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Comparative and Functional Genomics
Volume 6 (2005), Issue 1-2, Pages 17-56
Research paper

Genomic Analyses of Transport Proteins in Ralstonia metallidurans

1Division of Biological Sciences, University of California at San Diego, La Jolla, CA 92093-0116, USA
2Molekulare Mikrobiologie, Institut für Mikrobiologie, Martin-Luther-Universität Halle-Wittenberg, Halle 06099, Germany

Received 14 May 2004; Revised 14 December 2004; Accepted 15 December 2004

Copyright © 2005 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Ralstonia (Wautersia, Cupriavidus) metallidurans (Rme) is better able to withstand high concentrations of heavy metals than any other well-studied organism. This fact renders it a potential agent of bioremediation as well as an ideal model organism for understanding metal resistance phenotypes. We have analysed the genome of Rme for genes encoding homologues of established and putative transport proteins; 13% of all genes in Rme encode such homologues. Nearly one-third of the transporters identified (32%) appear to function in inorganic ion transport with three-quarters of these acting on cations. Transporters specific for amino acids outnumber sugar transporters nearly 3: 1, and this fact plus the large number of uptake systems for organic acids indicates the heterotrophic preferences of these bacteria. Putative drug efflux pumps comprise 10% of the encoded transporters, but numerous efflux pumps for heavy metals, metabolites and macromolecules were also identified. The results presented should facilitate genetic manipulation and mechanistic studies of transport in this remarkable bacterium.