Molecular responses of Campylobacter jejuni to cadmium stress

Abstract

Cadmium ions (Cd 2+ ) are a potent carcinogen in animals, and cadmium is a toxic metal of significant environmental and occupational importance for humans [1][2][3][4][5]. Cadmium ions are very toxic even at low concentrations, but the basis for their toxicity is not fully understood. Cadmium is not a redox-active metal and does not participate in Fenton-type reactions. Moreover, it does not bind to DNA or interact with DNA in a stable manner [1,2].Several mechanisms have been proposed to explain how bacteria and lower eukaryotes protect themselves against cadmium toxicity. These include accumulation of intracellular Zn 2+ , reduction of Cd 2+ uptake, enhanced expression of the low-molecular weight cysteine-rich protein metallothionein that sequesters cadmium, binding of cadmium ions by other heavy metal-associated proteins, and an increase in intracellular disulfide content that contributes to effective binding of cadmium [6].Disulfide reductases are responsible for the modulation of intracellular disulfide concentrations. They are essential enzymes in the antioxidant mechanisms of 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 mm cadmium chloride, and the metal ions were lethal at 1 mm 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 mm 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 mm 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.Abbreviations GSH, reduced glutathione; GSSG, oxidized glutathione; MTA, 5¢-methylthioadenosine; SAH, S-adenosylhomocysteine; TCA, tricarboxylic acid.

Regulations of essential amino acids and proteomics of bacterial endophytes Sphingomonas sp. Lk11 during cadmium uptake

“…In addition, transcriptional analyses of Caulobacter crescentus cells exposed to cadmium revealed that the principal response to this metal was protection against oxidative stress (Hu et al, ). Kaakoush et al () exposed the Campylobacter jejuni to the cadmium stress and find out up‐regulation in the detoxification proteins involved in metal detoxification cadmium. Sphingomonas sp.…”

Exposure of Staphylococcus aureus to silver(I) induces a short term protective response

“…The present results using Ag(I) ions are interesting since elongation factors are required for extending the polypeptide chain in protein biosynthesis which is essential for microbial growth and development (Berisio et al 2010), and suggests that additional protein biosynthesis occurs in response to metal ion exposure (Kaakoush et al 2008).…”

“…Mol Wt (kDa) Proteomic analysis revealed an increase in expression of a range of proteins following exposure of S. aureus cells to Ag(I) ions however a number of these proteins had declined in expression by 4 h. At the 1 h time point, there was an increase in the expression of elongation factors Ts, Tu and G by 4.1-, 2.3-and 1.3-fold, respectively, but these subsequently decreased in relative expression by 4 h. Kaakoush et al (2008) also found that the elongation factors Tu and G of Campylobacter jejuni were upregulated as a result of exposure to Cd(II) ions. The present results using Ag(I) ions are interesting since elongation factors are required for extending the polypeptide chain in protein biosynthesis which is essential for microbial growth and development (Berisio et al 2010), and suggests that additional protein biosynthesis occurs in response to metal ion exposure (Kaakoush et al 2008).…”

Use of In Vivo-Induced Antigen Technology to Identify In Vivo-Expressed Genes of Campylobacter jejuni During Human Infection

“…These results indicate that the fraction of outer membrane localization of Ef-Tu was increased. The altered outer membrane protein suggests that Ef-Tu is possibly involved in the pathogenesis of C. jejuni [12,18]. The gene flhF encodes the flagellar biosynthesis regulator FlhF, which is a putative GTPase that is necessary for the development of the flagellar organelles in polarly flagellated bacteria [1].…”