Prions adopt alternative, self-replicating protein conformations and thereby determine novel phenotypes that are often irreversible. Nevertheless, dominant-negative prion mutants can revert phenotypes associated with some conformations. These observations suggest that, while intervention is possible, distinct inhibitors must be developed to overcome the conformational plasticity of prions. To understand the basis of this specificity, we determined the impact of the G58D mutant of the Sup35 prion on three of its conformational variants, which form amyloids in S . cerevisiae . G58D had been previously proposed to have unique effects on these variants, but our studies suggest a common mechanism. All variants, including those reported to be resistant, are inhibited by G58D but at distinct doses. G58D lowers the kinetic stability of the associated amyloid, enhancing its fragmentation by molecular chaperones, promoting Sup35 resolubilization, and leading to amyloid clearance particularly in daughter cells. Reducing the availability or activity of the chaperone Hsp104, even transiently, reverses curing. Thus, the specificity of inhibition is determined by the sensitivity of variants to the mutant dosage rather than mode of action, challenging the view that a unique inhibitor must be developed to combat each variant. Author summary Prion proteins adopt alternative conformations and assemble into amyloid fibers, which have been associated with human disease. These fibers are highly stable and self-replicate, leading to their persistence and resulting in a set of progressive and often fatal disorders. Inhibitors have been shown to interfere with some conformations but not others, suggesting that distinct strategies must be developed to target each. However, we show here that a single dominant-negative mutant can inhibit multiple conformations of the same prion protein through the same pathway but at distinct doses. Thus, the basis of this specificity is sensitivity rather than resistance to the mechanism of inhibition, suggesting that common strategies may be used to target a range of prion conformations.
【초록키워드】 variant, Intervention, inhibitors, variants, Protein, sensitivity, specificity, stability, cells, persistence, amyloid, pathway, phenotype, mutant, molecular, inhibitor, mechanism, conformations, kinetic, daughter cells, determined by, protein conformations, observation, Phenotypes, human disease, disorders, mode, dosage, conformation, plasticity, doses, Lower, chaperones, prion, clearance, curing, chaperone, Effect, fiber, shown, resulting, reported, inhibit, inhibited, determine, unique, overcome, conformational, interfere, dominant-negative, 【제목키워드】 variant, mutant, inhibit, dominant-negative,