Self-protection of Pseudomonas syringae pv. 'tabaci' from its toxin, tabtoxinine-beta-lactam
| Autor: | T J Knight, R D Durbin, P J Langston-Unkefer |
|---|---|
| Rok vydání: | 1987 |
| Předmět: |
Biology
medicine.disease_cause Microbiology Glutathione Synthase chemistry.chemical_compound Biosynthesis Methionine Sulfoximine Pseudomonas Glutamine synthetase medicine Pseudomonas syringae Beta (finance) Molecular Biology Toxin Azetines Biological Transport Drug Resistance Microbial biology.organism_classification Adenosine Monophosphate chemistry Inactivation Metabolic Pseudomonadales Azetidines bacteria Research Article Pseudomonadaceae |
| Zdroj: | Journal of Bacteriology. 169:1954-1959 |
| ISSN: | 1098-5530 0021-9193 |
| DOI: | 10.1128/jb.169.5.1954-1959.1987 |
| Popis: | An extracellular toxin, tabtoxinine-beta-lactam (T beta L), is produced by Pseudomonas syringae pv. "tabaci." This toxin irreversibly inhibits its target, glutamine synthetase; yet P. syringae pv. "tabaci" retains significant amounts of glutamine synthetase activity during toxin production in culture. As part of our investigation of the self-protection of P. syringae pv. "tabaci," we compared the effects of T beta L on Tox+ (T beta L-producing, insensitive to T beta L) and Tox- (T beta L nonproducing, sensitive to T beta L) strains. The extent of protection afforded to the Tox- strain when induced to adenylylate glutamine synthetase was tested. We concluded that an additional protection mechanism was required. A detoxification activity was found in the Tox+ strain which opens the beta-lactam ring of T beta L to produce the inactive, open-chain form, tabtoxinine. Whole cells of the Tox+ strain incubated for 24 h with [14C]T beta L (0.276 mumol/3 X 10(10) cells) contained [14C]tabtoxinine (0.056 mumol), and the medium contained T beta L (0.226 mumol). Extracts of spheroplasts of the Tox+ stain also converted T beta L to tabtoxinine, whereas extracts of the Tox- strain did not alter T beta L. The conversion was time dependent and stoichiometric and was destroyed by boiling for 30 min or by the addition of 5 mM EDTA. Penicillin, a possible substrate and competitive inhibitor of this lactamase activity, inhibited the conversion of T beta L to tabtoxinine. Periplasmic fluid did not catalyze the conversion of T beta L. |
| Databáze: | OpenAIRE |
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