title: Structure of the yeast WD40 domain protein Cia1, a component acting late in iron-sulfur protein biogenesis.
abstract: The WD40-repeat protein Cia1 is an essential, conserved member of the cytosolic iron-sulfur (Fe/S) protein assembly (CIA) machinery in eukaryotes. Here, we report the crystal structure of Saccharomyces cerevisiae Cia1 to 1.7 A resolution. The structure folds into a beta propeller with seven blades pseudo symmetrically arranged around a central axis. Structure-based sequence alignment of Cia1 proteins shows that the WD40 propeller core elements are highly conserved. Site-directed mutagenesis of amino acid residues in loop regions with high solvent accessibility identified that the conserved top surface residue R127 performs a critical function: the R127 mutant cells grew slowly and were impaired in cytosolic Fe/S protein assembly. Human Ciao1, which reportedly interacts with the Wilms' tumor suppressor, WT1, is structurally similar to yeast Cia1. We show that Ciao1 can functionally replace Cia1 and support cytosolic Fe/S protein biogenesis. Hence, our structural and biochemical studies indicate the conservation of Cia1 function in eukaryotes.
authors.affiliation: Department of Molecular Membrane Biology, Max-Planck Institute for Biophysics, Max-von-Laue Str. 3, D-60438 Frankfurt/M, Germany.
authors.forename: Vasundara
authors.initials: V
authors.lastname: Srinivasan
authors.forename: Daili J A
authors.initials: DJ
authors.lastname: Netz
authors.forename: Holger
authors.initials: H
authors.lastname: Webert
authors.forename: Judita
authors.initials: J
authors.lastname: Mascarenhas
authors.forename: Antonio J
authors.initials: AJ
authors.lastname: Pierik
authors.forename: Hartmut
authors.initials: H
authors.lastname: Michel
authors.forename: Roland
authors.initials: R
authors.lastname: Lill
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000737:chemistry* / Q000378:metabolism; D003001:Cloning, Molecular; D018360:Crystallography, X-Ray; D006801:Humans; D007506:Iron-Sulfur Proteins / Q000737:chemistry / Q000378:metabolism*; D056511:Metallochaperones; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000378:metabolism; D016415:Sequence Alignment; D013329:Structure-Activity Relationship
chemical_list: C112111:CIAO1 protein, human; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; C472823:Cia1p protein, S cerevisiae; D007506:Iron-Sulfur Proteins; D056511:Metallochaperones; D029701:Saccharomyces cerevisiae Proteins