Tuning Hsp104 specificity to selectively detoxify a-synuclein

Hsp104 is an AAA+ protein disaggregase that solubilizes and reactivates proteins trapped in aggregated states. We have engineered potentiated Hsp104 variants to mitigate toxic misfolding of a-synuclein, TDP43, and FUS implicated in fatal neurodegenerative disorders. Though potent disaggregases, these enhanced Hsp104 variants lack substrate specificity and can have unfavorable off-target effects. Here, to lessen off target effects, we engineer substrate-specific Hsp104 variants. By altering Hsp104 pore loops that engage substrate, we disambiguate Hsp104 variants that selectively suppress a-synuclein toxicity but not TDP-43 or FUS toxicity. Remarkably, a-synuclein-specific Hsp104 variants emerge that mitigate a-synuclein toxicity via distinct ATPase-dependent mechanisms involving a-synuclein disaggregation or detoxification of soluble a-synuclein conformers. Importantly, both types of a-synuclein-specific Hsp104 variant reduce dopaminergic neurodegeneration in a C. elegans model of Parkinson's disease more effectively than non-specific variants. We suggest that increasing the substrate specificity of enhanced disaggregases could be applied broadly to tailor therapeutics for neurodegenerative disease.

Automated summary

By engineering substrate-specific variants of the Hsp104 protein, researchers have developed a way to mitigate the toxic misfolding of proteins associated with fatal neurodegenerative disorders. These variants selectively suppress the toxicity of α-synuclein while not affecting the toxicity of TDP-43 or FUS. The specific variants reduce dopamine neuron degeneration more effectively in a Parkinson's disease model compared to non-specific variants.