Cadmium ions are a potent carcinogen in animals, and cadmium is a toxic metal of significant environmental importance for humans. Response curves were used to investigate the effects of cadmium chloride on the growth of Camplyobacter jejuni. In vitro, the bacterium showed reduced growth in the presence of 0.1 m m cadmium chloride, and the metal ions were lethal at 1 m m concentration. Two-dimensional gel electrophoresis combined with tandem mass spectrometry analysis enabled identification of 67 proteins differentially expressed in cells grown without and with 0.1 m m cadmium chloride. Cellular processes and pathways regulated under cadmium stress included fatty acid biosynthesis, protein biosynthesis, chemotaxis and mobility, the tricarboxylic acid cycle, protein modification, redox processes and the heat-shock response. Disulfide reductases and their substrates play many roles in cellular processes, including protection against reactive oxygen species and detoxification of xenobiotics, such as cadmium. The effects of cadmium on thioredoxin reductase and disulfide reductases using glutathione as a substrate were studied in bacterial lysates by spectrophotometry and nuclear magnetic resonance spectroscopy, respectively. The presence of 0.1 m m cadmium ions modulated the activities of both enzymes. The interactions of cadmium ions with oxidized glutathione and reduced glutathione were investigated using nuclear magnetic resonance spectroscopy. The data suggested that, unlike other organisms, C. jejuni downregulates thioredoxin reductase and upregulates other disulfide reductases involved in metal detoxification in the presence of cadmium.
展开▼
机译：镉离子是动物中的强致癌物，镉是对人类具有重要环境意义的有毒金属。响应曲线用于研究氯化镉对空肠弯曲杆菌生长的影响。在体外，该细菌在0.1 m m氯化镉的存在下显示出减少的生长，并且金属离子在1 m m的浓度下具有致死性。二维凝胶电泳与串联质谱分析相结合，能够鉴定在没有和有0.1 m m氯化镉的情况下生长的细胞中差异表达的67种蛋白质。在镉胁迫下调节的细胞过程和途径包括脂肪酸生物合成，蛋白质生物合成，趋化性和迁移性，三羧酸循环，蛋白质修饰，氧化还原过程和热激反应。二硫键还原酶及其底物在细胞过程中扮演着许多角色，包括针对活性氧的保护以及诸如镉等异生物的解毒。分别通过分光光度法和核磁共振波谱研究了以谷胱甘肽为底物的镉对硫氧还蛋白还原酶和二硫键还原酶的影响。 0.1 m m镉离子的存在调节了这两种酶的活性。利用核磁共振波谱研究了镉离子与氧化型谷胱甘肽和还原型谷胱甘肽的相互作用。数据表明，与其他生物不同，空肠弯曲杆菌下调硫氧还蛋白还原酶，并上调参与镉存在下金属解毒的其他二硫键还原酶。
展开▼
