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Chaperones Skp and SurA dynamically expand unfolded OmpX and synergistically disassemble oligomeric aggregates.

Published version
Peer-reviewed

Type

Article

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Authors

Abstract

Periplasmic chaperones 17-kilodalton protein (Skp) and survival factor A (SurA) are essential players in outer membrane protein (OMP) biogenesis. They prevent unfolded OMPs from misfolding during their passage through the periplasmic space and aid in the disassembly of OMP aggregates under cellular stress conditions. However, functionally important links between interaction mechanisms, structural dynamics, and energetics that underpin both Skp and SurA associations with OMPs have remained largely unresolved. Here, using single-molecule fluorescence spectroscopy, we dissect the conformational dynamics and thermodynamics of Skp and SurA binding to unfolded OmpX and explore their disaggregase activities. We show that both chaperones expand unfolded OmpX distinctly and induce microsecond chain reconfigurations in the client OMP structure. We further reveal that Skp and SurA bind their substrate in a fine-tuned thermodynamic process via enthalpy-entropy compensation. Finally, we observed synergistic activity of both chaperones in the disaggregation of oligomeric OmpX aggregates. Our findings provide an intimate view into the multifaceted functionalities of Skp and SurA and the fine-tuned balance between conformational flexibility and underlying energetics in aiding chaperone action during OMP biogenesis.

Description

Keywords

chaperones, disaggregation, outer membrane protein biogenesis, protein folding, single-molecule FRET, Bacterial Outer Membrane Proteins, Biopolymers, Fluorescence Resonance Energy Transfer, Molecular Chaperones, Protein Conformation

Journal Title

Proc Natl Acad Sci U S A

Conference Name

Journal ISSN

0027-8424
1091-6490

Volume Title

119

Publisher

Proceedings of the National Academy of Sciences
Sponsorship
European Commission Horizon 2020 (H2020) Marie Sk?odowska-Curie actions (841466)