A novel eukaryotic factor for cytosolic Fe-S cluster assembly.
Iron regulatory protein 1 (IRP1) is regulated through the assembly/disassembly of a [4Fe-4S] cluster, which interconverts IRP1 with cytosolic aconitase. A genetic screen to isolate Saccharomyces cerevisiae strains bearing mutations in genes required for the conversion of IRP1 to c-aconitase led to the identification of a previously uncharacterized, essential gene, which we call CFD1 (cytosolic Fe-S cluster deficient). CFD1 encodes a highly conserved, putative P-loop ATPase. A non-lethal mutation of CFD1 (cfd1-1) reduced c-aconitase specific activity in IRP1-transformed yeast by >90%, although IRP1 in these cells could be readily converted to c-aconitase in vitro upon incubation with iron alone. IRP1-transformed cfd1-1 yeast lacked EPR-detectable Fe-S clusters in c-aconitase, pointing to a defect in Fe-S cluster assembly. The specific activity of another cytosolic Fe-S protein, Leu1p, was also inhibited by >90% in cfd1-1 yeast, whereas activity of mitochondrial Fe-S proteins was not inhibited. Consistent with a cytosolic site of activity, Cfd1p was localized in the cytoplasm. To our knowledge, Cfd1p is the first cytoplasmic Fe-S cluster assembly factor described in eukaryotes.
Roy
Amit
A
Department of Microbiology and Immunology, University of Illinois at Chicago, Chicago, IL 60612, USA.
Solodovnikova
Natalia
N
Nicholson
Tracy
T
Antholine
William
W
Walden
William E
WE
D000154:Aconitate Hydratase / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D004578:Electron Spin Resonance Spectroscopy; D015966:Gene Expression Regulation, Fungal; D005816:Genetic Complementation Test; D006801:Humans; D035941:Iron Regulatory Protein 1 / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D007506:Iron-Sulfur Proteins / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014162:Transfection
D007506:Iron-Sulfur Proteins; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D000154:Aconitate Hydratase; D035941:Iron Regulatory Protein 1