Team leader: Mélanie Morel-Rouhier
The ’stress response and redox regulation’ team is located on the campus of the Faculté des Sciences & Technologies in Vandoeuvre-lès-Nancy. In January 2025, the team comprised 27 persons: 10 professors or assistant-professors (including two members of the Institut Universitaire de France), 1 research director, 2 engineers, 2 technicians, 2 research associates (postdocs), 7 PhD students, and 2 engineers under contract. Our team has longstanding and well-established connections with the following labs: Prof. Claude Didierjean (Univ. Lorraine), Dr. Stéphane Lemaire (Sorbonne Univ. France), Dr Eric Record (Aix-Marseille Université), Dr. Anna Moseler (Bonn, Germany), Prof. Claire Remacle (Liege, Belgium), Prof. Olivier Keech (Umeå, Sweden).
Our research team has the global objective of understanding how photosynthetic organisms (using in particular the model tree Populus trichocarpa) and fungi (using in particular the white rot fungus Phanerochaete chrysosporium) cope with and adapt to environmental constraints focusing on redox homeostasis and signaling. We are performing structure-function studies of several key protein families involved in the control of post-translational modifications (e.g. thioredoxins (TRX), glutaredoxins (GRX), sulfurtransferases (STR)), in the maturation of iron-sulfur proteins, in stress response and trafficking of specialized metabolites (glutathione transferases (GST), defense proteins (rust induced secreted protein)). More detailed information about the projects and scientists involved are summarized below.
SULTRAF: Roles of sulfurtransferases and cysteine desulfurases in sulfur trafficking in plants – relationship with TRX and GRX systems
Scientists involved: J. Couturier, N. Rouhier, Z. Liu (PhD), N. Simon (CDD IE)
As a major sulfur donor molecule, cysteine is a key metabolite involved in the biosynthesis of many sulfur-containing cofactors or biomolecules (Fe-S cluster, biotin, thiamine, lipoic acid, molybdopterin and thionucleosides). The first hallmark step of sulfur mobilization is the formation of persulfides on a reactive catalytic cysteine of cysteine desulfurases (CDs) upon cysteine desulfuration. The next steps for sulfur trafficking and delivery involve additional carrier proteins, belonging notably to the sulfurtransferase (STR) family, which catalyze trans-persulfidation reactions by forming themselves persulfides. Many STRs also catalyze directly the desulfuration of small substrates such as thiosulfate or 3-mercaptopyruvate. In this context, the TRX and glutathione/GRX reducing systems may serve as sulfur acceptors, leading to the release of H2S or to the formation of small persulfidated thiol containing molecules (cysteine or glutathione persulfide) thus contributing to sulfur signaling/trafficking pathways. The involvement of TRX and GRX is currently examined in detail as it might clearly modulate the overall process and/or provide the required specificity to disseminate the signal from a single persulfide-generating enzyme to specific target proteins acting in this case as secondary carriers. Furthermore, we exploit and combine the biochemical properties of some STRs and a redox sensitive version of GFP (roGFP2) to generate biosensors specific to various sulfur compounds. We hope thus to develop new tools for studying the cellular dynamics of sulfur metabolism and some of the underlying molecular mechanisms in various model organisms.
METOX: Identifying new metal- or redox-regulated functions in plants
Scientists involved: L. de Bont, M. Pottier, T. Dhalleine, N. Rouhier, J. Couturier, B. Pêtre
Within this project, we aim at characterizing proteins of unknown function possessing one or several conserved CXXC motifs which are particularly suited for disulfide bond formation and for the coordination of metals. This includes GRX or TRX-like proteins selected from in silico genome analyses. We are performing a thorough biochemical and structural characterization of the corresponding recombinant proteins, before deciphering the biological roles of the most promising candidates using genetic approaches. We anticipate to (i) unravel new cellular processes or signaling pathways in poplar/plants which are controlled by redox reactions i.e., assisted by thiol-disulfide exchanges or by metalloproteins and (ii) understand how the functions of these proteins are controlled at the cellular level and are intricated with other GRX and TRX members known so far.
FES: Molecular analysis of Fe-S cluster synthesis, insertion and transfer in organelles
Scientists involved: N. Rouhier, J. Couturier, A. Terenzi (post-doctoral researcher), Y. Aoudache (PhD), B. Das Neves (PhD), S. Inturri (PhD), A. Kairis (PhD)
The general objective here is to understand the functioning of the iron-sulfur (Fe-S) cluster assembly machineries in chloroplasts and mitochondria and more precisely the molecular mechanisms controlling both the synthesis made on scaffold proteins and the trafficking of these preformed Fe-S clusters to final acceptors using plant and microalgae as models. We extended our research interest to the functional characterization of the protein families assumed to participate in the transfer of these Fe-S clusters. We combine genetics and physiology, molecular and structural biology and biochemistry approaches to perform the functional analysis of the protein families (NFS, GRX, BOLA, NFUs, SUFA/ISCAs, IBA57s, HCF101/INDH). In particular, we aim at determining which type(s) of Fe-S clusters these proteins assemble, whether they have specific interaction partners and what are the physiological and metabolic consequences of deleting these genes for the development and physiology of these photosynthetic organisms. Particular emphasis is given to the maturation of the photosynthetic and respiratory electron transfer complexes and of enzymes of the dark fermentation, in particular Fe-Fe hydrogenases, in Chlamydomonas reinhardtii.
GLUTANAC: Biochemical and structural characterization of Glutathione Transferases with fished Natural Compounds
Scientists involved: A. Hecker, M. Morel-Rouhier, E. Gelhaye, N. Rouhier, J.M. Girardet, R. Bchini, S. Rochoux (PhD), M. Vilora (CDD IE).
Until recently, most of the studies concerning metabolite modification via glutathione transferases (GSTs) have focused on their glutathionylation activity. However, several GST classes possess a cysteinyl residue in their catalytic site (Cys-GSTs) conferring them the ability to catalyze the reverse reaction, i.e. the removal of glutathione from a number of structurally different molecules. Although they are present in all kingdoms, the physiological functions of these enzymes remain often elusive. This project aims at understanding the role of these deglutathionylating enzymes by identifying the physiological substrates of both poplar and fungal isoforms using a strategy of ligand fishing in which these GSTs are used as baits (affinity chromatography, competition between fluorescent probes and ligands for binding onto the proteins). We are not only focusing on the previously characterized Cys-GSTs (omega and lambda GSTs as well as glutathionyl hydroquinone reductases) but also on less explored or newly identified GST families to characterize the nature (ligandin vs catalytic transformation) and the strength of the interactions, such as the structure of GST/ligand complexes. These aspects will provide invaluable information necessary for understanding the molecular and physiological functions of deglutathionylating GSTs. Overall, we expect to decipher new intermediary steps of metabolic pathways requiring glutathione-conjugating or transport activities.
LifAttack: Fungal resistance to toxic environment: towards new eco-friendly strategies to limit fungal attacks on plants and wood
Scientists involved: M. Morel-Rouhier, R. Sormani, S. Darnet, E. Gelhaye, C. Blanco-Nouche (post-doctoral researcher), C. Vandekerkhove (PhD)
Fungi are amazing organisms able to resist and rapidly adapt to hostile environments. This could have dramatic consequences for crop production or wood preservation. Since the adaptive capacity of a population is intimately correlated with the selective pressure exerted by its local niche, this project aims at delineating the molecular mechanisms explaining the sensitivity/resistance phenotypes of fungi in presence of various natural plant extracts including wood. We are focusing the analysis on the detoxification systems and sterol metabolism by coupling global non a priori approaches (transcriptomic analyses) to the functional characterization of proteins of interest in fungal models such as yeasts, ligninolytic fungi and ophiostomatalean fungi that are associated with bark beetles.
Since several years, we have developed a ” Functional Reverse Chemical Ecology” approach, which consists in correlating the antifungal properties of extracts from different wood species to their physical interaction patterns with Glutathione Transferases. This approach has made it possible to identify molecules of interest with antifungal properties and also to better understand and model the natural sustainability of tree species.
Globally the results of this axis will help understanding fungal physiology, evolutionary history and adaptation, knowledge that is required for developing new eco-friendly strategies to limit fungal attacks on crops, trees and wood material.
Poprust: Molecular analysis of the poplar-rust interaction
Scientists involved: B. Petre, A. Hecker, N. Rouhier in coll. with members from other IAM teams (transverse project)
Plants undergo bio-attacks by pathogens such as fungi. How do plants cope with biotic stress at the cellular and molecular level is a key question in plant biology. Our projects focus on the molecular physiology of plant response to biotic stress, with a specific focus on the functional relation and co-evolution of secreted peptides and immune receptors. We mostly use the model interaction between poplar and the poplar leaf rust pathogen Melampsora larici-populina, as well as functional genomics, protein biochemistry, and reverse genetic approaches in heterologous systems.
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