title: Redox-Dependent Conformational Dynamics of Decameric 2-Cysteine Peroxiredoxin and its Interaction with Cyclophilin 20-3.
abstract: 2-Cysteine peroxiredoxins (2-CysPrxs) switch between functions as a thiol peroxidase, chaperone, an interaction partner and possibly a proximity-based oxidase in a redox-dependent manner. In photosynthetic eukaryotes, 2-CysPrx localizes to the plastid, functions in the context of photosynthesis and enables an ascorbate peroxidase-independent water-water cycle for detoxifying H2O2The high degree of evolutionary conservation of 2-CysPrx suggests that the switching is an essential characteristic and needed to transduce redox information to downstream pathways and regulation. The study aimed at exploring the dissociation behavior of 2-CysPrx and its interactions with cyclophilin depending on bulk phase conditions. Isothermal titration microcalorimetry (ITC), dynamic light scattering and size exclusion chromatography (SEC) proved the previously suggested model that reduced 2-CysPrx below a critical transition concentration (CTC) exists in its dimeric state, and above the CTC adopts the decameric state. The presence of cyclophilin 20-3 (Cyp20-3) affected the CTC of a 2-CysPrx decamer suggesting interaction which was further quantified by direct titration of 2-CysPrx with Cyp20-3, and in overlays. Finally catalytic inactivation assays showed the higher catalytic efficiency of 2-CysPrx at pH 8 compared with pH 7.2, but also revealed increased inactivation by hyperoxidation at pH 8. Interestingly, calculation of the average turnover number until inactivation gave rather similar values of 243 and 268 catalytic cycles at pH 8 and pH 7.2, respectively. These quantitative data support a model where 2-CysPrx and Cyp20-3, by interaction, form a redox-sensitive regulatory module in the chloroplast which is under control of the photosynthesis-linked stromal pH value, the redox state and additional stromal protein factor(s).
authors.affiliation: Department of Biochemistry and Physiology of Plants, Faculty of Biology, University of Bielefeld, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Liebthal
authors.affiliation: Department of Biochemistry and Physiology of Plants, Faculty of Biology, University of Bielefeld, Germany.
authors.forename: Marcel
authors.initials: M
authors.lastname: Strüve
authors.affiliation: Department of Biochemistry and Physiology of Plants, Faculty of Biology, University of Bielefeld, Germany.
authors.forename: Xin
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Physical and Biophysical Chemistry, Faculty of Chemistry, University of Bielefeld, Germany.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Hertle
authors.affiliation: Department of Biochemistry and Physiology of Plants, Faculty of Biology, University of Bielefeld, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Maynard
authors.affiliation: Department of Physical and Biophysical Chemistry, Faculty of Chemistry, University of Bielefeld, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Hellweg
authors.affiliation: Department of Biochemistry and Physiology of Plants, Faculty of Biology, University of Bielefeld, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Viehhauser
authors.affiliation: Department of Biochemistry and Physiology of Plants, Faculty of Biology, University of Bielefeld, Germany karl-josef.dietz@uni-bielefeld.de.
authors.forename: Karl-Josef
authors.initials: KJ
authors.lastname: Dietz
mesh_terms: D017360:Arabidopsis / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000378:metabolism*; D002151:Calorimetry; D002850:Chromatography, Gel; D021983:Cyclophilins / Q000378:metabolism*; D000067493:Dynamic Light Scattering; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008954:Models, Biological; D010084:Oxidation-Reduction; D054464:Peroxiredoxins / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D055503:Protein Multimerization; D013816:Thermodynamics
chemical_list: D029681:Arabidopsis Proteins; C493631:2-Cys peroxiredoxin A, Arabidopsis; D054464:Peroxiredoxins; D021983:Cyclophilins; C000616093:cyclophilin 20-3, Arabidopsis
keywords: 2-Cysteine Peroxiredoxin; cyclophilin; interaction; isothermal titration calorimetry; peroxiredoxin; photosynthesis; redox regulation