Function and Regulation of Chloroplast Peroxiredoxin IIE.

Anna Dreyer,Patrick Treffon,Anna Maria Jozefowicz,Hans-Peter Mock,Andrea Matros,Daniel Basiry,Karl-Josef Dietz

doi:10.3390/antiox10020152

Anna Dreyer, Patrick Treffon + Show 5 more

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https://doi.org/10.3390/antiox10020152

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Abstract

Peroxiredoxins (PRX) are thiol peroxidases that are highly conserved throughout all biological kingdoms. Increasing evidence suggests that their high reactivity toward peroxides has a function not only in antioxidant defense but in particular in redox regulation of the cell. Peroxiredoxin IIE (PRX-IIE) is one of three PRX types found in plastids and has previously been linked to pathogen defense and protection from protein nitration. However, its posttranslational regulation and its function in the chloroplast protein network remained to be explored. Using recombinant protein, it was shown that the peroxidatic Cys121 is subjected to multiple posttranslational modifications, namely disulfide formation, S-nitrosation, S-glutathionylation, and hyperoxidation. Slightly oxidized glutathione fostered S-glutathionylation and inhibited activity in vitro. Immobilized recombinant PRX-IIE allowed trapping and subsequent identification of interaction partners by mass spectrometry. Interaction with the 14-3-3 υ protein was confirmed in vitro and was shown to be stimulated under oxidizing conditions. Interactions did not depend on phosphorylation as revealed by testing phospho-mimicry variants of PRX-IIE. Based on these data it is proposed that 14-3-3υ guides PRX‑IIE to certain target proteins, possibly for redox regulation. These findings together with the other identified potential interaction partners of type II PRXs localized to plastids, mitochondria, and cytosol provide a new perspective on the redox regulatory network of the cell.

Highlights

Chloroplasts of cormophytes contain three types of peroxiredoxins (PRXs), namely classical 2-cysteine peroxiredoxin (2-CysPRX), a bacteroferritin-comigratory protein homolog PRX-Q and a type II peroxiredoxin named Peroxiredoxin IIE (PRX-IIE) [1,2]
The catalytic activity of 2-CysPRX, PRX-Q, and type II PRX relies on a conserved second cysteine, which acts as resolving thiol (CysR )
To confirm the subcellular localization of PRXIIE, a plasmid encoding the PRX-IIE-EYFP fusion protein was transfected into mesophyll protoplasts

Summary

Introduction

Chloroplasts of cormophytes contain three types of peroxiredoxins (PRXs), namely classical 2-cysteine peroxiredoxin (2-CysPRX), a bacteroferritin-comigratory protein homolog PRX-Q and a type II peroxiredoxin named PRX-IIE [1,2]. They possess a peroxidatic cysteinyl thiol (CysP ) with a very low pK value and expose the deprotonated thiolate anion in a conserved catalytic environment. Because of this particular feature, PRXs function as highly affine and efficient thiol peroxidases [4]. The catalytic activity of 2-CysPRX, PRX-Q, and type II PRX relies on a conserved second cysteine, which acts as resolving thiol (CysR ). Upon reaction with the Antioxidants 2021, 10, 152.

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