RT Journal Article
SR Electronic
T1 Syntaxin-6 delays prion protein fibril formation and prolongs presence of toxic aggregation intermediates
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2022.08.25.505283
DO 10.1101/2022.08.25.505283
A1 Sangar, Daljit
A1 Hill, Elizabeth
A1 Jack, Kezia
A1 Batchelor, Mark
A1 Mistry, Beenaben
A1 Ribes, Juan M.
A1 Jackson, Graham S.
A1 Mead, Simon
A1 Bieschke, Jan
YR 2023
UL http://biorxiv.org/content/early/2023/09/21/2022.08.25.505283.abstract
AB Prions replicate via the autocatalytic conversion of cellular prion protein (PrPC) into fibrillar assemblies of misfolded PrP. While this process has been extensively studied in vivo and in vitro, non-physiological reaction conditions of fibril formation in vitro have precluded the identification and mechanistic analysis of cellular proteins, which may alter PrP self-assembly and prion replication. Here, we have developed a fibril formation assay for recombinant murine and human PrP (23-231) under near-native conditions (NAA) to study the effect of cellular proteins, which may be risk factors or potential therapeutic targets in prion disease. Genetic screening suggests that variants that increase syntaxin-6 expression in the brain (gene: STX6) are risk factors for sporadic Creutzfeldt-Jakob disease (CJD). Analysis of the protein in NAA revealed counterintuitively that syntaxin-6 is a potent inhibitor of PrP fibril formation. It significantly delayed the lag phase of fibril formation at highly sub-stoichiometric molar ratios. However, when assessing toxicity of different aggregation time points to primary neurons, syntaxin-6 prolonged the presence of neurotoxic PrP species. Electron microscopy and super-resolution fluorescence microscopy revealed that, instead of highly ordered fibrils, in the presence of syntaxin-6 PrP formed less-ordered aggregates containing syntaxin-6. These data strongly suggest that the protein can directly alter the initial phase of PrP self-assembly and, uniquely, can act as an ‘anti-chaperone’, which promotes toxic aggregation intermediates by inhibiting fibril formation.Competing Interest StatementThe authors have declared no competing interest.