Fig. 3

The A11(+) oligomers bind to the 20S proteasome and impair opening of the substrate gate. a 20S proteasomes (0.4 μg) and pure non-crosslinked Aβ*56 oligomers (1.5 μg) were incubated separately or together for 30 min (37 °C), crosslinked with 1 mM glutaraldehyde for 5 min, and separated by Native-PAGE (4–8% Tris–acetate gel). Total protein was detected by silver stain (left), and total Aβ was detected by western blot (right). b–d The activity of yeast 20S wild-type (WT) and open-gate (α3ΔN) proteasomes was measured for all three proteolytic sites in the presence of A11(+) oligomers from Aβ*56 (b; 2.5 μM), α-Syn (c; 100 nM), and Htt-53Q (d; 50 nM). Chymotrypsin-like activity was measured by LLVY-amc hydrolysis, trypsin-like activity by RLR-amc, and caspase like by nLPnLD-amc hydrolysis. The concentrations of aggregates are calculated based on the respective monomeric peptide/protein mass. All controls contained an equal volume of buffer identical to that of the respective aggregates. The data are representative of three or more independent experiments performed in triplicate. Error bars represent ± standard deviation