Iron-sulphur cluster assembly in plants: distinct NFU proteins in mitochondria and plastids from Arabidopsis thaliana.
Recent results are in favour of a role for NFU-like proteins in Fe-S cluster biogenesis. These polypeptides share a conserved CXXC motif in their NFU domain. In the present study, we have characterized Arabidopsis thaliana NFU1-5 genes. AtNFU proteins are separated into two classes. NFU4 and NFU5 are part of the mitochondrial type, presenting a structural organization similar to Saccharomyces cerevisiae Nfu1p. These proteins complement a Delta isu1 Delta nfu1 yeast mutant and NFU4 mitochondrial localization was confirmed by green fluorescent protein fusion analysis. AtNFU1-3 represent a new class of NFU proteins, unique to plants. These polypeptides are made of two NFU domains, the second having lost its CXXC motif. AtNFU1-3 proteins are more related to Synechocystis PCC6803 NFU-like proteins and are localized to plastids when fused with the green fluorescent protein. NFU2 and/or NFU3 were detected in leaf chloroplasts by immunoblotting. NFU1 and NFU2 are functional NFU capable of restoring the growth of a Delta isu1 Delta nfu1 yeast mutant, when addressed to yeast mitochondria. Furthermore, NFU2 recombinant protein is capable of binding a labile 2Fe-2S cluster in vitro. These results demonstrate the presence of distinct NFU proteins in Arabidopsis mitochondria and plastids. Such results suggest the existence of two different Fe-S assembly machineries in plant cells.
Léon
Sébastien
S
Biochimie et Physiologie Moléculaire des Plantes, CNRS, Unité Mixte de Recherche 5004, Institut National de la Recherche Agronomique et Ecole Nationale Supérieure d'Agronomie, Université Montpellier-II, 2 place Viala, F-34060 Montpellier cedex 1, France.
Touraine
Brigitte
B
Ribot
Cécile
C
Briat
Jean-François
JF
Lobréaux
Stéphane
S
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D018076:DNA, Complementary; D007506:Iron-Sulfur Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D008969:Molecular Sequence Data; D018087:Plastids / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid
D018076:DNA, Complementary; D007506:Iron-Sulfur Proteins; D011993:Recombinant Fusion Proteins