The Hsp104 N-Terminal Domain Enables Disaggregase Plasticity and Potentiation

The structural basis by which Hsp104 dissolves disordered aggregates and prions is unknown. A single subunit within the Hsp104 hexamer can solubilize disordered aggregates, whereas prion dissolution requires collaboration by multiple Hsp104 subunits. Here, we establish that the poorly understood Hsp104 N-terminal domain (NTD) enables this operational plasticity. Hsp104 lacking the NTD (Hsp104ΔN) dissolves disordered aggregates but cannot dissolve prions or be potentiated by activating mutations. We define how Hsp104ΔN invariably stimulates Sup35 prionogenesis by fragmenting prions without solubilizing Sup35, whereas Hsp104 couples Sup35 prion fragmentation and dissolution. Volumetric reconstruction of Hsp104 hexamers in ATPγS, ADP-AlFx (hydrolysis transition state mimic), and ADP via small-angle X-ray scattering revealed a peristaltic pumping motion upon ATP hydrolysis, which drives directional substrate translocation through the central Hsp104 channel and is profoundly altered in Hsp104ΔN. We establish that the Hsp104 NTD enables cooperative substrate translocation, which is critical for prion dissolution and potentiated disaggregase activity. [Display omitted] •Hsp104 N-terminal domain confers plasticity that is critical for prion dissolution•Detailed mechanism of how Hsp104 engages, fragments, and dissolves Sup35 prions•SAXS reconstructions of Hsp104 hexamers reveal peristaltic pumping mechanism•Hsp104 N-terminal domain is critical for activity of potentiated Hsp104 variants Sweeny et al. employ small-angle X-ray scattering to reveal that a peristaltic pumping mechanism underpins Hsp104 disaggregase activity. They also define the mechanism by which Hsp104 dissolves Sup35 prions and elucidate that the Hsp104 N-terminal domain enables disaggregase plasticity and potentiation.