The role of glutathione in periplasmic redox homeostasis and oxidative protein folding in \(\textit {Escherichia coli}\)

  • The thiol redox balance in the periplasm of \(\textit {E. coli}\) depends on the DsbA/B pair for oxidative power and the DsbC/D system as its complement for isomerization of non-native disulfides. While the standard redox potentials of those systems are known, the \(\textit {in vivo}\) "steady state" redox potential imposed onto protein thiol disulfide pairs in the periplasm remains unknown. Here, we used genetically encoded redox probes (roGFP2 and roGFP-iL), targeted to the periplasm, to directly probe the thiol redox homeostasis in this compartment. These probes contain two cysteine residues that are virtually completely reduced in the cytoplasm, but once exported into the periplasm, can form a disulfide bond, a process that can be monitored by fluorescence spectroscopy. Even in the absence of DsbA, roGFP2, exported to the periplasm, was almost fully oxidized, suggesting the presence of an alternative system for the introduction of disulfide bonds into exported proteins. However, the absence of DsbA shifted the steady state periplasmic thiol-redox potential from −228 mV to a more reducing −243 mV and the capacity to re-oxidize periplasmic roGFP2 after a reductive pulse was significantly decreased. Re-oxidation in a DsbA strain could be fully restored by exogenous oxidized glutathione (GSSG), while reduced GSH accelerated re-oxidation of roGFP2 in the WT. In line, a strain devoid of endogenous glutathione showed a more reducing periplasm, and was significantly worse in oxidatively folding PhoA, a native periplasmic protein and substrate of the oxidative folding machinery. PhoA oxidative folding could be enhanced by the addition of exogenous GSSG in the WT and fully restored in a ΔdsbA mutant. Taken together this suggests the presence of an auxiliary, glutathione-dependent thiol-oxidation system in the bacterial periplasm.

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Author:Lisa KnokeGND, Jannik ZimmermannGND, Natalie LupilovGND, Jannis Frederic SchneiderGND, Beyzanur CelebiGND, Bruce MorganGND, Lars I. LeichertORCiDGND
Parent Title (English):Redox biology
Place of publication:Amsterdam
Document Type:Article
Date of Publication (online):2024/01/31
Date of first Publication:2023/06/26
Publishing Institution:Ruhr-Universität Bochum, Universitätsbibliothek
Tag:Open Access Fonds
Disulfide; DsbA; Glutathione; Oxidative folding; Periplasm; roGFP
Issue:Article 102800
First Page:102800-1
Last Page:102800-13
Article Processing Charge funded by the Deutsche Forschungsgemeinschaft (DFG) and the Open Access Publication Fund of Ruhr-Universität Bochum.
Institutes/Facilities:Institut für Biochemie und Pathobiochemie
Dewey Decimal Classification:Naturwissenschaften und Mathematik / Biowissenschaften, Biologie, Biochemie
open_access (DINI-Set):open_access
faculties:Medizinische Fakultät
Licence (English):License LogoCreative Commons - CC BY 4.0 - Attribution 4.0 International