von Rozycki Torsten, Nies Dietrich H, Saier Milton H
Division of Biological Sciences, University of California at San Diego, La Jolla, CA 92093-0116, USA.
Comp Funct Genomics. 2005;6(1-2):17-56. doi: 10.1002/cfg.454.
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.
嗜金属罗尔斯通氏菌（沃氏菌属、贪铜菌属）（Ralstonia (Wautersia, Cupriavidus) metallidurans，简称Rme）比其他任何经过深入研究的生物体都更能耐受高浓度重金属。这一特性使其成为生物修复的潜在媒介，也是理解金属抗性表型的理想模式生物。我们分析了Rme的基因组，以寻找编码已知和推测的转运蛋白同源物的基因；Rme中13%的基因编码此类同源物。已鉴定出的转运蛋白中近三分之一（32%）似乎在无机离子转运中发挥作用，其中四分之三作用于阳离子。氨基酸特异性转运蛋白的数量几乎是糖类转运蛋白的3倍，这一事实以及大量的有机酸摄取系统表明了这些细菌的异养偏好。推测的药物外排泵占编码转运蛋白的10%，但也鉴定出了许多针对重金属、代谢物和大分子的外排泵。所呈现的结果应有助于对这种非凡细菌的转运进行基因操作和机制研究。
