The CorA Mg2+ transporter does not transport Fe2+.
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.
Papp
Krisztina M
KM
Department of Pharmacology, Case School of Medicine, Case Western Reserve University, Cleveland, OH 44106-4965, USA.
Maguire
Michael E
ME
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001693:Biological Transport, Active / Q000187:drug effects; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism*; D003470:Culture Media; D005296:Ferrous Compounds / Q000378:metabolism*; D007501:Iron / Q000378:metabolism; D008274:Magnesium / Q000378:metabolism*; D009154:Mutation; D012486:Salmonella typhimurium / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*
D001426:Bacterial Proteins; D027682:Cation Transport Proteins; C072716:CorA protein, Salmonella; D003470:Culture Media; D005296:Ferrous Compounds; D007501:Iron; D008274:Magnesium