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. 1987 Nov;85(3):845–849. doi: 10.1104/pp.85.3.845

Tabtoxinine-β-Lactam Transport into Cultured Corn Cells 1

Uptake via an Amino Acid Transport System

Daniel R Bush 1,2, Pat J Langston-Unkefer 1
PMCID: PMC1054350  PMID: 16665788

Abstract

Tabtoxinine-β-lactam (T-β-L), a unique amino acid, is a toxin produced by several closely related pathovars of Pseudomonas syringae. These chlorosis-inducing pathogens establish themselves in the apoplastic space of their hosts where they release the toxin. We have examined the transport of T-β-L into cultured corn (Zea mays cv Black Mexican) cells using [14C]T-β-L. The pH optimum of the uptake of the toxin was between 4.0 and 5.5 pH units. Toxin uptake was inhibited by the protonophore, carbonyl cyanide m-chlorophenyl hydrazone, and by the sulfhydryl re-agent, N-ethylmaleimide. Tabtoxinine-β-lactam transport exhibited saturation kinetics that were described by the Michaelis-Menton equation for toxin concentrations of 1 millimolar and less. However, the transport of toxin in concentrations greater than 1 millimolar was not described by Michaelis-Menten kinetics. Glutamate and alanine exhibited similar transport kinetics with a transition to non-Michaelis-Menten kinetics when the amino acid concentration exceeded 1 millimolar. Hill numbers for glutamate, alanine, and T-β-L ranged from 0.6 to 0.8. Methionine, alanine, tyrosine, glutamine, glutamate, and arginine were inhibitors of toxin transport. Alanine was a competitive inhibitor of the transport of T-β-L and of glutamate. The data are consistent with T-β-L being transported into the plant cell through an amino acid transport system.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Bush D. R., Jacobson L. Potassium transport in suspension culture cells and protoplasts of carrot. Plant Physiol. 1986 Aug;81(4):1022–1026. doi: 10.1104/pp.81.4.1022. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Carlson P. S. Methionine sulfoximine--resistant mutants of tobacco. Science. 1973 Jun 29;180(4093):1366–1368. doi: 10.1126/science.180.4093.1366. [DOI] [PubMed] [Google Scholar]
  3. Despeghel J. P., Delrot S. Energetics of Amino Acid Uptake by Vicia faba Leaf Tissues. Plant Physiol. 1983 Jan;71(1):1–6. doi: 10.1104/pp.71.1.1. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Frantz T. A., Peterson D. M., Durbin R. D. Sources of ammonium in oat leaves treated with tabtoxin or methionine sulfoximine. Plant Physiol. 1982 Feb;69(2):345–348. doi: 10.1104/pp.69.2.345. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Harrington H. M., Berry S. L., Henke R. R. Amino Acid Transport into Cultured Tobacco Cells: II. EFFECT OF CALCIUM. Plant Physiol. 1981 Feb;67(2):379–384. doi: 10.1104/pp.67.2.379. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Langston-Unkefer P. J., Robinson A. C., Knight T. J., Durbin R. D. Inactivation of pea seed glutamine synthetase by the toxin, tabtoxinine-beta-lactam. J Biol Chem. 1987 Feb 5;262(4):1608–1613. [PubMed] [Google Scholar]
  7. Langston-Unkefer P. L., Macy P. A., Durbin R. D. Inactivation of Glutamine Synthetase by Tabtoxinine-beta-lactam : Effects of Substrates and pH. Plant Physiol. 1984 Sep;76(1):71–74. doi: 10.1104/pp.76.1.71. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Meins F., Jr, Abrams M. L. How methionine and glutamine prevent inhibition of growth by methionine sulfoximine. Biochim Biophys Acta. 1972 Apr 14;266(1):307–311. doi: 10.1016/0005-2736(72)90146-0. [DOI] [PubMed] [Google Scholar]
  9. Neet K. E. Cooperativity in enzyme function: equilibrium and kinetic aspects. Methods Enzymol. 1980;64:139–192. doi: 10.1016/s0076-6879(80)64009-9. [DOI] [PubMed] [Google Scholar]
  10. Puritch G. S., Barker A. V. Structure and function of tomato leaf chloroplasts during ammonium toxicity. Plant Physiol. 1967 Sep;42(9):1229–1238. doi: 10.1104/pp.42.9.1229. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Sinden S. L., Durbin R. D. Glutamine synthetase inhibition: possible mode of action of wildfire toxin from Pseudomonas tabaci. Nature. 1968 Jul 27;219(5152):379–380. doi: 10.1038/219379a0. [DOI] [PubMed] [Google Scholar]
  12. Thomas M. D., Langston-Unkefer P. J., Uchytil T. F., Durbin R. D. Inhibition of Glutamine Synthetase from Pea by Tabtoxinine-beta-lactam. Plant Physiol. 1983 Apr;71(4):912–915. doi: 10.1104/pp.71.4.912. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. WOOLLEY D. W., PRINGLE R. B., BRAUN A. C. Isolation of the phytopathogenic toxin of Pseudomonas tabaci, an antagonist of methionine. J Biol Chem. 1952 May;197(1):409–417. [PubMed] [Google Scholar]

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