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. 1990 Feb;2(2):153–161. doi: 10.1105/tpc.2.2.153

Fungal toxins bind to the URF13 protein in maize mitochondria and Escherichia coli.

C J Braun 1, J N Siedow 1, C S Levings 3rd 1
PMCID: PMC159872  PMID: 2136632

Abstract

Expression of the maize mitochondrial T-urf13 gene results in a sensitivity to a family of fungal pathotoxins and to methomyl, a structurally unrelated systemic insecticide. Similar effects of pathotoxins and methomyl are observed when T-urf13 is cloned and expressed in Escherichia coli. An interaction between these compounds and the membrane-bound URF13 protein permeabilizes the inner mitochondrial and bacterial plasma membranes. To understand the toxin-URF13 effects, we have investigated whether toxin specifically binds to the URF13 protein. Our studies indicate that toxin binds to the URF13 protein in maize mitochondria and in E. coli expressing URF13. Binding analysis in E. coli reveals cooperative toxin binding. A low level of specific toxin binding is also demonstrated in cms-T and cms-T-restored mitochondria; however, binding does not appear to be cooperative in maize mitochondria. Competition and displacement studies in E. coli demonstrate that toxin binding is reversible and that the toxins and methomyl compete for the same, or for overlapping, binding sites. Two toxin-insensitive URF13 mutants display a diminished capability to bind toxin in E. coli, which identifies residues of URF13 important in toxin binding. A third toxin-insensitive URF13 mutant shows considerable toxin binding in E. coli, demonstrating that toxin binding can occur without causing membrane permeabilization. Our results indicate that toxin-mediated membrane permeabilization only occurs when toxin or methomyl is bound to URF13.

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Selected References

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

  1. Bervillé A., Ghazi A., Charbonnier M., Bonavent J. F. Effects of Methomyl and Helminthosporium maydis Toxin on Matrix Volume, Proton Motive Force, and NAD Accumulation in Maize (Zea mays L.) Mitochondria. Plant Physiol. 1984 Oct;76(2):508–517. doi: 10.1104/pp.76.2.508. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Braun C. J., Siedow J. N., Williams M. E., Levings C. S., 3rd Mutations in the maize mitochondrial T-urf13 gene eliminate sensitivity to a fungal pathotoxin. Proc Natl Acad Sci U S A. 1989 Jun;86(12):4435–4439. doi: 10.1073/pnas.86.12.4435. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Dewey R. E., Levings C. S., 3rd, Timothy D. H. Novel recombinations in the maize mitochondrial genome produce a unique transcriptional unit in the Texas male-sterile cytoplasm. Cell. 1986 Feb 14;44(3):439–449. doi: 10.1016/0092-8674(86)90465-4. [DOI] [PubMed] [Google Scholar]
  4. Holden M. J., Sze H. Helminthosporium maydis T Toxin Increased Membrane Permeability to Ca in Susceptible Corn Mitochondria. Plant Physiol. 1984 May;75(1):235–237. doi: 10.1104/pp.75.1.235. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Klein R. R., Koeppe D. E. Mode of Methomyl and Bipolaris maydis (race T) Toxin in Uncoupling Texas Male-Sterile Cytoplasm Corn Mitochondria. Plant Physiol. 1985 Apr;77(4):912–916. doi: 10.1104/pp.77.4.912. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Koeppe D. E., Cox J. K., Malone C. P. Mitochondrial heredity: a determinant in the toxic response of maize to the insecticide methomyl. Science. 1978 Sep 29;201(4362):1227–1229. doi: 10.1126/science.201.4362.1227. [DOI] [PubMed] [Google Scholar]
  7. Kuo L. C., Zambidis I., Caron C. Triggering of allostery in an enzyme by a point mutation: ornithine transcarbamoylase. Science. 1989 Aug 4;245(4917):522–524. doi: 10.1126/science.2667139. [DOI] [PubMed] [Google Scholar]
  8. LOWRY O. H., ROSEBROUGH N. J., FARR A. L., RANDALL R. J. Protein measurement with the Folin phenol reagent. J Biol Chem. 1951 Nov;193(1):265–275. [PubMed] [Google Scholar]
  9. Matthews D. E., Gregory P., Gracen V. E. Helminthosporium maydis Race T Toxin Induces Leakage of NAD from T Cytoplasm Corn Mitochondria. Plant Physiol. 1979 Jun;63(6):1149–1153. doi: 10.1104/pp.63.6.1149. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Miller R. J., Koeppe D. E. Southern corn leaf blight: susceptible and resistant mitochondria. Science. 1971 Jul 2;173(3991):67–69. doi: 10.1126/science.173.3991.67. [DOI] [PubMed] [Google Scholar]
  11. Munson P. J., Rodbard D. Ligand: a versatile computerized approach for characterization of ligand-binding systems. Anal Biochem. 1980 Sep 1;107(1):220–239. doi: 10.1016/0003-2697(80)90515-1. [DOI] [PubMed] [Google Scholar]
  12. Ogata R. T., McConnell H. M. The binding of a spin-labeled triphosphate to hemoglobin. Cold Spring Harb Symp Quant Biol. 1972;36:325–336. doi: 10.1101/sqb.1972.036.01.043. [DOI] [PubMed] [Google Scholar]
  13. Remaut E., Stanssens P., Fiers W. Plasmid vectors for high-efficiency expression controlled by the PL promoter of coliphage lambda. Gene. 1981 Oct;15(1):81–93. doi: 10.1016/0378-1119(81)90106-2. [DOI] [PubMed] [Google Scholar]
  14. Siedow J. N., Bickett D. M. Binding of butyl gallate to isolated mung bean mitochondria : relationship to inhibition of the alternative pathway. Plant Physiol. 1983 Jun;72(2):339–344. doi: 10.1104/pp.72.2.339. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Wise R. P., Pring D. R., Gengenbach B. G. Mutation to male fertility and toxin insensitivity in Texas (T)-cytoplasm maize is associated with a frameshift in a mitochondrial open reading frame. Proc Natl Acad Sci U S A. 1987 May;84(9):2858–2862. doi: 10.1073/pnas.84.9.2858. [DOI] [PMC free article] [PubMed] [Google Scholar]

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