A Role of Metastable Regions and Their Connectivity in the Inactivation of a Redox-Regulated Chaperone and Its Inter-Chaperone Crosstalk

Abstract

By modifying the Hsp33's sequence, we reveal that the metastable region has evolved to abolish redox-dependent chaperone activity, rather than enhance binding affinity for client proteins. The intrinsically disordered region of Hsp33 serves as an anchor for the reduced, inactive state of Hsp33, and it dramatically affects the crosstalk with the synergetic chaperone system, DnaK/J. Using mass spectrometry, we describe the role that the metastable region plays in determining client specificity during normal and oxidative stress conditions in the cell. Innovation and Conclusion: We uncover a new role of protein plasticity in Hsp33's inactivation, client specificity, crosstalk with the synergistic chaperone system DnaK/J, and oxidative stress-specific interactions in bacteria. Our results also suggest that Hsp33 might serve as a member of the house-keeping proteostasis machinery, tasked with maintaining a "healthy" proteome during normal conditions, and that this function does not depend on the metastable linker region. Antioxid. Redox Signal. 27, 1252-1267.

Calreticulin: Challenges Posed by the Intrinsically Disordered Nature of Calreticulin to the Study of Its Function

“…In fact, in addition to CALR, several studies have indicated that numerous protein and RNA chaperones are either disordered or contain intrinsically disordered regions needed for their functionality (Tompa and Csermely, 2004 ; Tompa and Kovacs, 2010 ; Kovacs and Tompa, 2012 ). These proteins include late embryogenesis abundant (LEA) and other stress-related plant proteins (Kovacs et al, 2008a , b ; Cuevas-Velazquez et al, 2017 ), human chaperones engaged in neurodegenerative diseases (Uversky, 2011 ), histone chaperones (Liu et al, 2017 ; Warren and Shechter, 2017 ), a redox-regulated chaperone Hsp33 (Rimon et al, 2017 ), small heat shock proteins (Sudnitsyna et al, 2012 ), and the heat shock transcription factors (Westerheide et al, 2012 ).…”

TrypOx, a Novel Eukaryotic Homolog of the Redox-Regulated Chaperone Hsp33 in Trypanosoma brucei

“…Interestingly, the C-terminal domains of the two homologs show low sequence identity of 25%. However, both contain four conserved cysteine residues, oxidation of which leads to the partial unfolding of Hsp33 and exposure of hydrophobic regions crucial for the anti-aggregation activity (Ilbert et al, 2007;Rimon et al, 2017).…”

“…This "perfect match" of the bacterial and TrypOx domains is very unique, as bacterial Hsp33 is a highly dynamic protein, mutation of which leads to either no or constitutive activity. Therefore, wild type-like redox-regulated chaperone and transfer activity can be obtained only by correct interactions between C-terminal, linker, and N-terminal domains (Rimon et al, 2017).…”

“…One of the known crucial chaperones for pathogens’ survival in a hostile environment is the highly conserved, redox-regulated ATP-independent bacterial chaperone Hsp33 ( Jakob et al, 1999 ; Kang et al, 2007 ; Winter et al, 2008 ; Wholey and Jakob, 2012 ; Suss and Reichmann, 2015 ; Krewing et al, 2019 ). Hsp33 is rapidly activated by site-specific oxidation, and serves as a first line of defense during particularly problematic stress conditions that lead to widespread protein unfolding ( Winter et al, 2008 ; Cremers et al, 2010 ; Rimon et al, 2017 ). Oxidation-induced activation of Hsp33 compensates for ATP depletion that inactivates canonical chaperones during oxidative stress, and makes Hsp33 one of the central members of the cellular antioxidant defense system ( Winter et al, 2005 ; Reichmann et al, 2018 ).…”

A molecular switch for Cdc48 activity and localization during oxidative stress and aging

“…It was established that both accumulation of reactive oxygen species and protein misfolding are hallmarks of numerous neurological diseases and aging, thus tying these processes together. Recent studies in our and other labs have reported the discovery of a subgroup of proteinsredox switchesthat use thiol oxidation to mediate diverse physiological functions, including protein quality control 26,27,60 , merging redox and protein homeostasis together.…”