Project description:A novel ArsR-SmtB family transcriptional repressor, KmtR, has been characterised from mycobacteria. Mutants of M. tuberculosis lacking kmtR show elevated expression of Rv2025c encoding a deduced CDF-family metal-exporter. KmtR-dependent repression of the cdf and kmtR operator-promoters was alleviated by nickel and cobalt in minimal medium. Electrophoretic mobility shift assays (EMSA) and fluorescence anisotropy (FA) show binding of purified KmtR to nucleotide sequences containing a region of dyad symmetry from the cdf and kmtR operator-promoters. A relatively large deltar(obs) in FA implies formation of high order apo-KmtR(n)-DNA and multiple complexes were detected by EMSA. Incubation of KmtR with cobalt inhibits DNA-complex assembly and metal-protein binding was confirmed by competition against 4-(2-pyridylazo)-resorcinol. KmtR is the second, to NmtR, characterised ArsR-SmtB sensor of nickel and cobalt from M. tuberculosis suggesting special significance for these ions in this pathogen. KmtR-dependent expression is elevated in complete medium with no increase in response to metals, while NmtR retains a response to nickel and cobalt under these conditions. Mixing equimolar apo-KmtR and apo-NmtR with 0.8 equivalents of nickel or cobalt gave nickel- and cobalt-dependent difference emission spectra similar to nickel(0.8)-KmtR and cobalt(0.8)-KmtR, respectively. Thus, KmtR has tighter affinities for nickel and cobalt than NmtR consistent with basal levels of these metals being sensed by KmtR but not NmtR in complete medium. More than a thousand genes encoding ArsR-SmtB related proteins are listed in databases and a proportion can be predicted to detect metals through known allosteric sites. KmtR has none of the previously defined sites. Substitution of His(88), Glu(101), His(102), His(110) or His(111) with Gln generated KmtR-variants that repress the cdf and kmtR operator-promoters even in elevated nickel and cobalt, revealing a new sensory site. Importantly, ArsR-SmtB sequence groupings do not correspond with the different sensory-motifs revealing that only the latter should be used to predict metal-sensing. Data is also available from http://bugs.sgul.ac.uk/E-BUGS-49
Project description:Comparison of transcriptional profiles after exposure of HaCaT cells to WC or WC-Co nanoparticles and respective amount of free cobalt in form of CoCl2 after 3 hours and 3 days of exposure. Genes responding especially to nanoparticles or leached cobalt ions should be determined.
Project description:Nickel compounds, important carcinogens and prime inducers of contact allergy in humans, are potent activators of endothelial cells (ECs). To elucidate the signaling pathways mediating the cellular responses to nickel we performed Affymetrix gene profiling of human primary ECs. Keywords: stress response
Project description:We explored the transcriptome change of Streptococcus suis in the presence of ferrous iron and cobalt by RNA sequencing. The data revealed that expression of a lot of genes was altered to respond to ferrous iron and cobalt toxicity. Moreover, most of the genes differentially expressed in response to cobalt are the same as those in response to ferrous iron.
Project description:Analysis of anti-CD3/anti-CD28 stimulated T cells treated with or without nickel chloride. Nickel is the most important contact allergen in the general population of the industrialized world. Results provide insight into the biological effects of nickel on human CD3+ T cells.
Project description:The goal of this study was to produce a reference transcriptome for the nickel hyperaccumulator Leucocroton havanensis endemic from Cuba and use this transcriptome as a reference to identify genes responding to the presence or the absence of nickel in both roots and shoots of this species
Project description:To identify differentially expressed transcripts between control samples and spontaneous tumors, or control samples and cobalt treated tumors, we collected RNA from male and female B6C3F1 mice from a 2-year inhalation NTP bioassay exposed to 0 or 5 mg/m3 cobalt metal dust. These samples were interrogated with the Affymetrix Mouse Genome 430 2.0 GeneChip Array. A total of 11557 gene transcripts were differentially expressed between control samples and spontaneous tumors, and 12420 gene transcripts were differentially expressed between control samples and treated cobalt tumors (false discovery rate (FDR) < 0.05).