Archives of Microbiology

, Volume 171, Issue 3, pp 139–145

Selective transport of divalent cations by transition metal permeases: the Alcaligenes eutrophus HoxN and the Rhodococcus rhodochrous NhlF

  • Olaf Degen
  • Michihiko Kobayashi
  • Sakayu Shimizu
  • T. Eitinger
Original paper
  • 64 Downloads

Abstract

nhlF and hoxN, the genes encoding a cobalt transporter of Rhodococcus rhodochrous J1 and a nickel permease of Alcaligenes eutrophus H16, respectively, were expressed in Escherichia coli. 57Co2+ and 63Ni2+ transport of the recombinants was examined by means of a previously described physiological assay. Although the transporters are highly similar, different preferences for divalent transition metal cations were observed. HoxN was unable to transport 57Co2+, but mediated 63Ni2+ uptake. The latter activity was unaffected by a tenfold excess of other divalent cations, showing the specificity of HoxN for Ni2+. In contrast, NhlF transported both 57Co2+ and 63Ni2+ ion. NhlF-mediated 63Ni2+ uptake was markedly reduced in the presence of Co2+, while 57Co2+ uptake was only slightly lower in the presence of Ni2+. These results indicate different affinities of NhlF for Co2+ and Ni2+ and identified Co2+ ion as the preferred substrate.

Key wordsRhodococcus rhodochrous Alcaligenes eutrophus Nickel transport Cobalt transport Ion selectivity 

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Copyright information

© Springer-Verlag Berlin Heidelberg 1999

Authors and Affiliations

  • Olaf Degen
    • 1
  • Michihiko Kobayashi
    • 2
  • Sakayu Shimizu
    • 2
  • T. Eitinger
    • 1
  1. 1.Humboldt-Universität zu Berlin, Institut für Biologie/Mikrobiologie, Chausseestraße 117, D-10115 Berlin, Germany e-mail: thomas=eitinger@biologie.hu-berlin.de Tel. +49-30-2093-8103; Fax +49-30-2093-8102DE
  2. 2.Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kitashirakawa-oiwakecho, Sayko-ku, Kyoto 606-8502, JapanJP

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