title: Crystal structure of the all-ferrous [4Fe-4S]0 form of the nitrogenase iron protein from Azotobacter vinelandii.
abstract: The structure of the nitrogenase iron protein from Azotobacter vinelandii in the all-ferrous [4Fe-4S](0) form has been determined to 2.25 A resolution by using the multiwavelength anomalous diffraction (MAD) phasing technique. The structure demonstrates that major conformational changes are not necessary either in the iron protein or in the cluster to accommodate cluster reduction to the [4Fe-4S](0) oxidation state. A survey of [4Fe-4S] clusters coordinated by four cysteine ligands in proteins of known structure reveals that the [4Fe-4S] cluster of the iron protein has the largest accessible surface area, suggesting that solvent exposure may be relevant to the ability of the iron protein to exist in three oxidation states.
authors.affiliation: Biochemistry Option, California Institute of Technology, Mail Code 147-75, Pasadena, California 91125, USA.
authors.forename: P
authors.initials: P
authors.lastname: Strop
authors.forename: P M
authors.initials: PM
authors.lastname: Takahara
authors.forename: H
authors.initials: H
authors.lastname: Chiu
authors.forename: H C
authors.initials: HC
authors.lastname: Angove
authors.forename: B K
authors.initials: BK
authors.lastname: Burgess
authors.forename: D C
authors.initials: DC
authors.lastname: Rees
mesh_terms: D000577:Amides / Q000737:chemistry; D016948:Azotobacter vinelandii / Q000201:enzymology*; D018360:Crystallography, X-Ray; D005296:Ferrous Compounds / Q000737:chemistry* / Q000378:metabolism; D006860:Hydrogen Bonding; D007506:Iron-Sulfur Proteins / Q000737:chemistry* / Q000378:metabolism; D009591:Nitrogenase / Q000737:chemistry / Q000378:metabolism; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry* / Q000378:metabolism; D013455:Sulfur / Q000737:chemistry; D013499:Surface Properties
chemical_list: D000577:Amides; D005296:Ferrous Compounds; D007506:Iron-Sulfur Proteins; D013455:Sulfur; D010088:Oxidoreductases; D009591:Nitrogenase; C029130:nitrogenase reductase