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- Title
Magnesium transport in Salmonella typhimuhum: the influence of new mutations conferring Co<sup>2+</sup> resistance on the CorA Mg<sup>2+</sup> transport system.
- Authors
Gibson, M. M.; Bagga, D. A.; Miller, C. G.; Maguire, M. E.
- Abstract
The CorA Mg2+ transport system of <em>Salmonella typhimurium</em> mediates both influx and efflux of Mg2+. Mutations at the corA locus (83.5min) confer resistance to Co2+. Using transposon mutagenesis, three additional Co2+ resistance loci (<em>corB, corC, and cord</em>) were found and mapped to 55, 15, and 3 min, respectively, on the <em>S. typhimurium</em> chromosome. No mutations corresponding to the reported corB locus at 95 min in <em>Escherichia coli</em> were obtained. The <em>corB, corC</em>, and <em>corD</em> mutations confer levels of Co2+. resistance intermediate between those of the wild-type and <em>corA</em> mutations. Isogenic straits were constructed containing combinations of transposon insertion mutations in each of the three Co2+-resistance loci to assess their influence on the CorA Mg2+ transport system. The Vmax and Km values for 28Mg2+ or for 57Co2+ and 63Ni2+ influx, analogues of Mg2+ transported by the CorA system, were changed less than twofold compared with the wild-type values, regardless of the mutation(s) present. However, while efflux of 28Mg2+ through the CorA system was decreased threefold in strains carrying one or two mutant alleles among <em>corB, corC</em>, or <em>corD</em>, efflux was completely abolished in either a <em>corA</em> or a <em>corBCD</em> strain. Thus, although the <em>corA</em> gene product is necessary and sufficient to mediate Mg2+ influx, Mg2+ efflux requires the presence of a wild-type allele of at least one of the <em>corB</em>, <em>corC</em> or ...
- Subjects
SALMONELLA typhimurium; MOBILE genetic elements; ESCHERICHIA; GENETICS; ESCHERICHIA coli
- Publication
Molecular Microbiology, 1991, Vol 5, Issue 11, p2753
- ISSN
0950-382X
- Publication type
Article
- DOI
10.1111/j.1365-2958.1991.tb01984.x