Toxic component of a toxin-antitoxin (TA) module. The phosphorylation of UDP-N-acetyl-D-glucosamine results in the inhibition of EC 2.5.1.7, UDP-N-acetylglucosamine 1-carboxyvinyltransferase, the first committed step in cell wall synthesis, which is then blocked. The activity of this enzyme is inhibited when the enzyme binds to the cognate epsilon antitoxin.
Toxic component of a toxin-antitoxin (TA) module. The phosphorylation of UDP-N-acetyl-D-glucosamine results in the inhibition of EC 2.5.1.7, UDP-N-acetylglucosamine 1-carboxyvinyltransferase, the first committed step in cell wall synthesis, which is then blocked. The activity of this enzyme is inhibited when the enzyme binds to the cognate epsilon antitoxin.
ngzeta_1 phosphorylates UDP-muramic acid (UNAM) at the 4'-hydroxy group, binding structure analysis of substrate and product. The phosphate group on UNAM is attached to the C4'-OH and not to the C3'-OH group atom, different to what has been described for the hitherto characterized zeta UNAG kinases
the kinase activity is responsible for the toxic function in vivo, because the phosphorylated product inhibits MurA, the enzyme responsible for the first step of peptidoglycan synthesis in bacteria, mechanism, overview
enzyme-substrate interaction analysis, overview. PezT activity is specific for the presence of the 2'-N-acetyl group on the sugar moiety and the stereoisomeric form of UDP-N-acetyl-D-glucosamine, selectivity for UDPglucose and UDP-N-acetylgalactosamine is dramatically reduced
the kinase activity is responsible for the toxic function in vivo, because the phosphorylated product inhibits MurA, the enzyme responsible for the first step of peptidoglycan synthesis in bacteria, mechanism, overview
enzyme-substrate interaction analysis, overview. PezT activity is specific for the presence of the 2'-N-acetyl group on the sugar moiety and the stereoisomeric form of UDP-N-acetyl-D-glucosamine, selectivity for UDPglucose and UDP-N-acetylgalactosamine is dramatically reduced
the kinase activity is responsible for the toxic function in vivo, because the phosphorylated product inhibits MurA, the enzyme responsible for the first step of peptidoglycan synthesis in bacteria, mechanism, overview
enzyme-substrate interaction analysis, overview. PezT activity is specific for the presence of the 2'-N-acetyl group on the sugar moiety and the stereoisomeric form of UDP-N-acetyl-D-glucosamine, selectivity for UDPglucose and UDP-N-acetylgalactosamine is dramatically reduced. UDP-N-acetyl-D-glucosamine binds to a deep cleft at the molecular surface of the zeta toxin. The side chain group of Asp67 forms a hydrogen bond to the 3'-hydroxyl group of the amino sugar moiety of the substrate
UDP-sugar specificity of the recombinant enzyme, overview. Enzyme ng_zeta1 displays broader substrate specificity and phosphorylates multiple UDP-activated sugars that are precursors of peptidoglycan and lipopolysaccharide synthesis. The phosphorylation site of Neisseria zeta-toxin is different from the streptococcal zeta toxins, resulting in a different interference with cell wall synthesis. Arg181 and Arg175 form a positively charged patch in the active site counteracting the negatively charged phosphate groups
neutralization of the bacteriotoxic protein PezT is carried out by complex formation with its cognate antitoxin PezA, proteolytic resistance of PezA once bound to PezT
phosphoryltransfer reaction from ATP/GTP to an unknown substrate is much more likely responsible for toxicity than a simple nucleoside triphosphate hydrolysis
phosphoryltransfer reaction from ATP/GTP to an unknown substrate is much more likely responsible for toxicity than a simple nucleoside triphosphate hydrolysis
free zeta acts as phosphotransferase by using ATP/GTP. In epsilon2zeta2, the toxin zeta is inactivated because the N-terminal helix of the antitoxin epsilon blocks the ATP/GTP-binding site, toxin-antitoxin interactions, overview
free zeta acts as phosphotransferase by using ATP/GTP. In epsilon2zeta2, the toxin zeta is inactivated because the N-terminal helix of the antitoxin epsilon blocks the ATP/GTP-binding site, toxin-antitoxin interactions, overview
neutralization of the bacteriotoxic protein PezT is carried out by complex formation with its cognate antitoxin PezA, proteolytic resistance of PezA once bound to PezT
the kinase activity is responsible for the toxic function in vivo, because the phosphorylated product inhibits MurA, the enzyme responsible for the first step of peptidoglycan synthesis in bacteria, mechanism, overview
the kinase activity is responsible for the toxic function in vivo, because the phosphorylated product inhibits MurA, the enzyme responsible for the first step of peptidoglycan synthesis in bacteria, mechanism, overview
the kinase activity is responsible for the toxic function in vivo, because the phosphorylated product inhibits MurA, the enzyme responsible for the first step of peptidoglycan synthesis in bacteria, mechanism, overview
neutralization of the bacteriotoxic protein PezT is carried out by complex formation with its cognate antitoxin PezA, proteolytic resistance of PezA once bound to PezT
contributes to enforce toxin-induced dormanc. After induction of the zetaY83C toxin the expression of the relA gene is induced. Disruption of RelA is pleotropic, leading to poor growth and accumulation of phenotypic suppressors that increase expression of the other (p)ppGpp synthetase genes, ssa1 and ssa2
association and dissociation kinetics of the PezAT complex, with wild-type and mutant D66T PezT, stopped-flow measurements, femtomolar affinity of PezA and PezT, detailed kinetic analysis of the PezAT interaction determined using rapid mixing methods and time-resolved size exclusion chromatography, overview
most genomes of bacteria contain toxin-antitoxin systems. These gene systems encode a toxic protein and its cognate antitoxin. Members of the epsilon/zeta toxin-antitoxin family are found throughout the genomes of pathogenic bacteria
most genomes of bacteria contain toxin-antitoxin systems. These gene systems encode a toxic protein and its cognate antitoxin. Members of the epsilon/zeta toxin-antitoxin family are found throughout the genomes of pathogenic bacteria
most genomes of bacteria contain toxin-antitoxin systems. These gene systems encode a toxic protein and its cognate antitoxin. Members of the epsilon/zeta toxin-antitoxin family are found throughout the genomes of pathogenic bacteria
ngzeta_1 forms a new subclass of zeta-like toxins. Apart from being encoded on a bicistronic operon and harbouring a P-loop motive, a hallmark for ATP/GTP binding proteins, ngzeta_1 is remarkably different from the hitherto functionally characterized streptococcal zeta toxins in its primary sequence. Especially striking is that the P-loop motive is located much closer to the Cterminus when compared with streptococcal zeta toxins. Also the ngepsilon_1 antitoxin has no similarities to any known epsilon protein
expression of PezT and zeta in Escherichia coli lead to temporary inhibition in cell growth and is therefore seen as triggering cell stasis rather than cell death
ngzeta_1 drains precursors from peptidoglycan synthesis at multiple stages. Under normal conditions cytosolic levels of UNAM regulate peptidoglycan synthesis by a negative feedback loop inhibiting MurA. In contrast, once ngzeta_1 becomes active, MurA, MurB, and MurC are depleted from their substrates. All phosphorylated precursors are dead-end metabolites, but none of them seems to directly inhibit any enzyme of early peptidoglycan synthesis
PezAT chromosomal toxin-antitoxin system of the human pathogen Streptococcus pneumoniae, the toxicity of PezT is counteracted by PezA, which is encoded immediately upstream of pezT and shares weak sequence similarities in the C-terminal region with the epsilon antitoxin. The pezAT genes form a bicistronic operon that is co-transcribed from a sigma70-like promoter upstream of pezA and is negatively autoregulated with PezA functioning as a transcriptional repressor and PezT as a co-repressor. Inactivation of PezT by PezA, in the inactive PezA2PezT2 heterotetrameric protein complex, the nucleotide binding site of PezT is covered by two helices of PezA
the toxin-antitoxin system is not only able to stabilize resistance plasmids but also to promote virulence. It is linked with numerous functions, including growth modulation, genome maintenance, and stress response. Upon antitoxin degradation, the toxin induces cell stasis or death. zeta Toxins are kinases that poison bacteria through global inhibition of peptidoglycan synthesis. zeta Toxins in general phosphorylate the ubiquitous peptidoglycan precursor uridine diphosphate-N-acetylglucosamine, and this activity is counteracted by binding of antitoxin. Mechanism used by zeta toxins to induce programmed cell death in bacteria, overview. PezT phosphorylates the cell wall precursor and inhibits cell wall synthesis
the toxin-antitoxin system is not only able to stabilize resistance plasmids but also to promote virulence. It is linked with numerous functions, including growth modulation, genome maintenance, and stress response. Upon antitoxin degradation, the toxin induces cell stasis or death. zeta Toxins are kinases that poison bacteria through global inhibition of peptidoglycan synthesis. zeta Toxins in general phosphorylate the ubiquitous peptidoglycan precursor uridine diphosphate-N-acetylglucosamine, and this activity is counteracted by binding of antitoxin. Mechanism used by zeta toxins to induce programmed cell death in bacteria, overview. PezT phosphorylates the cell wall precursor and inhibits cell wall synthesis
the toxin-antitoxin system is not only able to stabilize resistance plasmids but also to promote virulence. It is linked with numerous functions, including growth modulation, genome maintenance, and stress response. Upon antitoxin degradation, the toxin induces cell stasis or death. zeta Toxins are kinases that poison bacteria through global inhibition of peptidoglycan synthesis. zeta Toxins in general phosphorylate the ubiquitous peptidoglycan precursor uridine diphosphate-N-acetylglucosamine, and this activity is counteracted by binding of antitoxin. Mechanism used by zeta toxins to induce programmed cell death in bacteria, overview. PezT phosphorylates the cell wall precursor and inhibits cell wall synthesis
toxin zeta inhibits cell wall biosynthesis and may be bactericide in nature, it induces at or near physiological concentrations reversible cessation of Bacillus subtilis proliferation, as protective dormancy, by targeting essential metabolic functions and selects a subpopulation of cells that exhibit non-inheritable tolerance. zeta Toxin induces reversible protective dormancy and permeation to propidium iodide, and expression of epsilon2 antitoxin reverses these effects. At later times, free active zeta decreases synthesis of macromolecules and releases intracellular K+, molecular mechanisms and regulation, overview
toxin zeta is bactericidal for the gram-positive Bacillus subtilis and bacteriostatic for the gram-negative Escherichia coli, counteracted by proper expression of epsilon. Functioning of the omega-epsilon-zeta operon as a stabilizing cassette in Bacillus subtilis and Escherichia coli cells, mechanism, overview
zeta-toxins interfere with cell wall synthesis. The phosphorylation site of Neisseria zeta-toxin is different from the streptococcal zeta toxins, resulting in a different interference with cell wall synthesis. This difference most likely reflects adaptation to the individual cell wall composition of Gram-negative and Gram-positive organisms but also the distinct involvement of cell wall components in virulence
toxin zeta inhibits cell wall biosynthesis and may be bactericide in nature, it induces at or near physiological concentrations reversible cessation of Bacillus subtilis proliferation, as protective dormancy, by targeting essential metabolic functions and selects a subpopulation of cells that exhibit non-inheritable tolerance. zeta Toxin induces reversible protective dormancy and permeation to propidium iodide, and expression of epsilon2 antitoxin reverses these effects. At later times, free active zeta decreases synthesis of macromolecules and releases intracellular K+, molecular mechanisms and regulation, overview
the antitoxin toxin system epsilon/zeta and antibiotic resistance proteins are encoded on the broad-host-range, low-copy-number plasmid pSM19035. Theepsilon2/zeta2 protein complex is biologically nontoxic. The predominant contacts between antitoxin epsilon and toxin zeta involve helix a of epsilon, toxin-antitoxin interactions, overview
the antitoxin toxin system epsilon/zeta and antibiotic resistance proteins are encoded on the broad-host-range, low-copy-number plasmid pSM19035. Theepsilon2/zeta2 protein complex is biologically nontoxic. The predominant contacts between antitoxin epsilon and toxin zeta involve helix a of epsilon, toxin-antitoxin interactions, overview
the pneumococcal chromosomally encoded, class II epsilon zeta antitoxin toxin, PezAT, system is a chromosomally encoded, class II toxin antitoxin system from the human pathogen, assembly and dynamics of the epsilon zeta antitoxin toxin, PezAT association is electrostatically enhanced, overview. Proteolytic removal of the transcriptional repressor domain of PezA, because the C-terminal domains binds to PezT with comparable affinity as full-length protein
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CRYSTALLIZATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
wild-type ng_epsilon1/ng_zeta1 complex with bound substrate UDP-muramic acid and product UDP-muramic acid 4'-phosphate and of selenomethionine-labeled ng_epsilon1/ng_zeta1_K115A complex mutant, X-ray diffraction structure determination and analysis at 2.4-2.8 A resolution
purified recombinant wild-type and selenomethionine-derivated epsilon2/zeta2 protein complexes, X-ray diffraction structure determination and analysis at 1.95 A and 3.1 A resolution, respectively, multiple anomalous diffraction, modeling
deletion of one A in the AAAAAAA tract, which begins at the 78-nt position, results in a frameshift and the stop codon formation after 51 codons, additional mutations are insertion of G after A32 and A111C substitution in one case and A248G substitution in the second one
deletion of one A in the AAAAAAA tract, which begins at the 78-nt position, results in a frameshift and the stop codon formation after 51 codons, additional mutations are insertion of G after A32 and A111C substitution in one case and A248G substitution in the second one
site-directed mutagenesis, the change in the Walker A motif enables cloning and expression of genes K46A and D67T in Escherichia coli without coexpression of the antagonistic gene epsilon
site-directed mutagenesis, the change in the Walker A motif enables cloning and expression of genes K46A and D67T in Escherichia coli without coexpression of the antagonistic gene epsilon
site-directed mutagenesis, the mutant induces the dormant state with equal efficiency as the wild-type toxin independently of the KCl concentration of 5-150 mM. zetaY83C-induced dormancy is characterized by minimal metabolism, with the repression of genes involved in glycolysis such as yqeC, mtlD, glpK, glpD, yvkC, gutP, gntK, gntR, and gntZ. zetaY83C toxin induction also affects ATP and GTP production levels, overview
site-directed mutagenesis, the mutant induces the dormant state with equal efficiency as the wild-type toxin independently of the KCl concentration of 5-150 mM. zetaY83C-induced dormancy is characterized by minimal metabolism, with the repression of genes involved in glycolysis such as yqeC, mtlD, glpK, glpD, yvkC, gutP, gntK, gntR, and gntZ. zetaY83C toxin induction also affects ATP and GTP production levels, overview
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GENERAL STABILITY
ORGANISM
UNIPROT
LITERATURE
overall stability of the chromosomally encoded PezAT TA system, overview. High affinity of PezAT and the resulting stabilization of PezA upon complex formation with PezT seem to impair toxin release by simple dissociation
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PURIFICATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
recombinant fused His-tagged PezT with His-tagged PezA from Escherichia coli BL21(DE3) by nickel affinity chromatography, PezA is cleaved off by thrombin, followed by anion exchange and gel filtration to purifiy PezT and PezA, quantitative real-time RT PCR expression analysis
gene pezT, DNA and amino acid sequence determination and analysis, sequence comparison, co-expression of fused His-tagged PezT with His-tagged PezA in Escherichia coli BL21(DE3). The PezA antitoxin represses transcription from PpezAT and the PezT toxin acts as a co-repressor
gene pezT, recombinant expression of GFP-tagged enzyme in the eukaryotic microalga Chlorella vulgaris strain UMT-M1, Agrobacterium tumefaciens strain LBA4404-mediated co-transformation with recombinant activator and responder vectors, is lethal. Following induction by 17-beta-estradiol for the expression of the toxin-GFP fusion transgenes, algal cells show signs of cellular damage and lysis. Vector construct overview
gene pezT, sequence comparisons, recombinant expression of His-tagged enzyme in Escherichia coli strain BL21(DE3)-RIL, Ngzeta_1 expression in Escherichia coli cells causes a lytic phenotype compensated by ngepsilon_1 coexpression. Growth curves of Escherichia coli C41(DE3) cells expressing ngzeta_1 wild-type and ngzeta_1 mutant K115A show that when ngzeta_1 is expressed in Escherichia coli cells, a strong lytic phenotype 30 min post-induction occurs
the gene is encoded in plasmid pSM19035. The omega-epsilon-zeta operon of this plasmid constitutes a proteic plasmid addiction system in which the epsilon and zeta genes encode an antitoxin and toxin, respectively, while omega plays an autoregulatory function
lethal expression of bacterial toxin-antitoxin system toxins in eukaryotic microalgae, which can form the basis of a novel method for harvesting of microalgal cellular contents. Chlorella vulgaris is a eukaryotic microalga with potential for the production of biofuels. Its thick and rigid cell wall is an impediment to cost-effective, large-scale harvesting of biofuels from these cells
Meinhart, A.; Alonso, J.C.; Straeter, N.; Saenger, W.
Crystal structure of the plasmid maintenance system epsilon/zeta: functional mechanism of toxin zeta and inactivation by epsilon 2 zeta 2 complex formation