Decrypting the chloroplastic [fe-s] cluster assembly machinery

Iron-Sulfur ([Fe-S]) clusters are metal cofactors of proteins involved in many fundamental metabolic pathways and cellular processes occurring in both prokaryotes and eukaryotes ( e.g. respiration, photosynthesis). [Fe-S] clusters participate in electrontransfer, substrate binding/activation, iron and sulfur storage, regulation of gene expression, and enzyme activity. The [Fe-S] cluster biogenesis machinery is composed of scaffold proteins that build the cluster de novo and of carrier proteins that transfer the [Fe-S] prosthetic groups to their target proteins (also called apoproteins). In plants three different machineries lead to [Fe-S] cluster assembly, namely the mitochondrial ISC (Iron Sulfer Cluster) system, the chloroplastic SUF (SUlFur mobilization) system and the cytosolic CIA (Cytosolic Iron-sulfur cluster Assembly) system. Our team focuses mainly on the chloroplastic SUF system and specifically on the characterization of a [Fe-S] carrier proteins named NFU2 ( NiFU-LIKE PROTEIN 2) and its potential role on the maturation of the 45 putative chloroplastic [Fe-S] cluster proteins. The [Fe-S] cluster acquisition of only 5 targets among the 45 putative chloroplastic [Fe-S] cluster proteins has already been explored. Thus, the identification of the carriers that act on the other 40 targets is still a big challenge. In order to shed new light on this process, we have initiated the global characterisation of the nfu2 mutant using proteomic (quantitative label free mass-spectrometry strategy) and metabolomic approaches. Results obtained within the frame of this work will be discussed.