Antisense transcription is associated with expression of metal resistance determinants in Cupriavidus metallidurans CH34.

Cupriavidus metallidurans is able to thrive in metal-rich environments but also survives metal starvation. Expression of metal resistance determinants in C. metallidurans was investigated on a global scale.

The efflux system CdfX exports zinc that cannot be transported by ZntA in .

is able to survive exposure to high concentrations of transition metals, but is also able to grow under metal starvation conditions. A prerequisite of cellular zinc homeostasis is a flow equilibrium combining zinc uptake and efflux processes. The mutant strain ∆e4 of the parental plasmid-free strain AE104 with a deletion of all four chromosomally encoded genes of previously known efflux systems ZntA, CadA, DmeF, and FieF was still able to efflux zinc in a pulse-chase experiment, indicating the existence of a fifth efflux system.

Uncovering mathematics teachers' instructional anticipations in a digital one-to-one environment: A modified UTAUT study.

More and more digital technologies are being integrated into school learning, and one strategy by policymakers to reinforce this trend is employing digital one-to-one approaches. For digital technologies to be fruitfully integrated into school-based learning scenarios, teachers and their anticipations are key. In our study, we want to explore how internal, external and technological factors affect the instructional anticipations of mathematics teachers in a digital one-to-one educational environment.

A gold speciation that adds a second layer to synergistic gold-copper toxicity in .

The metal-resistant bacterium occurs in metal-rich environments. In auriferous soils, the bacterium is challenged by a mixture of copper ions and gold complexes, which exert synergistic toxicity. The previously used, self-made Au(III) solution caused a synergistic toxicity of copper and gold that was based on the inhibition of the CupA-mediated efflux of cytoplasmic Cu(I) by Au(I) in this cellular compartment.

Full Copper Resistance in Cupriavidus metallidurans Requires the Interplay of Many Resistance Systems.

The metal-resistant bacterium Cupriavidus metallidurans uses its copper resistance components to survive the synergistic toxicity of copper ions and gold complexes in auriferous soils. The , , , and determinants encode as central component the Cu(I)-exporting P-type ATPase CupA, the periplasmic Cu(I)-oxidase CopA, the transenvelope efflux system CusCBA, and the Gig system with unknown function, respectively. The interplay of these systems with each other and with glutathione (GSH) was analyzed.

The Sensory Histidine Kinase CusS of Escherichia coli Senses Periplasmic Copper Ions.

Two-component regulatory systems composed of a membrane-bound sensor/sensory histidine kinase (HK) and a cytoplasmic, DNA-binding response regulator (RR) are often associated with transenvelope efflux systems, which export transition metal cations from the periplasm directly out of the cell. Although much work has been done in this field, more evidence is needed for the hypothesis that the respective two-component regulatory systems are indeed sensing periplasmic ions. If so, a regulatory circuit between the concentration of periplasmic metal cations, sensing of these metals, and control of expression of the genes for transenvelope efflux systems that remove periplasmic cations can be assumed.

Interplay between Two-Component Regulatory Systems Is Involved in Control of Cupriavidus metallidurans Metal Resistance Genes.

Metal resistance of Cupriavidus metallidurans is based on determinants that were acquired in the past by horizontal gene transfer during evolution. Some of these determinants encode transmembrane metal efflux systems. Expression of most of the respective genes is controlled by two-component regulatory systems composed of a membrane-bound sensor/sensory histidine kinase (HK) and a cytoplasmic, DNA-binding response regulator (RR).

Importance of RpoD- and Non-RpoD-Dependent Expression of Horizontally Acquired Genes in Cupriavidus metallidurans.

The genome of the metal-resistant, hydrogen-oxidizing bacterium Cupriavidus metallidurans contains a large number of horizontally acquired plasmids and genomic islands that were integrated into its chromosome or chromid. For the CH34 wild-type strain growing under nonchallenging conditions, 5,763 transcriptional starting sequences (TSSs) were determined. Using a custom-built motif discovery software based on hidden Markov models, patterns upstream of the TSSs were identified.

Educational inequality and COVID-19: Who takes advantage of summer schools and other remedial measures?: A latent mediation model analysis based on representative data from Austrian parents of school-aged children.

Unlabelled: In spring 2020, the COVID-19 pandemic triggered a global crisis with far-reaching effects, not least on education. Since the beginning of the pandemic, its impact on learning losses and increasing educational inequality has been widely discussed. While empirical evidence of rising educational inequality and learning loss is steadily growing, at the same time little is known about the families who are interested in remedial measures like summer schools to bridge the negative effects of the pandemic and school closures.

Loss of Mobile Genomic Islands in Metal-Resistant, Hydrogen-Oxidizing Cupriavidus metallidurans.

The genome of the metal-resistant, hydrogen-oxidizing bacterium Cupriavidus metallidurans strain CH34 contains horizontally acquired plasmids and genomic islands. Metal-resistance determinants on the two plasmids may exert genetic dominance over other related determinants. To investigate whether these recessive determinants can be activated in the absence of the dominant ones, the transcriptome of the highly zinc-sensitive deletion mutant Δe4 (Δ) of the plasmid-free parent AE104 was characterized using gene arrays.

Interplay between the Zur Regulon Components and Metal Resistance in Cupriavidus metallidurans.

The Zur regulon is central to zinc homeostasis in the zinc-resistant bacterium It comprises the transcription regulator Zur, the zinc importer ZupT, and three members of the COG0523 family of metal-chaperoning G3E-type GTPases, annotated as CobW1, CobW2, and CobW3. The operon structures of the and loci were determined. To analyze the interplay between the Zur regulon components and metal resistance, deletion mutants were constructed from the wild-type strain CH34 and various other strains.

The third pillar of metal homeostasis in Cupriavidus metallidurans CH34: preferences are controlled by extracytoplasmic function sigma factors.

The role of extracytoplasmic function (ECF) sigma factors in multiple metal homeostasis of the metallophilic bacterium Cupriavidus metallidurans was studied. RNA sequencing was used to predict 3084 operons in the genome of this bacterium, including 11 for ECF sigma factors, and to measure transcript abundances. Mutants carrying multiple deletions in genes for ECF sigma factors were constructed and characterized.

The Components of the Unique Zur Regulon of Cupriavidus metallidurans Mediate Cytoplasmic Zinc Handling.

Zinc is an essential trace element, yet it is toxic at high concentrations. In the betaproteobacterium , the highly efficient removal of surplus zinc from the periplasm is responsible for the outstanding metal resistance of the organism. Rather than having a typical Zur-dependent, high-affinity ATP-binding cassette transporter of the ABC protein superfamily for zinc uptake at low concentrations, has the secondary zinc importer ZupT of the zinc-regulated transporter, iron-regulated transporter (ZRT/IRT)-like protein (ZIP) family.

Characterization of the Δ7 Mutant of with Deletions of Seven Secondary Metal Uptake Systems.

Central to the ability of to maintain its metal homoeostasis is the metal transportome, composed of uptake and efflux systems. Seven secondary metal import systems, ZupT, PitA, CorA, CorA, CorA, ZntB, and HoxN, interact and are at the core of the metal uptake transportome. The 7-fold deletion mutant Δ7 () of parent strain AE104 is still able to maintain its cellular metal content, although at the cost of reduced fitness (M.

Synthesis of nickel-iron hydrogenase in Cupriavidus metallidurans is controlled by metal-dependent silencing and un-silencing of genomic islands.

Cupriavidus metallidurans CH34 is able to grow autotrophically as a hydrogen-oxidizing bacterium and produces nickel-dependent hydrogenases, even under heterotrophic conditions. Loss of its two native plasmids resulted in inability of the resulting strain AE104 to synthesize the hydrogenases and to grow autotrophically in phosphate-poor, Tris-buffered mineral salts medium (TMM). Three of eleven previously identified catabolic genomic islands (CMGIs; Van Houdt et al.

Response of CnrX from Cupriavidus metallidurans CH34 to nickel binding.

Resistance to high concentration of nickel ions is mediated in Cupriavidus metallidurans by the CnrCBA transenvelope efflux complex. Expression of the cnrCBA genes is regulated by the transmembrane signal transduction complex CnrYXH. Together, the metal sensor CnrX and the transmembrane antisigma factor CnrY control the availability of the extracytoplasmic function sigma factor CnrH.

Survival of Escherichia coli cells on solid copper surfaces is increased by glutathione.

Bacteria are rapidly killed on solid copper surfaces, so this material could be useful to limit the spread of multiple-drug-resistant bacteria in hospitals. In Escherichia coli, the DNA-protecting Dps protein and the NADH:ubiquinone oxidoreductase II Ndh were not involved in tolerance to copper ions or survival on solid copper surfaces. Decreased copper tolerance under anaerobic growth conditions in the presence of ascorbate and with melibiose as the carbon source indicated that sodium-dependent symport systems may provide an import route for Cu(I) into the cytoplasm.

FurC regulates expression of zupT for the central zinc importer ZupT of Cupriavidus metallidurans.

The zinc importer ZupT is required for the efficient allocation of zinc to zinc-dependent proteins in the metal-resistant bacterium Cupriavidus metallidurans but not for zinc import per se. The expression of zupT is upregulated under conditions of zinc starvation. C.

Metal sensing and signal transduction by CnrX from Cupriavidus metallidurans CH34: role of the only methionine assessed by a functional, spectroscopic, and theoretical study.

When CnrX, the periplasmic sensor protein in the CnrYXH transmembrane signal transduction complex of Cupriavidus metallidurans CH34, binds the cognate metal ions Ni(II) or Co(II), the ECF-type sigma factor CnrH is made available in the cytoplasm for the RNA-polymerase to initiate transcription at the cnrYp and cnrCp promoters. Ni(II) or Co(II) are sensed by a metal-binding site with a N3O2S coordination sphere with octahedral geometry, where S stands for the thioether sulfur of the only methionine (Met123) residue of CnrX. The M123A-CnrX derivative has dramatically reduced signal propagation in response to metal sensing while the X-ray structure of Ni-bound M123A-CnrXs showed that the metal-binding site was not affected by the mutation.

Influence of copper resistance determinants on gold transformation by Cupriavidus metallidurans strain CH34.

Cupriavidus metallidurans is associated with gold grains and may be involved in their formation. Gold(III) complexes influence the transcriptome of C. metallidurans (F.

Effect of Different Metal Ions on the Biological Properties of Cefadroxil.

The effect of different metal ions on the intestinal transport and the antibacterial activity of cefadroxil [(6R,7R)-7-{[(2R)-2-amino-2-(4-hydroxyphenyl)acetyl]amino}-3-methyl-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid] was investigated.

Mechanisms of gold biomineralization in the bacterium Cupriavidus metallidurans.

While the role of microorganisms as main drivers of metal mobility and mineral formation under Earth surface conditions is now widely accepted, the formation of secondary gold (Au) is commonly attributed to abiotic processes. Here we report that the biomineralization of Au nanoparticles in the metallophillic bacterium Cupriavidus metallidurans CH34 is the result of Au-regulated gene expression leading to the energy-dependent reductive precipitation of toxic Au(III)-complexes. C.

Preparation, physicochemical characterization and biological evaluation of cefodizime metal ion complexes.

Objectives: Cefodizime is a broad spectrum cephalosporin belonging to the third generation agents. In this study, attention has been paid to the preparation, physicochemical characterization and biological evaluation of new Cu2+, Zn2+, Fe3+, Co2+ and Al3+ complexes of cefodizime.

Methods: The stoichiometrics and the mode of bonding of the complexes were deduced from their elemental and metal analysis, electrical conductivity measurements, UV-vis, infrared and Raman spectroscopic investigations.

Cadmium toxicity in glutathione mutants of Escherichia coli.

The higher affinity of Cd(2+) for sulfur compounds than for nitrogen and oxygen led to the theoretical consideration that cadmium toxicity should result mainly from the binding of Cd(2+) to sulfide, thiol groups, and sulfur-rich complex compounds rather than from Cd(2+) replacement of transition-metal cations from nitrogen- or oxygen-rich biological compounds. This hypothesis was tested by using Escherichia coli for a global transcriptome analysis of cells synthesizing glutathione (GSH; wild type), gamma-glutamylcysteine (DeltagshB mutant), or neither of the two cellular thiols (DeltagshA mutant). The resulting data, some of which were validated by quantitative reverse transcription-PCR, were sorted using the KEGG (Kyoto Encyclopedia of Genes and Genomes) orthology system, which groups genes hierarchically with respect to the cellular functions of their respective products.

Contribution of extracytoplasmic function sigma factors to transition metal homeostasis in Cupriavidus metallidurans strain CH34.

Cupriavidus metallidurans strain CH34 is a highly metal-resistant bacterium that contains 11 sigma factors of the extracytoplasmic function (ECF) protein family, which can be subgrouped into the ECF:FecI 1, ECF:FecI 2, ECF:RpoE and '(ECF)' clusters. To analyze the contribution of these 11 sigma factors to metal resistance, upregulation of the respective genes was measured by quantitative real-time reverse transcriptase polymerase chain reaction (qRT-PCR). As determined by RT-PCR, the ECF sigma factor genes were part of two- to tetra-cistronic operons, each containing genes for the sigma factor plus one or two antisigma factors.