Thioredoxin and Glutaredoxin Systems in Plants: Molecular Mechanisms, Crosstalks, and Functional Significance

Abstract

Thioredoxins (Trx) and glutaredoxins (Grx) constitute families of thiol oxidoreductases. Our knowledge of Trx and Grx in plants has dramatically increased during the last decade. The release of the Arabidopsis genome sequence revealed an unexpectedly high number of Trx and Grx genes. The availability of several genomes of vascular and nonvascular plants allowed the establishment of a clear classification of the genes and the chronology of their appearance during plant evolution. Proteomic approaches have been developed that identified the putative Trx and Grx target proteins which are implicated in all aspects of plant growth, including basal metabolism, iron/sulfur cluster formation, development, adaptation to the environment, and stress responses. Analyses of the biochemical characteristics of specific Trx and Grx point to a strong specificity toward some target enzymes, particularly within plastidial Trx and Grx. In apparent contradiction with this specificity, genetic approaches show an absence of phenotype for most available Trx and Grx mutants, suggesting that redundancies also exist between Trx and Grx members. Despite this, the isolation of mutants inactivated in multiple genes and several genetic screens allowed the demonstration of the involvement of Trx and Grx in pathogen response, phytohormone pathways, and at several control points of plant development. Cytosolic Trxs are reduced by NADPH-thioredoxin reductase (NTR), while the reduction of Grx depends on reduced glutathione (GSH). Interestingly, recent development integrating biochemical analysis, proteomic data, and genetics have revealed an extensive crosstalk between the cytosolic NTR/Trx and GSH/Grx systems. This crosstalk, which occurs at multiple levels, reveals the high plasticity of the redox systems in plants.

Thioredoxin 1 Is Inactivated Due to Oxidation Induced by Peroxiredoxin under Oxidative Stress and Reactivated by the Glutaredoxin System

“…In fact, the cross-talk between the Trx and Grx systems with the catalytic disulfide of some plant Trxs reduced by the Grx systems has been reported previously, such as poplar Trx h4 (33,34), Arabidopsis thaliana Trx h9 (35), and grape Trx h (Vitis vinifera CxxS2) (36). According to the authors, the reduction of plant Trx by the Grx system is a deglutathionylation reaction (37), which is as same as the mechanism proposed in our study.…”

TheArabidopsis thalianaTCP transcription factors: A broadening horizon beyond development

“…With the exception of SO 3 H, all the other oxidized forms of cysteine residues can be reversibly reduced by glutaredoxins (GRXs), thioredoxins (TRXs) or sulfiredoxins (SRXs). [113][114][115][116] A large body of evidence indicates that plant transcription factors involved in stress acclimation and development can operate as direct targets of these posttranslational modifications. 98,117,118 Several different mechanisms are employed by plants to achieve the redox control of transcription factor activities, which encompass redox-modulated subcellular compartmentation, redox-regulated conformational changes, redox-controlled assembly with coregulators, oxidative disassembly of metal-sulfur clusters, indirect redox effects on posttranslational modifications, redox-triggered proteolytic processing, and direct control of DNA binding.…”

Proteomic changes in maize as a response to heavy metal (lead) stress revealed by iTRAQ quantitative proteomics

“…In plants, cellular redox homeostasis can sense and transfer reducing equivalents to numerous target proteins, which is maintained by NAD(P) H-dependent thioredoxin and glutaredoxin systems and involved in various adverse environments (Meyer et al, 2012). In addition, several studies have revealed that glutathione (GSH) acts as an important protection system against metal stress in plants.…”