Rheostat re-wired: alternative hypotheses for the control of thioredoxin reduction potentials
| Autor: | Sean Elliott, Rebekah E. Bjork, Catherine L. Drennan, Sangha Mitra, Kathryn D. Bewley, Mishtu Dey, Sarah E. Chobot |
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| Přispěvatelé: | Massachusetts Institute of Technology. Department of Biology, Massachusetts Institute of Technology. Department of Chemical Engineering, Massachusetts Institute of Technology. Department of Chemistry, Dey, Mishtu, Bjork, Rebekah E., Drennan, Catherine L. |
| Jazyk: | angličtina |
| Rok vydání: | 2015 |
| Předmět: |
Protein Folding
lcsh:Medicine Crystallography X-Ray Redox Thioredoxins Denaturation (biochemistry) lcsh:Science chemistry.chemical_classification Multidisciplinary Chemistry lcsh:R Archaea Glutathione 3. Good health Amino acid Thioredoxin reduction Folding (chemistry) Biochemistry Mutagenesis Site-Directed Unfolded protein response Biophysics Thermodynamics Protein folding lcsh:Q Thioredoxin Oxidation-Reduction Research Article |
| Zdroj: | PLoS ONE, Vol 10, Iss 4, p e0122466 (2015) Public Library of Science PLoS ONE |
| ISSN: | 1932-6203 |
| Popis: | Thioredoxins are small soluble proteins that contain a redox-active disulfide (CXXC). These disulfides are tuned to oxidizing or reducing potentials depending on the function of the thioredoxin within the cell. The mechanism by which the potential is tuned has been controversial, with two main hypotheses: first, that redox potential (E[subscript m]) is specifically governed by a molecular ‘rheostat’—the XX amino acids, which influence the Cys pK[subscript a] values, and thereby, E[subscript m]; and second, the overall thermodynamics of protein folding stability regulates the potential. Here, we use protein film voltammetry (PFV) to measure the pH dependence of the redox potentials of a series of wild-type and mutant archaeal Trxs, PFV and glutathionine-equilibrium to corroborate the measured potentials, the fluorescence probe BADAN to measure pK[subscript a] values, guanidinium-based denaturation to measure protein unfolding, and X-ray crystallography to provide a structural basis for our functional analyses. We find that when these archaeal thioredoxins are probed directly using PFV, both the high and low potential thioredoxins display consistent 2H+:2e- coupling over a physiological pH range, in conflict with the conventional ‘rheostat’ model. Instead, folding measurements reveals an excellent correlation to reduction potentials, supporting the second hypothesis and revealing the molecular mechanism of reduction potential control in the ubiquitous Trx family. National Science Foundation (U.S.) (MCB 1122977) |
| Databáze: | OpenAIRE |
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