0000000001045894
AUTHOR
Emmanuel Koen
showing 10 related works from this author
S-nitrosylation: An emerging post-translational protein modification in plants
2011
International audience; Increasing evidences support the assumption that nitric oxide (NO) acts as a physiological mediator in plants. Understanding its pleiotropic effects requires a deep analysis of the molecular mechanisms underlying its mode of action. In the recent years, efforts have been made in the identification of plant proteins modified by NO at the post-translational level, notably by S-nitrosylation. This reversible process involves the formation of a covalent bond between NO and reactive cysteine residues. This research has now born fruits and numerous proteins regulated by S-nitrosylation have been identified and characterized. This review describes the basic principle of S-n…
Post-Translational Modifications of Nuclear Proteins in the Response of Plant Cells to Abiotic Stresses
2011
For a long time, in plant cells as in animal cells, the nucleus was only considered as the organelle in which fundamental mechanisms such as replication and transcription occurred. While strong efforts were deployed in order to identify important families of transcription factors such as MYB, WRKY or TGA families (Dubos et al., 2010; Rushton et al., 2010), a few attention was devoted to our lack of knowledge about their regulation in regard to the physiological conditions of the plant cells. Whereas the major importance of posttranslational modification of proteins is well established for several decades regarding cytosolic proteins, the last years have been characterized by the discovery t…
Le monoxyde d’azote
2013
Le monoxyde d’azote (NO) est un mediateur physiologique associe a divers processus chez les animaux, dont l’immunite. Des travaux conduits recemment montrent que les plantes, confrontees a l’attaque d’agents pathogenes, produisent egalement du NO. Le NO est donc un acteur des voies de signalisation cellulaire activees en reponse a la reconnaissance par les plantes d’agresseurs exterieurs. L’etude des molecules cibles du NO et, plus particulierement, la caracterisation de proteines S-nitrosylees, a permis d’avoir un premier apercu des mecanismes fins inherents a ses fonctions. Le NO serait ainsi implique dans l’activation ainsi que dans la desensibilisation des voies de signalisation mobilis…
Arabidopsis thaliana nicotianamine synthase 4 is required for proper response to iron deficiency and to cadmium exposure.
2013
International audience; The nicotianamine synthase (NAS) enzymes catalyze the formation of nicotianamine (NA), a non-proteinogenic amino acid involved in iron homeostasis. We undertook the functional characterization of AtNAS4, the fourth member of the Arabidopsis thaliana NAS gene family. A mutant carrying a T-DNA insertion in AtNAS4 (atnas4), as well as lines overexpressing AtNAS4 both in the atnas4 and the wild-type genetic backgrounds, were used to decipher the role of AtNAS4 in NA synthesis, iron homeostasis and the plant response to iron deficiency or cadmium supply. We showed that AtNAS4 is an important source for NA. Whereas atnas4 had normal growth in iron-sufficient medium, it dis…
Nitric oxide production mediates oligogalacturonide-triggered immunity and resistance to Botrytis cinerea in Arabidopsis thaliana
2012
Nitric oxide (NO) regulates a wide range of plant processes from development to environmental adaptation. In this study, we investigated the production and/or function of NO in Arabidopsis thaliana leaf discs and plants elicited by oligogalacturonides (OGs) and challenged with Botrytis cinerea. We provided evidence that OGs triggered a fast and long lasting NO production which was Ca(2+) dependent and involved nitrate reductase (NR). Accordingly, OGs triggered an increase of both NR activity and transcript accumulation. NO production was also sensitive to the mammalian NO synthase inhibitor L-NAME. Intriguingly, we showed that L-NAME affected NO production by interfering with NR activity, t…
Protein S-nitrosylation: What's going on in plants?
2012
International audience; Nitric oxide (NO) is now recognized as a key regulator of plant physiological processes. Understanding the mechanisms by which NO exerts its biological functions has been the subject of extensive research. Several components of the signaling pathways relaying NO effects in plants, including second messengers, protein kinases, phytohormones, and target genes, have been characterized. In addition, there is now compelling experimental evidence that NO partly operates through posttranslational modification of proteins, notably via S-nitrosylation and tyrosine nitration. Recently, proteome-wide scale analyses led to the identification of numerous protein candidates for S-…
Nitric oxide and glutathione impact the expression of iron uptake- and iron transport-related genes as well as the content of metals in A. thaliana p…
2012
International audience; Mounting evidence indicate that nitric oxide (NO) acts as a signaling molecule mediating iron deficiency responses through the upregulation of the expression of iron uptake-related genes. Accordingly, NO donors such as nitrosoglutathione (GSNO) were reported to improve the fitness of plants grown under iron deficiency. Here, we showed that glutathione, a by-product of GSNO, triggered the upregulation of the expression of iron uptake- and transport-related gene and an increase of iron concentration in Arabidopsis thaliana seedlings facing iron deficiency. Furthermore, we provided evidence that under iron deficiency, NO released by GSNO did not improve the root iron co…
β-Aminobutyric Acid (BABA)-Induced Resistance in Arabidopsis thaliana: Link with Iron Homeostasis
2014
International audience; Bêta-Aminobutyric acid (BABA) is a nonprotein amino acid inducing resistance in many different plant species against a wide range of abiotic and biotic stresses. Nevertheless, how BABA primes plant natural defense reactions remains poorly understood. Based on its structure, we hypothesized and confirmed that BABA is able to chelate iron (Fe) in vitro. In vivo, we showed that it led to a transient Fe deficiency response in Arabidopsis thaliana plants exemplified by a reduction of ferritin accumulation and disturbances in the expression of genes related to Fe homeostasis. This response was not correlated to changes in Fe concentrations, suggesting that BABA affects the…
The plant resistance inducer β-aminobutyric acid (BABA) induces an iron deficiency response in A. thaliana
2012
β-aminobutyric acid (BABA) is a well-known plant resistance inducer. However, the molecular mechanisms underlying its effects are poorly understood. In the present study, we investigated whether BABA could act through the modification of iron homeostasis in Arabidopsis thaliana. Supporting this assumption, we obtained first evidences that BABA chelates iron with high affinity. We showed that pre-treatment of plants with BABA induced a drastic but transient iron deficiency response. Quantification of iron indicated that this response is related to the perturbation of iron distribution/availability rather than a reduction of iron assimilation. Finally, we provided evidence that the iron defic…
The role of NtRBOHD in regulation of response to cryptogein in tobacco cells
2014
International audience