Fig. 8. Time-resolved SAXS data demonstrate a fast assembly of ANTH and ENTH domains in solution.

a Buffer-corrected SAXS curves for the time-resolved measurements of the complex formation between ANTH and ENTH in presence of 200 μM PIP₂. For a better visibility, the data were smoothed with a Savitzky-Golay filter (51-point window, 2^nd order polynomial). Delay times are color-coded from 0 ms in blue to 1200 ms in dark red. The shape of the curve changes dramatically from the initial time points after 400 ms when the curve stabilizes. b Evolution of the R_g² data of the time-resolved SAXS data set over time. After 500 ms the R_g is relatively constant in all curves. A single exponential fitting was performed and the half-time obtained was ~91 ms. c Volume fractions of DAMMIX obtained using the SAXS curves. The contribution of the unknown component is labeled as “Intermediate”. The volume fractions were fitted to a bi-exponential function to obtain the time constants (fast constant ~8 ms, slow constant around ~150 ms). d DAMMIX ab initio model obtained for the intermediate component vs AENTH tetramer structure from the 16-mer cryoEM map solved. The dimensions of the tetramer and the DAMMIX ab initio model are rather similar, which could indicate that the unknown component of the SAXS data could be tetramers forming in a solution that later on assemble further into larger oligomeric states.