title: Refined crystal structure of ferredoxin II from Desulfovibrio gigas at 1.7 A.
abstract: The crystal structure of ferredoxin II from Desulfovibrio gigas has been determined using phasing from anomalous scattering data at a resolution of 1.7 A and refined to an R-factor of 0.157. The molecule has an overall chain fold similar to that of the other bacterial ferredoxins of known structure. The molecule contains a single 3Fe-4S cluster with geometry indistinguishable from the 4Fe-4S clusters, and a disulfide bond near the site corresponding to the position of the second cluster of two-cluster ferredoxins. The cluster is bound by cysteine residues 8, 14 and 50. The side-chain of cysteine 11 extends away from the cluster, but could rotate to become the fourth cysteine ligand in the four-iron form of the molecule given a local adjustment of the polypeptide chain. This residue is modified, however, by what appears to be a methanethiol group. There are a total of eight NH . . . S bonds to the inorganic and cysteine sulfur atoms of the Fe-S cluster. There is an additional residue found that is not reported for the chemical sequence: according to the electron density a valine residue should be inserted after residue 55.
authors.affiliation: Department of Biological Structure, University of Washington, Seattle 98195.
authors.forename: C R
authors.initials: CR
authors.lastname: Kissinger
authors.forename: L C
authors.initials: LC
authors.lastname: Sieker
authors.forename: E T
authors.initials: ET
authors.lastname: Adman
authors.forename: L H
authors.initials: LH
authors.lastname: Jensen
mesh_terms: D000595:Amino Acid Sequence; D003460:Crystallization; D003545:Cysteine / Q000737:chemistry; D003901:Desulfovibrio / Q000032:analysis*; D005288:Ferredoxins / Q000737:chemistry* / Q000378:metabolism; D006860:Hydrogen Bonding; D007501:Iron / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D011487:Protein Conformation; D013455:Sulfur / Q000737:chemistry; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D005288:Ferredoxins; D013455:Sulfur; D007501:Iron; D003545:Cysteine