Heat shock protein 104 inhibited the fibrillization of prion peptide 106-126 and disassembled prion peptide 106-126 fibrils in vitro

Amyloid-like fibrils have been associated with the pathogenesis of human prion diseases. Prion peptide of aa 106-126 (PrP106-126) exhibits many PrPSc-like biochemical features, forming amyloid-like fibrils in vitro. Here, we found that the recombinant yeast-derived molecular chaperon Hsp104 inhibited significantly the fibril assembly of the synthetic PrP106-126 peptide by dynamic ThT assays in vitro. EM assays revealed almost no fibril-like structure after incubation of the synthetic PrP106-126 peptides with Hsp104 for 12 h. Circular dichroism assays identified that treatment of Hsp104 shifted the secondary structure of PrP106-126 fibrils from β-sheet to a random coil. MTT tests confirmed that interaction of PrP106-126 with Hsp104 maintained the toxicity of PrP106-126 on human neuroblastoma cell line SK-N-SH. Additionally, Hsp104 was able to disassemble the mature PrP106-126 fibrils in vitro, leading to recovering the cytotoxicity of PrP106-126 on SK-N-SH cells. Our study provides the molecular evidences that the yeast-derived Hsp104 can interfere in the fibril assembly and disassembly of human PrP106-126 segment.