Structural basis for the disaggregase activity and regulation of Hsp104

Abstract

The Hsp104 disaggregase is a two-ring ATPase machine that rescues various forms of non-native proteins including the highly resistant amyloid fibers. The structural-mechanistic underpinnings of how the recovery of toxic protein aggregates is promoted and how this potent unfolding activity is prevented from doing collateral damage to cellular proteins are not well understood. Here, we present structural and biochemical data revealing the organization of Hsp104 from Chaetomium thermophilum at 3.7 Å resolution. We show that the coiled-coil domains encircling the disaggregase constitute a ‘restraint mask’ that sterically controls the mobility and thus the unfolding activity of the ATPase modules. In addition, we identify a mechanical linkage that coordinates the activity of the two ATPase rings and accounts for the high unfolding potential of Hsp104. Based on these findings, we propose a general model for how Hsp104 and related chaperones operate and are kept under control until recruited to appropriate substrates.DOI: http://dx.doi.org/10.7554/eLife.21516.001

Tuning Hsp104 specificity to selectively detoxify α-synuclein

“…Hsp104 A503S is potentiated via disruption of interprotomer contacts between helix L1 and helix L3 of the MD (Gates et al, 2017;Heuck et al, 2016;Tariq et al, 2019;Ye et al, 2020), but was not amenable for tuning substrate specificity ( Figure 1E). Thus, we wondered whether substrate selectivity could be more effectively engineered in a Hsp104 variant potentiated by a different mechanism than Hsp104 A503S .…”

Avidity for Polypeptide Binding by Nucleotide-Bound Hsp104 Structures

“…10,16,17 In contrast, a study of AAA+ protein ClpC with AMPPNP revealed planar ring hexamers in the crystallographic unit. 18 Many electron microscopy (EM) studies of Hsp104 have also shown planar hexameric rings with a variety of bound nucleotides.…”

“…18 Many electron microscopy (EM) studies of Hsp104 have also shown planar hexameric rings with a variety of bound nucleotides. 3,17,19–21 The poorly hydrolyzable ATP analogue, adenosine 5'-(3-thiotriphosphate) (ATP γ S), and ADP have been used to investigate conformation, oligomerization, and protein remodeling activity of wild-type Hsp104, whereas ATP has been used with Hsp104 variants that are deficient in ATP hydrolysis. 22,23 …”

“…3,10,17–21,24 Monomers adopt different conformations within the ring when unligated or ligated with different nucleotides. These studies led to proposed mechanisms of conformational changes throughout the ATP binding and hydrolysis cycle that are mechanistically linked to disaggregase activity.…”

Substrate Discrimination by ClpB and Hsp104

“…Recent studies have indicated that the Hsp104 hexamer may take on a spiral conformation at some point during the protein disaggregation process (Heuck et al, 2016; Yokom et al, 2016). Spirals have been observed previously when ClpA and ClpB were crystalized (Guo et al, 2002; Lee et al, 2003), however the importance of a spiral vs. closed ring architecture is not yet understood.…”