title: Expression in Escherichia coli and characterization of a reconstituted recombinant 7Fe ferredoxin from Desulfovibrio africanus.
abstract: Desulfovibrio africanus ferredoxin III is a monomeric protein (molecular mass of 6585 Da) that contains one [3Fe-4S]1+/0 and one [4Fe-4S]2+/1+ cluster when isolated aerobically. The amino acid sequence consists of 61 amino acids, including seven cysteine residues that are all involved in co-ordination to the clusters. In order to isolate larger quantities of D. africanus ferredoxin III, we have overexpressed it in Escherichia coli by constructing a synthetic gene based on the amino acid sequence of the native protein. The recombinant ferredoxin was expressed in E. coli as an apoprotein. We have reconstituted the holoprotein by incubating the apoprotein with excess iron and sulphide in the presence of a reducing agent. The reconstituted recombinant ferredoxin appeared to have a lower stability than that of wild-type D. africanus ferredoxin III. We have shown by low-temperature magnetic circular dichroism and EPR spectroscopy that the recombinant ferredoxin contains a [3Fe-4S]1+/0 and a [4Fe-4S]2+/1+ cluster similar to those found in native D. africanus ferredoxin III. These results indicate that the two clusters have been correctly inserted into the recombinant ferredoxin.
authors.affiliation: Centre for Metalloprotein Spectroscopy and Biology, School of Chemical Sciences, University of East Anglia, Norwich, U.K.
authors.forename: J L
authors.initials: JL
authors.lastname: Busch
authors.forename: J L
authors.initials: JL
authors.lastname: Breton
authors.forename: B M
authors.initials: BM
authors.lastname: Bartlett
authors.forename: R
authors.initials: R
authors.lastname: James
authors.forename: E C
authors.initials: EC
authors.lastname: Hatchikian
authors.forename: A J
authors.initials: AJ
authors.lastname: Thomson
mesh_terms: D000595:Amino Acid Sequence; D001059:Apoproteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D001483:Base Sequence; D002942:Circular Dichroism; D003901:Desulfovibrio / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000235:genetics; D005288:Ferredoxins / Q000737:chemistry* / Q000235:genetics* / Q000302:isolation & purification; D015870:Gene Expression; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification; D013053:Spectrophotometry
chemical_list: D001059:Apoproteins; D005288:Ferredoxins; D011994:Recombinant Proteins