The CorA Mg2+ transporter does not transport Fe2+

J Bacteriol. 2004 Nov;186(22):7653-8. doi: 10.1128/JB.186.22.7653-7658.2004.

Abstract

corA encodes the constitutively expressed primary Mg2+ uptake system of most eubacteria and many archaea. Recently, a mutation in corA was reported to make Salmonella enterica serovar Typhimurium markedly resistant to Fe2+-mediated toxicity. Mechanistically, this was hypothesized to be from an ability of CorA to mediate the influx of Fe2+. Consequently, we directly examined Fe2+ transport and toxicity in wild-type versus corA cells. As determined by direct transport assay, CorA cannot transport Fe2+ and Fe2+ does not potently inhibit CorA transport of 63Ni2+. Mg2+ can, relatively weakly, inhibit Fe2+ uptake, but inhibition is not dependent on the presence of a functional corA allele. Although excess Fe2+ was slightly toxic to S. enterica serovar Typhimurium, we were unable to elicit a significant differential sensitivity in a wild-type versus a corA strain. We conclude that CorA does not transport Fe2+ and that the relationship, if any, between iron toxicity and corA is indirect.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Biological Transport, Active / drug effects
  • Cation Transport Proteins / genetics
  • Cation Transport Proteins / metabolism*
  • Culture Media
  • Ferrous Compounds / metabolism*
  • Iron / metabolism
  • Magnesium / metabolism*
  • Mutation
  • Salmonella typhimurium / genetics
  • Salmonella typhimurium / growth & development
  • Salmonella typhimurium / metabolism*

Substances

  • Bacterial Proteins
  • Cation Transport Proteins
  • CorA protein, Salmonella
  • Culture Media
  • Ferrous Compounds
  • Iron
  • Magnesium