Spectroscopic and Voltammetric Characterisation of the Bacterioferritin-Associated Ferredoxin of Escherichia Coli

Biochem Biophys Res Commun. 1996 Dec 13;229(2):635-42. doi: 10.1006/bbrc.1996.1856.

Abstract

The bacterioferritin-associated ferredoxin (Bfd) of Escherichia coli is a 64-residue polypeptide encoded by the bfd gene located upstream of the gene (bfr) encoding the iron-storage haemoprotein, bacterioferritin. The Bfd sequence resembles those of the approximately 60-residue domains found in NifU proteins (required for metallocluster assembly), nitrite reductases, and Klebsiella pneumoniae nitrate reductase. These related-domains contain four well-conserved cysteine residues, which are thought to function as ligands to a [2Fe-2S] cluster. The Bfd protein was over-produced, purified, and characterised. Bfd was found to be a positively-charged monomer containing two iron atoms and two labile sulphides. Ultraviolet-visible, EPR, variable-temperature magnetic-circular dichroism and resonance Raman spectroscopies, together with cyclic voltogram measurements, revealed the presence of a [2Fe-2S]2+,+ centre (E1/2 = -254 mV) having remarkably similar properties to the Fe-S cluster of NifU. Bfd may thus be a 2Fe ferredoxin participating either in release/delivery of iron from/to bacterioferritin (or other iron complexes), or in iron-dependent regulation of bfr expression.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins*
  • Cytochrome b Group / chemistry*
  • Cytochrome b Group / genetics
  • Cytochrome b Group / isolation & purification
  • Electrochemistry
  • Escherichia coli / chemistry*
  • Ferredoxins / chemistry*
  • Ferritins / chemistry*
  • Ferritins / genetics
  • Ferritins / isolation & purification
  • Glutathione Transferase / genetics
  • Molecular Sequence Data
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / isolation & purification
  • Spectrum Analysis

Substances

  • Bacterial Proteins
  • Cytochrome b Group
  • Ferredoxins
  • Recombinant Fusion Proteins
  • Ferritins
  • bacterioferritin
  • Glutathione Transferase