Fig. 1: Effect of salt on DNAJB1 binding to αSyn amyloid fibrils.

A Binding assay for WT DNAJB1 binding to αSyn amyloid fibrils in HKMD or HD buffer. Two controls without amyloid fibrils confirm that salt depletion does not cause precipitation of WT DNAJB1. A larger pellet band for DNAJB1 is observed in HD buffer in the presence of fibrils. S: supernatant, P: pellet. B Histogram of WT DNAJB1 bound fractions in each buffer (N = 3 independent experiments). A Shapiro–Wilk test was performed to check the normality of the data, followed by an unpaired t test (P = 0.0016). Mean DNAJB1 binding values with SD are shown. C Cryo micrograph of αSyn amyloid fibrils fully decorated by WT DNAJB1 in HD buffer. Scale bar, 500 Å. D ThT assay showing that pre-incubation of WT DNAJB1 and αSyn amyloid fibrils in HD buffer does not alter the disaggregation activity. The assay was performed in disaggregation buffer (Table 2). Mean normalised ThT fluorescence is shown with SEM. E Binding assay showing the reversibility of the binding when the salts are added back. The proteins were incubated twice in HD buffer (HD condition), twice in HKMD buffer (HKMD condition) or once in HD buffer and once in HKMD buffer (HD/HKMD buffer). F Histogram of the WT DNAJB1 bound fraction in each condition shown in (E) (N = 3 independent experiments). A Shapiro–Wilk test was performed to check the normality of the data, followed by a one-way ANOVA with Tukey’s multiple comparisons test (P = 0.0004 between HD and HD/HKMD conditions, P = 0.0002 between HD and HKMD conditions). Mean DNAJB1 binding values with SD are shown.