Conserved histidine residues at the ferroxidase centre of the Campylobacter jejuni Dps protein are not strictly required for metal binding and oxidation

Microbiology (Reading). 2016 Jan;162(1):156-163. doi: 10.1099/mic.0.000210. Epub 2015 Nov 9.

Abstract

Iron is an essential micronutrient for living organisms as it is involved in a broad variety of important biological processes. However, free iron inside the cell could be potentially toxic, generating hydroxyl radicals through the Fenton reaction. Dps (DNA-binding protein from starved cells) belongs to a subfamily of ferritins and can store iron atoms inside the dodecamer. The presence of a ferroxidase centre, composed of highly conserved residues, is a signature of this protein family. In this study, we analysed the role of two conserved histidine residues (H25 and H37) located at the ferroxidase centre of the Campylobacter jejuni Dps protein by replacing them with glycine residues. The C. jejuni H25G/H37G substituted variant showed reduced iron binding and ferroxidase activities in comparison with wt Dps, while DNA-binding activity remained unaffected. We also found that both CjDps wt and CjDps H25G/H37G were able to bind manganese atoms. These results indicate that the H25 and H37 residues at the ferroxidase centre of C. jejuni Dps are not strictly required for metal binding and oxidation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs
  • Amino Acid Sequence
  • Bacterial Proteins / chemistry*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Binding Sites
  • Campylobacter jejuni / chemistry
  • Campylobacter jejuni / enzymology*
  • Campylobacter jejuni / genetics
  • Ceruloplasmin / chemistry*
  • Ceruloplasmin / genetics
  • Ceruloplasmin / metabolism*
  • Conserved Sequence
  • Histidine / chemistry
  • Histidine / genetics
  • Histidine / metabolism*
  • Iron / metabolism*
  • Kinetics
  • Molecular Sequence Data
  • Oxidation-Reduction

Substances

  • Bacterial Proteins
  • Histidine
  • Iron
  • Ceruloplasmin