title: Slow formation of [3Fe-4S](1+) clusters in mutant forms of Desulfovibrio africanus ferredoxin III.
abstract: Desulfovibrio africanus ferredoxin III (Da FdIII) readily interconverts between a 7Fe and an 8Fe form with Asp-14 believed to provide a cluster ligand in the latter form. To investigate the factors important for cluster interconversion in Fe/S cluster-containing proteins we have studied two variants of Da FdIII produced by site-directed mutagenesis, Asp14Glu and Asp14His, with cluster incorporation performed in vitro. Characterisation of these proteins by UV/visible, EPR and (1)H NMR spectroscopies revealed that the formation of the stable 7Fe form of these proteins takes some time to occur. Evidence is presented which indicates the [4Fe-4S](2+) cluster is incorporated prior to the [3Fe-4S](1+) cluster.
authors.affiliation: School of Chemical Sciences, University of East Anglia, Norwich Research Park, Norwich, UK.
authors.forename: J P
authors.initials: JP
authors.lastname: Hannan
authors.forename: J L
authors.initials: JL
authors.lastname: Busch
authors.forename: R
authors.initials: R
authors.lastname: James
authors.forename: A J
authors.initials: AJ
authors.lastname: Thomson
authors.forename: G R
authors.initials: GR
authors.lastname: Moore
authors.forename: S L
authors.initials: SL
authors.lastname: Davy
mesh_terms: D019943:Amino Acid Substitution; D001224:Aspartic Acid; D003901:Desulfovibrio / Q000378:metabolism*; D004578:Electron Spin Resonance Spectroscopy; D005288:Ferredoxins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D014644:Genetic Variation; D018698:Glutamic Acid; D006639:Histidine; D007506:Iron-Sulfur Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D019906:Nuclear Magnetic Resonance, Biomolecular; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013053:Spectrophotometry
chemical_list: D005288:Ferredoxins; D007506:Iron-Sulfur Proteins; D011994:Recombinant Proteins; D001224:Aspartic Acid; D018698:Glutamic Acid; D006639:Histidine