Figure 2

Suramin induced Tau condensation depends on electrostatic interactions. (a) Representative trDLS of Tau condensation in low salt buffer, with gradient increase of NaCl. trDLS of 25 μM Tau with addition of 25 μM suramin after ~ 7 to 10 min, followed by addition of 150 mM NaCl (at ~ 17 min), and to 300 mM NaCl (at ~ 25 min). The condensates start to dissolve into monomers and larger aggregates upon increasing the ion concentration to 150 mM or higher. Data point radius sizes correspond to DLS amplitudes, which are proportional to the intensity of scattered light of the respective particles. (b) Quantification of salt dependent Tau:suramin condensate radius. Radii of condensates were calculated from 2 independent experiments representing more than 20 data points and are shown as mean ± SEM. Data have been compared by one-way ANOVA with Tukey test for multiple comparison. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001. (c) Representative trDLS of Tau condensation at increasing 1, 6 Hexanediol (1,6 HD). trDLS of 25 μM Tau with addition of 25 μM suramin after ~ 7 to 10 min, followed by addition of 2.5% 1,6-HD (at ~ 30 min) and 10% (at ~ 45 min), and upon increasing the NaCl concentration to 150 mM (at ~ 80 min). The condensates are moderately stable in 1,6 HD but start to dissolve into monomers and larger aggregates upon increasing the ion concentration to 150 mM NaCl. Data points of the radius dimension correspond to DLS amplitudes, which are proportional to the intensity of scattered light of the respective particles. (d) Quantification of 1, 6 Hexanediol (1,6 HD) dependent Tau:suramin condensate radii. Radii of condensates were calculated from 2 independent experiments, representing more than 20 data points and are shown as mean ± SEM. Data have been compared by one-way ANOVA with Tukey test for multiple comparison. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001. (e) Brightfield microscopy of Tau (25 μM):suramin (25 μM) condensates in low salt (10 mM NaCl) and high salt (300 mM NaCl) conditions or with 10% 1,6 Hexanediol; buffer (25 mM HEPES pH 7.4, 10mM NaCl, 1 mM DTT). Scale bar corresponds to 20 μm.