The bacterium Cupriavidus metallidurans is capable of reducing toxic Au(I/III)-complexes into metallic gold (Au) nano-particles, thereby mediating the (trans)formation of Au nuggets in Earth surface environments. In this study we describe a novel detoxification pathway, which prevents synergistic copper (Cu)/Au-toxicity. Gold-complexes and Cu-ions exert cooperative toxicity, because cellular uptake of Au(I/III)-complexes blocks Cu(I) export from the cytoplasm by the Cu-efflux pump CupA. Using a combination of micro-analytical and biochemical methods we show that inducible resistance to these Cu/Au mixtures is mediated by the periplasmic Cu(I)-oxidase CopA, which functions as an oxygen-consuming Au(I)-oxidase. With high Au-complex loads the enzymatic activity of CopA detoxifies the reduction pathway of Au(III)-complexes via Au(I)-intermediates to Au(0) nanoparticles in the periplasm. Thereby the concentration of highly toxic Au(I) in the cytoplasm is diminished, while allowing direct reduction of Au(III) to Au nanoparticles in the periplasm. This permits C. metallidurans to thrive in Au-rich environments and biomineralise metallic Au.

中文翻译：

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在金生物矿化的核心协同金铜解毒贪铜metallidurans †

金属利古里亚铜细菌能够将有毒的Au（I / III）络合物还原成金属金（Au）纳米粒子，从而介导地球表面环境中金块的（转化）形成。在这项研究中，我们描述了一种新型的排毒途径，可以防止协同作用的铜（Cu）/ Au毒性。金络合物和铜离子发挥协同毒性，因为细胞吸收Au（I / III）络合物会阻止Cu（I）通过Cu外排泵CupA从细胞质中输出。结合使用微观分析和生化方法，我们表明对这些Cu / Au混合物的诱导抗性是由周质Cu（I）-氧化酶CopA，起耗氧的Au（I）-氧化酶的作用。在高Au复合物负载下，CopA的酶活性解毒了Au（III）复合物通过Au（I）中间体还原为周质中Au（0）纳米粒子的还原途径。因此，降低了细胞质中高毒性Au（I）的浓度，同时允许将Au（III）直接还原为周质中的Au纳米颗粒。这使金属利尿梭菌在富含金的环境中壮成长并生物矿化金属金。