Zammit Carla M, Weiland Florian, Brugger Joël, Wade Benjamin, Winderbaum Lyron Juan, Nies Dietrich H, Southam Gordon, Hoffmann Peter, Reith Frank
University of Queensland, Earth Sciences, St. Lucia, Brisbane, Queensland 4072, Australia.
Adelaide Proteomics Centre, School of Molecular and Biomedical Science, University of Adelaide, Adelaide 5005, Australia and Institute for Photonics and Advanced Sensing, University of Adelaide, Adelaide 5005, Australia.
Metallomics. 2016 Nov 9;8(11):1204-1216. doi: 10.1039/c6mt00142d.
The metal-resistant β-proteobacterium Cupriavidus metallidurans drives gold (Au) biomineralisation and the (trans)formation of Au nuggets largely via unknown biochemical processes, ultimately leading to the reductive precipitation of mobile, toxic Au(i/iii)-complexes. In this study proteomic responses of C. metallidurans CH34 to mobile, toxic Au(iii)-chloride are investigated. Cells were grown in the presence of 10 and 50 μM Au(iii)-chloride, 50 μM Cu(ii)-chloride and without additional metals. Differentially expressed proteins were detected by difference gel electrophoresis and identified by liquid chromatography coupled mass spectrometry. Proteins that were more abundant in the presence of Au(iii)-chloride are involved in a range of important cellular functions, e.g., metabolic activities, transcriptional regulation, efflux and metal transport. To identify Au-binding proteins, protein extracts were separated by native 2D gel electrophoresis and Au in protein spots was detected by laser absorption inductively coupled plasma mass spectrometry. A chaperon protein commonly understood to bind copper (Cu), CupC, was identified and shown to bind Au. This indicates that it forms part of a multi-metal detoxification system and suggests that similar/shared detoxification pathways for Au and Cu exist. Overall, this means that C. metallidurans CH34 is able to mollify the toxic effects of cytoplasmic Au(iii) by sequestering this Au-species. This effect may in the future be used to develop CupC-based biosensing capabilities for the in-field detection of Au in exploration samples.
耐金属β-变形菌金属贪铜菌主要通过未知的生化过程驱动金（Au）的生物矿化以及金块的（转）形成，最终导致可移动的有毒Au（i/iii）络合物的还原沉淀。在本研究中，对金属贪铜菌CH34对可移动的有毒Au（iii）-氯化物的蛋白质组学反应进行了研究。细胞在含有10和50μM Au（iii）-氯化物、50μM Cu（ii）-氯化物以及无额外金属的条件下生长。通过差异凝胶电泳检测差异表达的蛋白质，并通过液相色谱-质谱联用进行鉴定。在Au（iii）-氯化物存在下含量更高的蛋白质参与了一系列重要的细胞功能，例如代谢活动、转录调控、外排和金属转运。为了鉴定Au结合蛋白，蛋白质提取物通过天然二维凝胶电泳进行分离，并通过激光吸收电感耦合等离子体质谱法检测蛋白质斑点中的Au。一种通常被认为结合铜（Cu）的伴侣蛋白CupC被鉴定出来并显示能结合Au。这表明它构成了多金属解毒系统的一部分，并表明存在针对Au和Cu的相似/共享解毒途径。总体而言，这意味着金属贪铜菌CH34能够通过螯合这种Au物种来减轻细胞质中Au（iii）的毒性作用。这种效应未来可能被用于开发基于CupC的生物传感能力，用于现场检测勘探样品中的Au。
