Spatial quality control bypasses cell-based limitations on proteostasis to promote prion curing

Abstract

The proteostasis network has evolved to support protein folding under normal conditions and to expand this capacity in response to proteotoxic stresses. Nevertheless, many pathogenic states are associated with protein misfolding, revealing in vivo limitations on quality control mechanisms. One contributor to these limitations is the physical characteristics of misfolded proteins, as exemplified by amyloids, which are largely resistant to clearance. However, other limitations imposed by the cellular environment are poorly understood. To identify cell-based restrictions on proteostasis capacity, we determined the mechanism by which thermal stress cures the [PSI+]/Sup35 prion. Remarkably, Sup35 amyloid is disassembled at elevated temperatures by the molecular chaperone Hsp104. This process requires Hsp104 engagement with heat-induced non-prion aggregates in late cell-cycle stage cells, which promotes its asymmetric retention and thereby effective activity. Thus, cell division imposes a potent limitation on proteostasis capacity that can be bypassed by the spatial engagement of a quality control factor.DOI: http://dx.doi.org/10.7554/eLife.04288.001

Engineering enhanced protein disaggregases for neurodegenerative disease

“…[78][79][80] Thus, amyloid fibrils and toxic oligomers are not intractable and can be eliminated rapidly by Hsp104. 61,73,[77][78][79][80][81][82][83][84]87,91 Inexplicably, Hsp104 has no metazoan ortholog despite being highly conserved in bacteria, plants, fungi, chromista, and protozoa. 39,40,52 The reason for the loss of Hsp104 from metazoan lineages is uncertain, especially as Hsp104 can be expressed safely and broadly in worm, fly, mouse, and rat.…”

Repurposing Hsp104 to Antagonize Seminal Amyloid and Counter HIV Infection

“…Hsp104 renatures amorphous protein aggregates following thermal or chemical stress, and catalytically deconstructs diverse amyloid fibrils (DeSantis et al, 2012; Glover and Lindquist, 1998; Jackrel et al, 2014; Klaips et al, 2014; Liu et al, 2011; Lo Bianco et al, 2008; Shorter and Lindquist, 2004, 2006). Hsp104 is a generalist and is adapted to remodel diverse prion conformers and disaggregate a large proportion of the yeast proteome in response to environmental stress (Vashist et al, 2010).…”

Distinct Prion Domain Sequences Ensure Efficient Amyloid Propagation by Promoting Chaperone Binding or Processing In Vivo

“…Because expression of the more extensive repeat expansion and deletion constructs was toxic (Table 1), we first considered the possibility that the sequence variants might induce a stress response, resulting in altered chaperone levels, substrate load and amyloid fragmentation [61–63]. However, the expression levels of Hsp104 and its co-chaperones Ssa1 (Hsp70) and Sis1 (Hsp40) in our RV and ΔRPR strains were similar to wildtype (Fig 6A).…”

“…For NM-HA and NM-HA-C immunocapture, native lysates were prepared as described [61], and immunocapture was performed using anti-HA magnetic beads or anti-Myc magnetic beads (Thermo Scientific Pierce). Co-captured proteins were resolved by SDS-PAGE and analyzed by western blotting for Sup35, HA (Roche), Hsp104 (Abcam), Ssa1 (gift from E. Craig), and Sis1 (gift from M. Tuite).…”

“…Cell lysates were prepared, and immunocapture was performed as described [61], except 600mM NaCl was used in lysis and wash buffers. Co-captured proteins were separated by SDS-PAGE and analyzed by western blotting for Firefly luciferase (Sigma) and Hsp104 (Abcam).…”