Determining the role of Fe-chaperone Mt080 in iron distribution in Medicago truncatula root nodules

Iron delivery to target proteins is not through diffusion (free iron is toxic) but through protein-protein interactions with proteins known as iron-chaperones. While iron-chaperones have been studied in mammals, no orthologue is known in plants. Evidence from our lab has provided the identity of one candidate plant Fe-chaperone: Mt080. This protein has the iron-binding domain of mammalian iron-chaperones, interacts with iron transporter NRAMP1, the main iron importer for Medicago truncatula root nodule cells, and its mutation results in reduced nitrogenase activity (an enzyme with 38 iron atoms). We propose to use ID21 to determine how iron distribution is affected by Mt080 mutation, supporting its role as iron-chaperone. Moreover, we would like to address how the cells accommodate for this altered iron delivery pathway by determining iron speciation changes in the mutant lines, using XANES. All this information will be used to finalize a publication on the biological role of Mt080.