Project description:Cupriavidus metallidurans CH34 is a metal resistant beta-proteobacterium. The genome of this bacterium contain many genes involved in heavy metal resistance. Gene expression of C. metallidurans was studied after the addition of of Zn(II), Cd(II), Cu(II), Ni(II), Pb(II), Hg(II) or Co(II). Keywords: Heavy metal stress response
2007-03-16 | GSE7272 | GEO
Project description:The dissemination of antibiotic resistance genes and heavy metal resistance genes along the sewage pipe under Cu and Zn stress
Project description:Background: The high number of heavy metal resistance genes in the soil bacterium Cupriavidus metallidurans CH34 makes it an interesting model organism to study microbial responses to heavy metals. Results: In this study the transcriptional response of this bacterium was measured after challenging it to a wide range of sub-lethal concentrations of various essential or toxic metals. Considering the global transcriptional responses for each challenge as well as by identifying the overlap in upregulated genes between different metal responses, the sixteen metals could be clustered in three different groups. Additionally, next to the assessment of the transcriptional response of already known metal resistance genes, new metal response gene clusters were identified. The majority of the metal response loci showed similar expression profiles when cells were exposed to different metals, suggesting complex cross-talk at transcriptional level between the different metal responses. The highly redundant nature of these metal resistant regions – illustrated by the large number of paralogous genes – combined with the phylogenetic distribution of these metal response regions within evolutionary related and other metal resistant bacteria, provides important insights on the recent evolution of this naturally soil dwelling bacterium towards a highly metal-resistant strain found in harsh and anthropogenic environments. Conclusions: The metal-resistant soil bacterium Cupriavidus metallidurans CH34 displays myriads of gene expression patterns when exposed to a wide range of heavy metals at non-lethal concentrations. The interplay between the different gene expression clusters points towards a complex cross-regulated regulatory network governing heavy metal resistance in C. metallidurans CH34. Keywords: Cupriavidus metallidurans CH34, transcriptional regulation, heavy metal resistance Two-condition experiments. Comparing samples after induction with heavy metals versus non-induced samples. Biological duplicate or triplicate. Each array contains 3 or 4 technical replicates.
Project description:Background: The high number of heavy metal resistance genes in the soil bacterium Cupriavidus metallidurans CH34 makes it an interesting model organism to study microbial responses to heavy metals. Results: In this study the transcriptional response of this bacterium was measured after challenging it to a wide range of sub-lethal concentrations of various essential or toxic metals. Considering the global transcriptional responses for each challenge as well as by identifying the overlap in upregulated genes between different metal responses, the sixteen metals could be clustered in three different groups. Additionally, next to the assessment of the transcriptional response of already known metal resistance genes, new metal response gene clusters were identified. The majority of the metal response loci showed similar expression profiles when cells were exposed to different metals, suggesting complex cross-talk at transcriptional level between the different metal responses. The highly redundant nature of these metal resistant regions – illustrated by the large number of paralogous genes – combined with the phylogenetic distribution of these metal response regions within evolutionary related and other metal resistant bacteria, provides important insights on the recent evolution of this naturally soil dwelling bacterium towards a highly metal-resistant strain found in harsh and anthropogenic environments. Conclusions: The metal-resistant soil bacterium Cupriavidus metallidurans CH34 displays myriads of gene expression patterns when exposed to a wide range of heavy metals at non-lethal concentrations. The interplay between the different gene expression clusters points towards a complex cross-regulated regulatory network governing heavy metal resistance in C. metallidurans CH34. Keywords: Cupriavidus metallidurans CH34, transcriptional regulation, heavy metal resistance
Project description:MAP kinases are integral to the mechanisms by which cells respond to a wide variety of environmental stresses. In Caenorhabditis elegans, the KGB-1 JNK signaling pathway regulates the response to heavy metal stress. The deletion mutants of this cascade show hypersensitivity to heavy metals like copper or cadmium. However, factors that function downstream of KGB-1 pathway are not well characterized. To understand how the KGB-1 pathway modulates gene activity and to define the physiological processes in which the heavy metal stress response may be involved, we used microarray to examine gene expression changes in wild-type and kgb-1 mutant animals subjected to heavy metal stress.
Project description:Cupriavidus metallidurans CH34 is a metal resistant beta-proteobacterium. The genome of this bacterium contain many genes involved in heavy metal resistance. Gene expression of C. metallidurans was studied after the addition of of Zn(II), Cd(II), Cu(II), Ni(II), Pb(II), Hg(II) or Co(II). Keywords: Heavy metal stress response Cultures of C. metallidurans CH34 were grown at 30°C until OD reached 0.6 (mid- exponential phase cultures). Heavy metals (0.8 mM of Zn(II), 0.5 mM of Cd(II), 0.1 mM of Cu(II), 0.6 mM of Ni(II), 0.4 mM of Pb(II), 5 uM of Hg(II) and 0.5 mM of Co(II)) were added to the culture for 30 minutes induction time. Total RNA was extracted, reverse-transcribed and labeled with Cy3-dCTP for the control (without metal) and with Cy5-dCTP for each conditions (challenged with one metal). Labeled cDNA were (control and one condition) added to a spotted slide for overnight hybridization at 42°C. Slides were scanned with a laser at 532 and 635 nm.
Project description:Mycobacterium tuberculosis (Mtb) depends on protein secretion systems for intracellular survival and virulence. The major virulence determinant and ESX-1 dependent effector protein EsxA causes tissue damage and necrosis which promotes spread and dissemination of the bacterium. We developed a fibroblast survival assay (FSA) that exploits this phenotype by selecting for molecules that protect host cells from Mtb-induced lysis. Hit compounds identified in this high-throughput screen blocked the secretion of EsxA thus promoting phagosome maturation which led to substantially reduced bacterial burden in activated macrophages. Target identification studies performed on these drugs led to discovery of a benzothiophene containing histidine kinase inhibitor and a benzyloxybenzylidine hydrazine compound affecting mycobacterial metal ion homeostasis which enabled us to reveal zinc stress as a signal for EsxA secretion. Collectively, this novel drug screening approach can help to tackle the mounting problem of antibiotic-resistant mycobacteria by largely extending the target spectrum of small molecule libraries.
Project description:Plants growing in soil are challenged by multiple biotic (e.g. pathogens) and abiotic (e.g. heavy metals) stressors. Stress resistance is a key determinant for plants to thrive in the environment. Resistance to pathogens requires innate immunity , whereas tolerance to metal ions is accomplished by mechanisms such as complexation and compartmentation. Some transition metals can enhance plant’s defense against pathogens4,5, but the mechanism remains unclear. Here, we show that an Arabidopsis head-to-head gene pair of intracellular nucleotide-binding leucine-rich repeat (NLR) receptors antagonistically control transition metal-triggered immunity. One NLR, STM2 directly perceives transition metal ions, such as Cd2+, Cu2+ and Zn2+, as a ligand to activate its NAD+ hydrolytic activity and immune responses, triggering enhanced resistance to the soil-borne bacterial wilt pathogen Ralstonia solanacearum. The other NLR, STM1 suppresses STM2 to protect plants from transition metal-triggered immunity and growth inhibition in the presence of excess metals. STM1 also dampens resistance to the pathogen. Our study defines an NLR activated by transition metals and reveals a trade-off between resistance to pathogens and tolerance to transition metals that are pervasive in soil.
Project description:Plants growing in soil are challenged by multiple biotic (e.g. pathogens) and abiotic (e.g. heavy metals) stressors. Stress resistance is a key determinant for plants to thrive in the environment. Resistance to pathogens requires innate immunity 1, whereas tolerance to metal ions is accomplished by mechanisms such as complexation and compartmentation2,3. Some transition metals can enhance plant’s defense against pathogens4,5, but the mechanism remains unclear. Here, we show that an Arabidopsis head-to-head gene pair of intracellular nucleotide-binding leucine-rich repeat (NLR) receptors antagonistically control transition metal-triggered immunity. One NLR, STM2 directly perceives transition metal ions, such as Cd2+, Cu2+ and Zn2+, as a ligand to activate its NAD+ hydrolytic activity and immune responses, triggering enhanced resistance to the soil-borne bacterial wilt pathogen Ralstonia solanacearum. The other NLR, STM1 suppresses STM2 to protect plants from transition metal-triggered immunity and growth inhibition in the presence of excess metals. STM1 also dampens resistance to the pathogen. Our study defines an NLR activated by transition metals and reveals a trade-off between resistance to pathogens and tolerance to transition metals that are pervasive in soil.