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Journal of Bacteriology, November 2004, p. 7653-7658, Vol. 186, No. 22
0021-9193/04/$08.00+0     DOI: 10.1128/JB.186.22.7653-7658.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.

The CorA Mg²⁺ Transporter Does Not Transport Fe²⁺

Krisztina M. Papp and Michael E. Maguire^*

Department of Pharmacology, Case School of Medicine, Case Western Reserve University, Cleveland, Ohio

Received 8 June 2004/ Accepted 13 August 2004

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.

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* Corresponding author. Mailing address: Department of Pharmacology, School of Medicine, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH 44106-4965. Phone: (216) 368-6186. Fax: (216) 368-3395. E-mail: mem6{at}po.cwru.edu.

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Journal of Bacteriology, November 2004, p. 7653-7658, Vol. 186, No. 22
0021-9193/04/$08.00+0     DOI: 10.1128/JB.186.22.7653-7658.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.

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