Control of periplasmic interdomain thiol

disulfide exchange in the transmembrane oxidoreductase DsbD

Despoina A.I. Mavridou, Julie M. Stevens, Alan D. Goddard, Antony C. Willis, Stuart J. Ferguson, Christina Redfield

Research output: Contribution to journalArticle

Abstract

The bacterial protein DsbD transfers reductant from the cytoplasm to the otherwise oxidizing environment of the periplasm. This reducing power is required for several essential pathways, including disulfide bond formation and cytochrome c maturation. DsbD includes a transmembrane domain (tmDsbD) flanked by two globular periplasmic domains (nDsbD/cDsbD); each contains a cysteine pair involved in electron transfer via a disulfide exchange cascade. The final step in the cascade involves reduction of the Cys 103-Cys 109 disulfide of nDsbD by Cys 461 of cDsbD. Here we show that a complex between the globular periplasmic domains is trapped in vivo only when both are linked by tmDsbD. We have found previously (Mavridou, D. A., Stevens, J. M., Ferguson, S. J., & Redfield, C. (2007) J. Mol. Biol. 370, 643-658) that the attacking cysteine (Cys 461) in isolated cDsbD has a high pK a value (10.5) that makes this thiol relatively unreactive toward the target disulfide in nDsbD. Here we show using NMR that active-site pK a values change significantly when cDsbD forms a complex with nDsbD. This modulation of pK a values is critical for the specificity and function of cDsbD. Uncomplexed cDsbD is a poor nucleophile, allowing it to avoid nonspecific reoxidation; however, in complex with nDsbD, the nucleophilicity of cDsbD increases permitting reductant transfer. The observation of significant changes in active-site pK a values upon complex formation has wider implications for understanding reactivity in thiol:disulfide oxidoreductases.

Original languageEnglish
Pages (from-to)3219-3226
Number of pages8
JournalJournal of Biological Chemistry
Volume284
Issue number5
Early online date12 Nov 2008
DOIs
Publication statusPublished - 30 Jan 2009

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Sulfhydryl Compounds
Disulfides
Oxidoreductases
Reducing Agents
Cysteine
Catalytic Domain
Protein Disulfide Reductase (Glutathione)
Periplasm
Nucleophiles
Bacterial Proteins
Cytochromes c
Cytoplasm
Nuclear magnetic resonance
Observation
Modulation
Electrons

Bibliographical note

© 2009, The American Society for Biochemistry and Molecular Biology, Inc.
Author's Choice Creative Commons Attribution Non-Commercial License applies to Author Choice Articles

Cite this

Mavridou, Despoina A.I. ; Stevens, Julie M. ; Goddard, Alan D. ; Willis, Antony C. ; Ferguson, Stuart J. ; Redfield, Christina. / Control of periplasmic interdomain thiol : disulfide exchange in the transmembrane oxidoreductase DsbD. In: Journal of Biological Chemistry. 2009 ; Vol. 284, No. 5. pp. 3219-3226.
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Control of periplasmic interdomain thiol : disulfide exchange in the transmembrane oxidoreductase DsbD. / Mavridou, Despoina A.I.; Stevens, Julie M.; Goddard, Alan D.; Willis, Antony C.; Ferguson, Stuart J.; Redfield, Christina.

In: Journal of Biological Chemistry, Vol. 284, No. 5, 30.01.2009, p. 3219-3226.

Research output: Contribution to journalArticle

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AU - Mavridou, Despoina A.I.

AU - Stevens, Julie M.

AU - Goddard, Alan D.

AU - Willis, Antony C.

AU - Ferguson, Stuart J.

AU - Redfield, Christina

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