Iron is an essential element for plant metabolism. Coordinated at the active site of various metalloproteins, iron is involved in many enzymatic reactions such as photosynthesis, respiration, nitrogen fixation, DNA and hormone synthesis. In addition, plants have to face great differences in iron availability in the environment because of their immobility, and either starvation or excess of this element can be responsible for severe nutritional disorders.
A preliminary survey by WARDA (West Africa Rice Development Association) in 2001 suggested that as much as 60% of the low land rice area in West and Central Africa may be at risk from iron toxicity leading to yield losses varying from 12% to 100%. Previous work at Montpellier has shown that several proteasome proteins respond to iron overload and that the ferritin gene (AtFer1) induction triggered by iron can be abolished by proteasome inhibitors such as MG132. Moreover, a burst of nitric oxide occurs in the chloroplast after an iron overload.
These data suggest that ubiquitination (possibly SUMOylation) and nitrosylation of proteins are part of the iron overload signalling pathway. To identify, in the plant model Arabidopsis thaliana, genes involved in the signalling of iron toxicity we will combine modern proteomics and bioinformatics tools to classical molecular genetics approaches. For this purpose, we will use the promoter of the ferritin-encoding gene AtFer1 as the terminal target of this transduction pathway and develop two innovative and complementary proteomics approaches.
As focusing at the protein and sub-cellular levels, we will analyse S-nitrosylated proteins in the chloroplasts and ubiquitinated/SUMOylated proteins in the cytoplasm/nucleus. This combination should bring novel insights on crucial post -translational features that were largely overlooked yet. In addition, the tools we propose to develop within this frame are likely to be useful for analysing other responses in plants including crops.
Call for proposal
See other projects for this call