Fig. 4: PomY condensates wet and bundle PomX filaments in vitro.

a Schematic of the experimental setup. b Representative high-resolution maximum intensity projections of confocal z-stacks of 4 µM PomX-A488 and 4 µM PomY-mCh alone and in combination in the presence of increasing PEG8000 concentrations. White frames, regions shown in zoomed images. White arrows, PomY-mCh condensates. Scale bars, 5 µm. c Quantification of the CV of PomX-A488 fluorescence intensity in images in relation to PomY-mCh and PEG8000 based on the maximum intensity projection of confocal z-stacks. Data from three independent experiments with in total n = 6 analyzed images per condition. All values were normalized to the CV of the 0%PEG8000 and 0 µM PomY-mCh condition. Error bars, mean ± STDEV. d Representative TEM images of 4 µM PomX and 4 µM PomY-mCh in the presence and absence of PEG8000. White frames, regions in zoomed images. Scale bars, 0.5 µm. Experiments were performed three times. e Time-series of PomY-mCh condensates wetting PomX-A488 filament bundles and deforming upon contact (4 µM PomY-mCh, 4 µM PomX-A488, 4% PEG8000) 10 min after mixing of proteins. White arrows, PomY-mCh condensate fusion events, orange arrows, PomY-mCh condensates deforming upon interaction with PomX-A488 filament bundle. Scale bars, 5 µm. See Supplementary Movie 2. Note that in this recording, the PomY-mCh condensates do not stimulate PomX-A488 filament bundle formation, instead the PomX-A488 filament bundle sediments from the solution into the focal plane for imaging. The experiment was performed twice. f Partial FRAP of PomY-mCh on PomX-A488 bundles in the presence of 2% PEG8000. In the diagram, the fluorescence intensity in an ROI was set to 100% before bleaching; the dark magenta line indicates the mean recovery, fitted to a single exponential equation with the light-colored area showing the STDEV from n = 11 bleaching events.