The plastidial Arabidopsis thaliana NFU1 protein binds and delivers [4Fe-4S] clusters to specific client proteins

• Published in: The Journal of biological chemistry Vol. 295; no. 6; pp. 1727 - 1742
• Main Authors: Roland, Mélanie, Przybyla-Toscano, Jonathan, Vignols, Florence, Berger, Nathalie, Azam, Tamanna, Christ, Loick, Santoni, Véronique, Wu, Hui-Chen, Dhalleine, Tiphaine, Johnson, Michael K., Dubos, Christian, Couturier, Jérémy, Rouhier, Nicolas
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 07.02.2020; American Society for Biochemistry and Molecular Biology
• Subjects: Arabidopsis - metabolism; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; chloroplast; Chloroplast Proteins - metabolism; Iron-Sulfur Proteins - metabolism; iron–sulfur protein; Life Sciences; maturation; NFU; Photosystem I Protein Complex - metabolism; Plant Biology; Plastids - metabolism; protein assembly; Protein Binding; Protein Interaction Maps; sulfur; Vegetal Biology; iron–sulfur protein; Arabidopsis thaliana; maturation; chloroplast; sulfur; NFU; protein assembly; protein maturation; iron-sulfur cluster; sulfur mobilization (SUF); transfer protein; scaffold protein; protein-protein interaction; plant metabolism
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.RA119.011034

Proteins incorporating iron–sulfur (Fe-S) co-factors are required for a plethora of metabolic processes. Their maturation depends on three Fe-S cluster assembly machineries in plants, located in the cytosol, mitochondria, and chloroplasts. After de novo formation on scaffold proteins, transfer proteins load Fe-S clusters onto client proteins. Among the plastidial representatives of these transfer proteins, NFU2 and NFU3 are required for the maturation of the [4Fe-4S] clusters present in photosystem I subunits, acting upstream of the high-chlorophyll fluorescence 101 (HCF101) protein. NFU2 is also required for the maturation of the [2Fe-2S]-containing dihydroxyacid dehydratase, important for branched-chain amino acid synthesis. Here, we report that recombinant Arabidopsis thaliana NFU1 assembles one [4Fe-4S] cluster per homodimer. Performing co-immunoprecipitation experiments and assessing physical interactions of NFU1 with many [4Fe-4S]-containing plastidial proteins in binary yeast two-hybrid assays, we also gained insights into the specificity of NFU1 for the maturation of chloroplastic Fe-S proteins. Using bimolecular fluorescence complementation and in vitro Fe-S cluster transfer experiments, we confirmed interactions with two proteins involved in isoprenoid and thiamine biosynthesis, 1-hydroxy-2-methyl-2-(E)-butenyl-4-diphosphate synthase and 4-amino-5-hydroxymethyl-2-methylpyrimidine phosphate synthase, respectively. An additional interaction detected with the scaffold protein SUFD enabled us to build a model in which NFU1 receives its Fe-S cluster from the SUFBC2D scaffold complex and serves in the maturation of specific [4Fe-4S] client proteins. The identification of the NFU1 partner proteins reported here more clearly defines the role of NFU1 in Fe-S client protein maturation in Arabidopsis chloroplasts among other SUF components.