Figure 5: mDia1(FH1FH2) can generate piconewton pulling forces on depolymerizing actin filaments.
From: Formin mDia1 senses and generates mechanical forces on actin filaments
(a) Effect of force on the depolymerization rate of ADP-actin filaments bound to mDia1(FH1FH2) anchored by their FH2 domain, in the presence of 1 μM (red squares, n=4 filaments), 4 μM (green diamonds, n=8) and 10 μM (blue bullets, n=4) profilin. Open symbols correspond to control experiments with unanchored formins at the barbed end of filaments grown from anchored spectrin-actin seeds. Error bars are s.d.. Lines are fit of the data by equation (3). Inset: epifluorescence time sequence of an ADP-actin filament bound to a surface-anchored mDia1(FH1FH2), depolymerizing in the presence of 4 μM profilin, while exposed to a flow velocity of 52 μm s−1 (Supplementary Movie 2). Only the fluorescent segment near the pointed end is visible. The interval between images is 20 s. (b) Depolymerization rate of ADP-actin filament barbed ends by mDia1(FH1FH2) in the absence of force, as a function of profilin concentration (data points), compared with the depolymerization rate without mDia1 (dashed line, determined in Jegou et al.17).
