An Extended Active-site Motif Controls the Reactivity of the Thioredoxin Fold |
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Authors: | Despoina A. I. Mavridou Emmanuel Saridakis Paraskevi Kritsiligkou Erin C. Mozley Stuart J. Ferguson Christina Redfield |
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Affiliation: | From the ‡Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom and ;the §Department of Physical Chemistry, N.C.S.R. Demokritos, Aghia Paraskevi, Athens 15310, Greece |
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Abstract: | Proteins belonging to the thioredoxin (Trx) superfamily are abundant in all organisms. They share the same structural features, arranged in a seemingly simple fold, but they perform a multitude of functions in oxidative protein folding and electron transfer pathways. We use the C-terminal domain of the unique transmembrane reductant conductor DsbD as a model for an in-depth analysis of the factors controlling the reactivity of the Trx fold. We employ NMR spectroscopy, x-ray crystallography, mutagenesis, in vivo functional experiments applied to DsbD, and a comparative sequence analysis of Trx-fold proteins to determine the effect of residues in the vicinity of the active site on the ionization of the key nucleophilic cysteine of the -CXXC- motif. We show that the function and reactivity of Trx-fold proteins depend critically on the electrostatic features imposed by an extended active-site motif. |
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Keywords: | NMR Oxidase Reductase Thioredoxin X-ray Crystallography DsbD Electrostatics pKa Values Thiol-Disulfide Exchange Thioredoxin Fold |
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