title: Site-directed mutagenesis of Azotobacter vinelandii ferredoxin I: [Fe-S] cluster-driven protein rearrangement.
abstract: Azotobacter vinelandii ferredoxin I is a small protein that contains one [4Fe-4S] cluster and one [3Fe-4S] cluster. Recently the x-ray crystal structure has been redetermined and the fdxA gene, which encodes the protein, has been cloned and sequenced. Here we report the site-directed mutation of Cys-20, which is a ligand of the [4Fe-4S] cluster in the native protein, to alanine and the characterization of the protein product by x-ray crystallographic and spectroscopic methods. The data show that the mutant protein again contains one [4Fe-4S] cluster and one [3Fe-4S] cluster. The new [4Fe-4S] cluster obtains its fourth ligand from Cys-24, a free cysteine in the native structure. The formation of this [4Fe-4S] cluster drives rearrangement of the protein structure.
authors.affiliation: Department of Molecular Biology and Biochemistry, University of California, Irvine 92717.
authors.forename: A E
authors.initials: AE
authors.lastname: Martín
authors.forename: B K
authors.initials: BK
authors.lastname: Burgess
authors.forename: C D
authors.initials: CD
authors.lastname: Stout
authors.forename: V L
authors.initials: VL
authors.lastname: Cash
authors.forename: D R
authors.initials: DR
authors.lastname: Dean
authors.forename: G M
authors.initials: GM
authors.lastname: Jensen
authors.forename: P J
authors.initials: PJ
authors.lastname: Stephens
mesh_terms: D001395:Azotobacter / Q000235:genetics* / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D005288:Ferredoxins / Q000235:genetics*; D005798:Genes, Bacterial; D007501:Iron / Q000032:analysis; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D009586:Nitrogen Fixation / Q000235:genetics; D011487:Protein Conformation; D013053:Spectrophotometry; D013455:Sulfur / Q000032:analysis; D014961:X-Ray Diffraction
chemical_list: D005288:Ferredoxins; D013455:Sulfur; D007501:Iron