Fig. 2: ATP hydrolysis by Hsp104 counteract starvation-induced protein aggregation.
From: ATP hydrolysis by yeast Hsp104 determines protein aggregate dissolution and size in vivo
a In cells expressing Hsp104E285Q mutant, percentage of cells bearing aggregates is strongly increased in optimal conditions of 2% glucose and increases further in 0.2% and 0.02% glucose. Treatment with ATP (in the presence of DMSO) does not lead to aggregate dissolution. b In cells expressing Hsp104E687Q mutant, percentage of cells bearing aggregates is increased in optimal conditions of 2% glucose and increases further in 0.2% and 0.02% glucose medium. Treatment with ATP (in the presence of DMSO) does not lead to aggregate dissolution. In panels a and b, n = 1200 cells were screened for aggregates starting from three independent exponential yeast cultures for each condition. Data are mean ± SD from at least three independent cultures, each performed in triplicate, and the means of technical replicates are represented as individual data points. ***p < 0.001; **p < 0.01; *p < 0.05 (one-way ANOVA plus Tukey post hoc). d Mean aggregate diameter shifts to larger sizes during starvation in 0.2% and 0.02% glucose in Hsp104E285Q mutant. The addition of ATP (in the presence of DMSO) did not result in aggregates reverting to the sizes observed in control conditions. Red arrows point to vacuolar localization of the signal and represent structures that were not taken into account during image analysis. Data represent binned values of individual aggregate diameters for N = 185, 200, 199, 200, 200 aggregates from three independent exponential yeast cultures for each condition: 2%, 0.2%, and 0.02% glucose, 0.2% glucose + ATP, 0.02% glucose + ATP, respectively. Mean aggregate diameter shifts to larger sizes during starvation in 0.2% and 0.02% glucose in Hsp104E687Q mutant. The addition of ATP (in the presence of DMSO) did not result in aggregates reverting to the sizes observed in control conditions. Data represent binned values of individual aggregate diameters for N = 200 aggregates from three independent exponential yeast cultures for each condition. In panels c and d, Kolmogorov–Smirnov test was used to compare the statistical significance of the observed differences between each studied condition and the control (2% glucose) (***p < 0.001; **p < 0.01; *p < 0.05). The images are representative of three biological replicates, each in three technical replicates. The black bar represents 8 µm.
