Abstract

ATP-independent chaperones are usually considered to be holdases that rapidly bind to non-native states of substrate proteins and prevent their aggregation. These chaperones are thought to release their substrate proteins prior to their folding. Spy is an ATP-independent chaperone that acts as an aggregation inhibiting holdase but does so by allowing its substrate proteins to fold while they remain continuously chaperone bound, thus acting as a foldase as well. The attributes that allow such dual chaperoning behavior are unclear. Here, we used the topologically complex protein apoflavodoxin to show that the outcome of Spy’s action is substrate specific and depends on its relative affinity for different folding states. Tighter binding of Spy to partially unfolded states of apoflavodoxin limits the possibility of folding while bound, converting Spy to a holdase chaperone. Our results highlight the central role of the substrate in determining the mechanism of chaperone action.

Spy is an ATP independent chaperone that can act as both a holdase and a foldase towards topologically simple substrates. Assessing the interaction of Spy and apoflavodoxin, a complex client, the authors show that Spy’s activity is substrate specific. Spy binds partially unfolded states of apoflavodoxin tightly, which limits the possibility of folding and converts Spy to a pure holdase.

Details

Title
Mechanism of the small ATP-independent chaperone Spy is substrate specific
Author
Mitra Rishav 1 ; Gadkari, Varun V 2 ; Meinen, Ben A 1 ; van Mierlo Carlo P M 3   VIAFID ORCID Logo  ; Ruotolo, Brandon T 2   VIAFID ORCID Logo  ; Bardwell James C A 1 

 University of Michigan, Howard Hughes Medical Institute, Ann Arbor, USA (GRID:grid.214458.e) (ISNI:0000000086837370); University of Michigan, Department of Molecular, Cellular, and Developmental Biology, Ann Arbor, USA (GRID:grid.214458.e) (ISNI:0000000086837370) 
 University of Michigan, Department of Chemistry, Ann Arbor, USA (GRID:grid.214458.e) (ISNI:0000000086837370) 
 Wageningen University, Laboratory of Biochemistry, Wageningen, The Netherlands (GRID:grid.4818.5) (ISNI:0000 0001 0791 5666) 
Publication year
2021
Publication date
2021
Publisher
Nature Publishing Group
e-ISSN
20411723
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2487154763
Copyright
© The Author(s) 2021. This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.