1. Theoretical insights into the mechanism of redox switch in heat shock protein Hsp33
- Author
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Mironel Enescu, Bruno Cardey, Rima Kassim, Christophe Ramseyer, Laboratoire Chrono-environnement ( LCE ), Université Bourgogne Franche-Comté ( UBFC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Franche-Comté ( UFC ), Laboratoire Chrono-environnement - CNRS - UFC (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Laboratoire de Physique Moléculaire (LPM), Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Laboratoire de Physique Moléculaire ( LPM ), and Centre National de la Recherche Scientifique ( CNRS ) -Université de Franche-Comté ( UFC )
- Subjects
[ SDV.BBM.BP ] Life Sciences [q-bio]/Biochemistry, Molecular Biology/Biophysics ,Inorganic chemistry ,Hsp33 ,chemistry.chemical_element ,hydrogen peroxide ,Zinc ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Redox ,Dissociation (chemistry) ,Inorganic Chemistry ,03 medical and health sciences ,symbols.namesake ,Reaction rate constant ,energy barrier ,Heat-Shock Proteins ,ComputingMilieux_MISCELLANEOUS ,030304 developmental biology ,0303 health sciences ,Chemistry ,Reaction step ,ab initio ,Escherichia coli Proteins ,0104 chemical sciences ,Gibbs free energy ,[CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry ,[SDV.BBM.BP]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Biophysics ,Crystallography ,redox switch ,[ CHIM.THEO ] Chemical Sciences/Theoretical and/or physical chemistry ,symbols ,Thermodynamics ,Oxidation-Reduction ,Cysteine - Abstract
Heat shock protein 33 (Hsp33) is activated in the presence of H2O2 by a very interesting redox switch based on a tetra-coordinated zinc–cysteine complex present in the fully reduced and inactive protein form. The oxidation of this zinc center by H2O2 induces formation of two S–S bridges and the zinc release followed by the protein unfolding. We report here a theoretical study of the step-by-step sequence of the overall process starting with the oxidation of the first cysteine residue and ending with the zinc release. Each reaction step is characterized by its Gibbs free energy barrier (∆G ‡). It is predicted that the first reaction step consists in the oxidation of Cys263 by H2O2 which is by far the most reactive cysteine (∆G ‡ = 15.4 kcal mol−1). The next two reaction steps are the formation of the first S–S bridge between Cys263 and Cys266 (∆G ‡ = 13.6 kcal mol−1) and the oxidation of Cys231 by H2O2 (∆G ‡ = 20.4 kcal mol−1). It is then shown that the formation of the second S–S bridge (Cys231–Cys233) before the zinc release is most unlikely (∆G ‡ = 34.8 kcal mol−1). Instead, the release of zinc just after the oxidation of the third cysteine (Cys231) is shown to be thermodynamically (dissociation Gibbs free energy ∆G d = 6.0 kcal mol−1) and kinetically (reaction rate constant k d ≈ 106 s−1) favored. This result is in good agreement with the experimental data on the oxidation mechanism of Hsp33 zinc center available to date.
- Published
- 2015
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