Site-directed mutagenesis of Azotobacter vinelandii ferredoxin I: [Fe-S] cluster-driven protein rearrangement.
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.
Martín
A E
AE
Department of Molecular Biology and Biochemistry, University of California, Irvine 92717.
Burgess
B K
BK
Stout
C D
CD
Cash
V L
VL
Dean
D R
DR
Jensen
G M
GM
Stephens
P J
PJ
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
D005288:Ferredoxins; D013455:Sulfur; D007501:Iron