Topic
Tabtoxin
About: Tabtoxin is a research topic. Over the lifetime, 85 publications have been published within this topic receiving 3034 citations.
Papers published on a yearly basis
Papers
TL;DR: Genetic reprogramming of peptide and polyketide synthetases has been successful, and portions of the coronatine and syringomycin gene clusters could be valuable resources in developing new antimicrobial agents.
Abstract: Coronatine, syringomycin, syringopeptin, tabtoxin, and phaseolotoxin are the most intensively studied phytotoxins of Pseudomonas syringae, and each contributes significantly to bacterial virulence in plants. Coronatine functions partly as a mimic of methyl jasmonate, a hormone synthesized by plants undergoing biological stress. Syringomycin and syringopeptin form pores in plasma membranes, a process that leads to electrolyte leakage. Tabtoxin and phaseolotoxin are strongly antimicrobial and function by inhibiting glutamine synthetase and ornithine carbamoyltransferase, respectively. Genetic analysis has revealed the mechanisms responsible for toxin biosynthesis. Coronatine biosynthesis requires the cooperation of polyketide and peptide synthetases for the assembly of the coronafacic and coronamic acid moieties, respectively. Tabtoxin is derived from the lysine biosynthetic pathway, whereas syringomycin, syringopeptin, and phaseolotoxin biosynthesis requires peptide synthetases. Activation of phytotoxin synthesis is controlled by diverse environmental factors including plant signal molecules and temperature. Genes involved in the regulation of phytotoxin synthesis have been located within the coronatine and syringomycin gene clusters; however, additional regulatory genes are required for the synthesis of these and other phytotoxins. Global regulatory genes such as gacS modulate phytotoxin production in certain pathovars, indicating the complexity of the regulatory circuits controlling phytotoxin synthesis. The coronatine and syringomycin gene clusters have been intensively characterized and show potential for constructing modified polyketides and peptides. Genetic reprogramming of peptide and polyketide synthetases has been successful, and portions of the coronatine and syringomycin gene clusters could be valuable resources in developing new antimicrobial agents.
898 citations
TL;DR: The transgenic tobacco plants showed high specific-expression of the ttr gene and no chlorotic symptoms caused by tabtoxin treatment or with infection by Pseudomonas syringae pv.
Abstract: Some plant pathogens produce toxins which cause disease in infected plants. One of the pathogenic toxins, tabtoxin, is produced by Pseudomonas syringae pv. tabaci, which causes wildfire of tobacco. A tabtoxin resistance gene (ttr) coding for an acetyltransferase isolated from Pseudomonas syringae pv. tabaci was fused to the 35S promoter of the cauliflower mosaic virus (CaMV) to construct a chimeric gene for introduction into tobacco cells by Agrobacterium-mediated transformation. The transgenic tobacco plants showed high specific-expression of the ttr gene and no chlorotic symptoms caused by tabtoxin treatment or with infection by Pseudomonas syringae pv. tabaci. These results demonstrate a successful approach to obtain disease-resistant plants by detoxification of the pathogenic toxins which play an important role in pathogenesis.
141 citations
TL;DR: Results demonstrated that pyoverdine synthesis and the quorum-sensing system of Pseudomonas syringae pv.
Abstract: To investigate the role of iron uptake mediated by the siderophore pyoverdine in the virulence of the plant pathogen Pseudomonas syringae pv. tabaci 6605, three predicted pyoverdine synthesis-related genes, pvdJ, pvdL, and fpvA, were mutated. The pvdJ, pvdL, and fpvA genes encode the pyoverdine side chain peptide synthetase III L-Thr-L-Ser component, the pyoverdine chromophore synthetase, and the TonB-dependent ferripyoverdine receptor, respectively. The Delta pvdJ and Delta pvdL mutants were unable to produce pyoverdine in mineral salts-glucose medium, which was used for the iron-depleted condition. Furthermore, the Delta pvdJ and Delta pvdL mutants showed lower abilities to produce tabtoxin, extracellular polysaccharide, and acyl homoserine lactones (AHLs), which are quorum-sensing molecules, and consequently had reduced virulence on host tobacco plants. In contrast, all of the mutants had accelerated swarming ability and increased biosurfactant production, suggesting that swarming motility and biosurfactant production might be negatively controlled by pyoverdine. Scanning electron micrographs of the surfaces of tobacco leaves inoculated with the mutant strains revealed only small amounts of extracellular polymeric matrix around these mutants, indicating disruption of the mature biofilm. Tolerance to antibiotics was drastically increased for the Delta pvdL mutant, as for the Delta psyI mutant, which is defective in AHL production. These results demonstrated that pyoverdine synthesis and the quorum-sensing system of Pseudomonas syringae pv. tabaci 6605 are indispensable for virulence in host tobacco infection and that AHL may negatively regulate tolerance to antibiotics.
140 citations
TL;DR: Investigations on the influence of the wildfire toxin on GS obtained from pea, and the effect of L-glutamine in reversing the toxin's effects in intact tobacco leaves and on GS in vitro are reported.
Abstract: TOBACCO wildfire toxin, produced by the phytopathogenic bacterium Pseudomonas tabaci, and methionine sulphoximine (MSO) inhibit the growth of the alga Chlorella vulgaris, and induce chlorosis in leaves of higher plants1. Because both compounds were considered to be structural analogues of methionine, it was postulated that they acted as methionine antimetabolites. Although L-methionine overcame the growth inhibition effect of both the toxin and MSO in Chlorella, it did not prevent chlorosis in higher plants. It has recently been shown that the inhibition of the growth of oat coleoptiles induced by MSO can be reversed by glutamine, but not by methionine2. In animals the wildfire toxin causes convulsions identical to those produced by MSO3; significantly, these two compounds also inhibit cerebral glutamine synthetase (GS)4,5. In view of the similarities exhibited by the two compounds, both in plants and animals, and the findings implicating glutamine metabolism, we felt that a study of the effect of the wildfire toxin on plant GS might provide additional insight into its mode of action. We report here the results of investigations on the influence of the wildfire toxin on GS obtained from pea6, and the effect of L-glutamine in reversing the toxin's effects in intact tobacco leaves and on GS in vitro.
116 citations
TL;DR: A method for the purification of glutamine synthetase from dried peas is presented which gives a 30% yield with a 2,000-fold increase in specific activity and the authenticity and purity of tabt toxinine-β-lactam and tabtoxin were verified.
Abstract: Tabtoxinine-β-lactam, a hydrolytic product of tabtoxin produced by Pseudomonas syringae pv. tabaci , apparently inactivates pea seed glutamine synthetase. Inhibition of the enzyme9s initial velocity is linear over a range of 0.5 to 5 millimolar tabtoxinine-β-lactam in the presence of 10 millimolar glutamate. A method for the purification of glutamine synthetase from dried peas is presented which gives a 30% yield with a 2,000-fold increase in specific activity. A method for obtaining highly purified tabtoxinine-β-lactam and tabtoxin in good yields is also presented. The authenticity and purity of tabtoxinine-β-lactam and tabtoxin were verified by chromatography, biological activity, and 1 H and 13 C nuclear magnetic resonance spectroscopy.
95 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2018 | 1 |
| 2016 | 2 |
| 2015 | 1 |
| 2014 | 1 |
| 2013 | 3 |
| 2012 | 4 |