Gold metabolism in Cupriavidus metallidurans

Cupriavidus Metallidurans 中的金代谢

• 批准号: 413987102
• 负责人: Professor Dr. Dietrich H. Nies
• 金额: --
• 依托单位: Institutsbereich Mikrobiologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/413987102?language=en
• 关键词: Gold; metabolism; Cupriavidus; metallidurans

In the last decade our group has, in close cooperation with Frank Reith in Australia and other partners, revealed, why and how the metallophilic bacterium Cupriavidus metallidurans forms gold nanoparticles in its periplasm. Upon contact with the cell, Au(III) complexes are rapidly reduced to Au(I) species, which are imported into the cytoplasm. Here, they damage the cell and inhibit export of surplus Cu(I), leading to synergistic Au/Cu toxicity. To counteract this threat, C. metallidurans oxidizes in the periplasm Au(I) back to Au(III) using the oxidase CopA, which decreases Au uptake into the cytoplasm and allows direct reduction of Au(III) to metallic Au(0) nano-particles so that the toxic Au(I) intermediate is not formed. This grant proposal addresses open questions. First, when C. metallidurans was incubated with 50 micrometer Au(III) tetrachloride, the cells accumulated Au after 1 min in the cytoplasm. Accumulation continued and after 6 h, all of the Au was converted into an Au(I)-S species. “Hot spots” indicating formation of Au nanoparticles in the periplasm occurred from 72 h on, in parallel with transformation of the Au(I)-S species into metallic Au(0) and an Au(I)-C species, which could be Au(I)-CH3 or Au(I)-CN. Consequently, CopA not only oxidizes Au(I) back to prevent its re-import into the cytoplasm, it also frees Au(I) from a nearly covalent Au(I)-S bond to facilitate formation of the nanoparticles. But how can a cytoplasmic Au(I)-S species be transported back to the periplasm? Second, silver may also be a component of auriferous soil, with a mean content of 50 ng/g soil, comparable to that of gold at 80 ng/g. Silver induced up-regulation of cup and gig components for a copper efflux pump and products of gold induced genes without known function. A ∆cupC/AR ∆copF mutant of strain CH34 displayed decreased silver resistance. How does Ag(I) interfere with copper and gold resistance? Third, the CopC cytoplasmic metal chaperone binds Au(I). How does CopC contribute to the picture? Does it inhibit Au(I)-mediated inhibition of copper transport by CupA or is it responsible for this process? Last, C. metallidurans is not the only bacterium associated with gold grains. How does the bacterium interact with other bacteria in the golden environment?Consequently, five topics will be addressed:1. Connection between Au(I), Ag(I), Cu(I) export from the cytoplasm and glutathione.2. Active excretion of gold nanoparticles by complemented ∆gshA mutants, which cannot synthesize glutatione.3. Interaction between copper-exporting PIB1-type ATPases, Au(I), Ag(I), CupC and glutathione.4. Interaction between periplasmic Cu(I) oxidases and glutathione.5. Comparison of gold resistance and mobilization of C. metallidurans with other gold-associated bacteria.Topic 1 will be the major goal of the work, topics 2 and 3 minor goals, topics 4 and 5 back-up and test-bed experiments that may be further pursued in a second period.

在过去的十年中，我们的团队与澳大利亚的Frank Reith和其他合作伙伴密切合作，揭示了嗜金属细菌Cupriavidus metallidurans在其周质中形成金纳米颗粒的原因和方式。在与细胞接触时，Au（III）络合物迅速还原为Au（I）物质，其被输入细胞质。在这里，它们破坏细胞并抑制过剩Cu（I）的输出，导致协同的Au/Cu毒性。为了应对这一威胁，C。在一些实施方案中，金属硬聚糖使用氧化酶CopA在周质中将Au（I）氧化回Au（III），这减少了Au摄取到细胞质中，并允许将Au（III）直接还原成金属Au（0）纳米颗粒，从而不形成有毒的Au（I）中间体。这项拨款提案解决了悬而未决的问题。首先，当C. metallidurans与50微米的四氯化Au（III）一起孵育，1分钟后细胞在细胞质中积累Au。继续积累，6小时后，所有的Au转化为Au（I）-S物质。“热点”表明周质中Au纳米颗粒的形成从72小时开始发生，与Au（I）-S物质转化为金属Au（0）和Au（I）-C物质（其可以是Au（I）-CH 3或Au（I）-CN）平行。因此，CopA不仅将Au（I）氧化回以防止其重新输入细胞质，还将Au（I）从几乎共价的Au（I）-S键中释放出来以促进纳米颗粒的形成。但细胞质Au（I）-S物质如何被转运回周质呢？第二，银也可能是含金土壤的一种成分，平均含量为50纳克/克土壤，与80纳克/克的金相当。银诱导铜外排泵的cup和gig组分的上调，以及金诱导的功能未知的基因产物。菌株CH 34的Δ cupC/AR Δ copF突变体显示出降低的银抗性。Ag（I）如何干扰铜和金的电阻？第三，CopC细胞质金属伴侣结合Au（I）。CopC如何为这幅图景做出贡献？它是否抑制Au（I）介导的CupA对铜转运的抑制，或者它是否负责这一过程？最后，C.耐金属菌并不是唯一与金粒相关的细菌。在黄金环境中，细菌如何与其他细菌相互作用？因此，将讨论五个主题：1。细胞质输出的Au（I）、Ag（I）、Cu（I）与谷胱甘肽之间的联系.通过互补的不能合成谷胱甘肽的BgshA突变体主动分泌金纳米颗粒.铜输出PIB 1型ATP酶、Au（I）、Ag（I）、CupC和谷胱甘肽之间的相互作用.周质Cu（I）氧化酶和谷胱甘肽之间的相互作用。5. C.抗金性和活化性的比较。专题1将是工作的主要目标，专题2和3是次要目标，专题4和5是后备和试验台实验，可能在第二阶段进一步进行。