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Plant Protective Proteins

Protection and signalization via thiol reductases


Analysis of the physiological functions of thiol reductases, enzymes controlling the redox status of proteins, in plant responses to environmental constraints.

Published on 10 July 2019

 

​ Figure 1: Functions of thiol reductases in plant responses to environmental constraints.
 
 

Reactive oxygen species lead to post-translational modifications that can provoke changes in activity and/or conformation of proteins. These modifications are generally irreversible except in the case of the two sulfur-containing residues, cysteine and methionine. Indeed, the redox status of these amino acids is regulated by a superfamily of enzymes termed thiol reductases and including thioredoxins, glutaredoxins, peroxiredoxins and methionine sulfoxide reductases. These  enzymes, by controlling the redox status of target proteins, play decisive roles in protective and repair mechanisms of photosynthetic structures upon environmental constraints, as shown for the thioredoxin CDSP32 (Chloroplastic Drought-induced Stress Protein of 32 kDa) and methionine sulfoxide reductases (Photograph 1).

Our current research aims at deciphering the roles of thiol reductases in the functioning of stomata, which are leaf pores surrounded by two guard cells that have the capacity to modulate their volume as a function of environmental conditions. Stomata allow gas and water exchange at the leaf surface, and thus condition photosynthetic activity and growth.  Several thiol reductases are abundant in guard cells and the stomatal conductance as well as the leaf temperature is altered in Arabidopsis lines deficient for the expression of the genes coding these reductases. Our objective is to delineate the physiological functions of these reductases and of their partners/targets within the signaling network regulating the functioning of stomata in relation to environmental stimuli.  

Photograph 1: Growth of Arabidopsis plants, WT (left) or lacking plastidial MSRBs (right), under high light (500 µmoles photons m-2.s-1) . © Pascal Rey
 

We also showed the involvement of glutaredoxins GRXS14 and GRXS17 in light-dependent signal transduction pathways controlling development (Photograph 2).

Photograph 2: Development of Arabidopsis plants, WT (left) or deficient in GRXS17 (right), under long photoperiod (16 h). © Pascal Rey
 

Our current research aims at deciphering the roles of thiol reductases in the functioning of stomata, which are leaf pores surrounded by two guard cells that have the capacity to modulate their volume as a function of environmental conditions. Stomata allow gas and water exchange at the leaf surface, and thus condition photosynthetic activity and growth.  Several thiol reductases are abundant in guard cells and the stomatal conductance as well as the leaf temperature is altered in Arabidopsis lines deficient for the expression of the genes coding these reductases. Our objective is to delineate the physiological functions of these reductases and of their partners/targets within the signaling network regulating the functioning of stomata in relation to environmental stimuli.  

Contact : Pascal REY