High-Level Resistance to Cobalt and Nickel but Probably No Transenvelope Efflux: Metal Resistance in the Cuban "Serratia marcescens" Strain C-1

• Jeannette Marrero ^[2] ; Georg Auling ^[3] ; Orquidea Coto ^[1] ; Dietrich H. Nies ^{[2] [4]}
  1. [1] Universidad de La Habana

     Universidad de La Habana

     Cuba

     
  2. [2] Institut für Mikrobiologie, Martin-Luther-Universität Halle-Wittenberg.Germany
  3. [3] Institut für Mikrobiologie, Universität Hannover. Germany
  4. [4] Molecular Microbiology. Halle. Germany

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• Localización: Microbial ecology, ISSN-e 1432-184X, ISSN 0095-3628, Vol. 53, Nº. 1, 2007, págs. 123-133
• Idioma: inglés
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• Resumen

  • Molecular mechanisms underlying inducible cobalt and nickel resistance of a bacterial strain isolated from a Cuban serpentine deposit were investigated. This strain C-1 was assigned to Serratia marcescens by 16S rDNA analysis and DNA/DNA hybridization. Genes involved in metal resistance were identified by transposon mutagenesis followed by selection for cobalt- and nickel-sensitive derivatives. The transposon insertion causing the highest decrease in metal resistance was located in the ncrABC determinant. The predicted NcrA product was a NreB ortholog of the major facilitator protein superfamily and central for cobalt/nickel resistance in S. marcescens strain C-1. NcrA also mediated metal resistance in Escherichia coli and caused decreased accumulation of Co(II) and Ni(II) in this heterologous host. NcrB may be a regulatory protein. NcrC was a protein of the nickel–cobalt transport (NiCoT) protein family and necessary for full metal resistance in E. coli, but only when NcrA was also present. Without NcrA, NcrC caused a slight decrease in metal resistance and mediated increased accumulation of Ni(II) and Co(II). Because the cytoplasmic metal concentration can be assumed to be the result of a flow equilibrium of uptake and efflux processes, this interplay between metal uptake system NcrC and metal efflux system NcrA may contribute to nickel and cobalt resistance in this bacterium.