection pipette, bead within an optical trap, giant vesicle (red) and Snf7 (green).(H) Top image: SDC image of a membrane tension measurement experiment (red = membrane, green = Snf7-Alexa488). Note that Snf7-Alexa488 did not polymerize on the membrane nanotube. Bottom: brightfield image of the same vesicle. The yellow cross indicates the resting position of the bead held by the optical trap.(I) Top: Normalized Snf7 fluorescence intensity versus time (measured from equatorial plane); bottom: force exerted by the membrane nanotube on the bead versus time. See also Figure S5.
Mentions: AFM images of packed arrays of spirals showed that filaments at the contact zone between spirals were flattened, resulting in spirals acquiring a polygonal shape that was more pronounced for longer incubation times (Figure 5A). Moreover, the central area of some of these polygons was pushed toward the substrate, as seen in the height profile of AFM images (Figure 5B). Also, the centers of these spirals were often found to be stiffer as seen in AFM mechanical maps (Figure 5B). We reasoned that this deformation reflected lateral compression of the spirals as the membrane became covered with Snf7. To study the correlation between polymerization rate and lateral compression of the Snf7 assemblies, we ought to measure them simultaneously.

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.

View Article: PubMed Central - PubMed

Affiliation: University of Geneva, Department of Biochemistry, quai Ernest Ansermet 30, 1211 Geneva 4, Switzerland.

Show MeSH
Related in: MedlinePlus