title: Multiple redox and non-redox interactions define 2-Cys peroxiredoxin as a regulatory hub in the chloroplast.
abstract: In plants, the highly abundant 2-cysteine peroxiredoxin (2-CysPrx) is associated with the chloroplast and involved in protecting photosynthesis. This work addresses the multiple interactions of the 2-CysPrx in the chloroplast, which depend on its redox state. Transcript co-regulation analysis showed a strong linkage to the peptidyl-prolyl-cis/trans isomerase Cyclophilin 20-3 (Cyp20-3) and other components of the photosynthetic apparatus. Co-expression in protoplasts and quantification of fluorescence resonance energy transfer (FRET) efficiency in vivo confirmed protein interactions of 2-CysPrx with Cyp20-3 as well as NADPH-dependent thioredoxin reductase C (NTRC), while thioredoxin x (Trx-x) did not form complexes that could enable FRET. Likewise, changes in FRET of fluorescently labeled 2-CysPrx in vitro and in vivo proved redox dependent dynamics of 2-CysPrx. Addition of Cyp20-3 to an in vitro peroxidase assay with 2-CysPrx had no significant effect on peroxide reduction. Also, in the presence of NTRC, addition of Cyp20-3 did not further enhance peroxide reduction. In addition, 2-CysPrx functioned as chaperone and inhibited aggregation of citrate synthase during heat treatment. This activity was partly inhibited by Cyp20-3. As a new interaction partner of decameric 2-CysPrx, photosystem II could be identified after chloroplast fractionation and in pull-down assays after reconstitution. In summary, the data indicate a dynamic function of plant 2-CysPrx as redox sensor, chaperone, and regulator in the chloroplast with diverse functions beyond its role as thiol peroxidase.
authors.affiliation: Biochemistry and Physiology of Plants, W5-134, Bielefeld University, 33501 Bielefeld, Germany.
authors.forename: Meenakumari
authors.initials: M
authors.lastname: Muthuramalingam
authors.forename: Thorsten
authors.initials: T
authors.lastname: Seidel
authors.forename: Miriam
authors.initials: M
authors.lastname: Laxa
authors.forename: Susana M
authors.initials: SM
authors.lastname: Nunes de Miranda
authors.forename: Florian
authors.initials: F
authors.lastname: Gärtner
authors.forename: Elke
authors.initials: E
authors.lastname: Ströher
authors.forename: Andrea
authors.initials: A
authors.lastname: Kandlbinder
authors.forename: Karl-Josef
authors.initials: KJ
authors.lastname: Dietz
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D002736:Chloroplasts / Q000235:genetics / Q000502:physiology*; D003545:Cysteine / Q000378:metabolism; D017931:DNA Primers; D031541:Fluorescence Resonance Energy Transfer; D007700:Kinetics; D008027:Light; D009249:NADP / Q000378:metabolism; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D054464:Peroxiredoxins / Q000235:genetics* / Q000378:metabolism*; D010766:Phosphorylation; D010788:Photosynthesis; D045331:Photosystem I Protein Complex / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D017931:DNA Primers; D045331:Photosystem I Protein Complex; D009249:NADP; D000255:Adenosine Triphosphate; D054464:Peroxiredoxins; D003545:Cysteine