No abstract

Prion-like self-perpetuating conformational conversion of proteins into amyloid aggregates is associated with both transmissible neurodegenerative diseases and non-Mendelian inheritance. Here, we demonstrate that ATP modulates the formation and dissolution of amyloids from a yeast prion domain (NM domain of Saccharomyces cerevisiae Sup35) and restricts autocatalytic amplification by controlling the amount of fragmentable and seeding-competent aggregates. ATP, at (high) physiological concentrations in the presence of Mg2+, kinetically accelerates NM aggregation. Interestingly, ATP also promotes phase-separation-mediated aggregation of a human protein harboring a yeast prion-like domain. We also show that ATP dose independently disaggregates preformed NM fibrils. Furthermore, high concentrations of ATP delimited the number of seeds by generating compact, ATP-bound NM fibrils that exhibited nominal fragmentation by either free ATP or Hsp104 disaggregase. Additionally, (low) pathological ATP concentrations restricted autocatalytic amplification by forming structurally distinct seeding-inefficient amyloids. Our results provide mechanistic underpinnings of concentration-dependent chemical chaperoning by ATP against prion-like transmissions.

No abstract

The prion-like self-perpetuating conformational conversion is involved in both transmissible neurodegenerative diseases and non-Mendelian inheritance traits. The transmissibility of amyloid-like aggregates is dependent on the stoichiometry of chaperones such as heat shock proteins. To provide the mechanistic underpinning of the generation and persistence of prefibrillar amyloid seeds that are critical for the prion-like propagation, we studied the effect of Hsp104 disaggregase on the assembly mechanism of a yeast prion determinant of Saccharomyces cerevisiae Sup35. At low sub-stoichiometric concentrations, Hsp104 exhibits a dual role and considerably accelerates the formation of seeding-competent prefibrillar amyloids by shortening the lag phase but also prolongs their persistence by introducing unusual kinetic halts and delaying their conversion into matured fibers. Hsp104-mediated amyloid species comprise a more ordered packing and display an enhanced autocatalytic self-templating ability compare to amyloids formed without Hsp104. Our findings underscore the key functional and pathological roles of sub-stoichiometric chaperones in prion-like propagation.