Department of Plant and Microbial Biology, University of Zürich, Zürich, Switzerland.
Environ Microbiol Rep. 2020 Apr;12(2):241-249. doi: 10.1111/1758-2229.12828. Epub 2020 Feb 26.
Copper is an essential element but in excess is highly toxic and therefore cytoplasmic levels must be tightly controlled. Member of the genus Burkholderia are highly resistant to various heavy metals and are often isolated from acidic soils where copper bioavailability is high. In this study, we employed transposon sequencing (Tn-Seq) to identify copper resistance genes in Burkholderia cenocepacia H111. We identified a copper efflux system that shares similarities with the plasmid-based copper detoxification systems found in Escherichia coli and Pseudomonas syringae. We also found that several of the identified resistance determinants are involved in maintaining the integrity of the cell envelope, suggesting that proteins located in the outer membrane and periplasmic space are particularly sensitive to copper stress. Given that several of the resistance genes are required for the repair and turnover of misfolded proteins, we suggest that copper toxicity is caused by protein damage rather than by oxidative stress.
铜是一种必需元素，但过量的铜具有高度毒性，因此细胞质内的铜水平必须受到严格控制。伯克霍尔德氏菌属的成员对各种重金属具有高度抗性，通常从铜生物利用度高的酸性土壤中分离出来。在这项研究中，我们采用转座子测序（Tn-Seq）技术来鉴定伯克霍尔德氏菌中铜抗性基因。我们发现了一个铜外排系统，该系统与大肠杆菌和丁香假单胞菌中发现的基于质粒的铜解毒系统具有相似性。我们还发现，鉴定出的几个抗性决定因素参与维持细胞包膜的完整性，这表明位于外膜和周质空间的蛋白质对铜胁迫特别敏感。鉴于几个抗性基因对于错误折叠蛋白质的修复和周转是必需的，我们认为铜毒性是由蛋白质损伤引起的，而不是由氧化应激引起的。
