Panel A and Panel B are line graphs showing the fraction of surviving branches over time under different buffer conditions. Panel A shows data for 0.8 millimolar BeFx buffer and regular buffer, with an average force of 3.2 plus or minus 0.3 piconewtons. Panel B shows data for 2 millimolar BeFx buffer and regular buffer, with an average force of 1.9 plus or minus 0.2 piconewtons. Both graphs have time in seconds on the x-axis and the fraction of surviving branches on the y-axis. Panel C is a scatter plot showing the debranching rate as a function of force for ADP mother filament and ADP-BeFx mother filament. The x-axis represents force in piconewtons, and the y-axis represents the debranching rate in reciprocal seconds. The plot includes error bars representing 95 percent confidence intervals and lines representing single exponential fits from each population of debranching rates.
Nucleotide state of the mother filament does not affect debranching rate. (A and B) Branches initiated as detailed in Fig. 1 A are exposed to a solution containing either 0.8 (A) or 2 (B) mM BeFx for 4 min. Debranching events are recorded first in the same 0.8 or 2 mM BeFx buffer, before switching to a regular buffer solution. All buffer conditions contain 0.1 µM Alexa Fluor 568 (10%)–G-ATP-actin. For each condition, 100 branches were analyzed. Image acquisition rate is 1 frame every 5 s. (C) ADP-Arp2/3 complex branches initiated either from ADP- or ADP-BeFx-actin mother filaments debranch at the same rate under 1- to 4-pN pulling forces. For both conditions, branches are exposed to 0.15 µM actin upon the start of the debranching phase. Each individual point is from a single experiment with at least 62 analyzed branches. Debranching rates are obtained from single-exponential fit from survival fraction curves. Error bars are 95% confidence intervals from those fit. Lines represent single-exponential fits from each population of debranching rates.