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. 1996 Feb;110(2):431–438. doi: 10.1104/pp.110.2.431

Transfer RNA Is the Source of Extracellular Isopentenyladenine in a Ti-Plasmidless Strain of Agrobacterium tumefaciens.

J Gray 1, S B Gelvin 1, R Meilan 1, R O Morris 1
PMCID: PMC157737  PMID: 12226194

Abstract

Even in the absence of the classical Ti plasmid-encoded cytokinin biosynthetic genes ipt and tzs, Agrobacterium tumefaciens strains still release significant amounts of the cytokinin isopentenyladenine (iP) into the culture medium (R.W. Kaiss-Chapman and R.O. Morris [1977] Biochem Biophys Res Commun 76: 453-459). A potential source of the iP is isopentenylated transfer RNA (tRNA), which, in turn, is synthesized by the activity of tRNA:isopentenyltransferase encoded by the bacterial miaA gene. To determine whether secreted iP had its origin in isopentenylated tRNA, a miaA- deletion/insertion mutant was prepared and reconstructed in Agrobacterium tumefaciens in vivo. The mutant no longer possessed tRNA:isopentenylation activity and no longer released iP into the extracellular medium. Transfer RNA therefore makes a small but significant contribution to the total amount of cytokinin normally secreted by Agrobacterium strains. tRNA-mediated synthesis may also account for cytokinin production by other plant-associated bacteria, such as Rhizobia, that have been reported to secrete similarly low levels of nonhydroxylated cytokinins.

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Selected References

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

  1. Akiyoshi D. E., Regier D. A., Gordon M. P. Nucleotide sequence of the tzs gene from Pseudomonas solanacearum strain K60. Nucleic Acids Res. 1989 Nov 11;17(21):8886–8886. doi: 10.1093/nar/17.21.8886. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Barry G. F., Rogers S. G., Fraley R. T., Brand L. Identification of a cloned cytokinin biosynthetic gene. Proc Natl Acad Sci U S A. 1984 Aug;81(15):4776–4780. doi: 10.1073/pnas.81.15.4776. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Chen C. M., Melitz D. K. Cytokinin biosynthesis in a cell-free system from cytokinin-autotrophic tobacco tissue cultures. FEBS Lett. 1979 Nov 1;107(1):15–20. doi: 10.1016/0014-5793(79)80452-4. [DOI] [PubMed] [Google Scholar]
  4. Cherayil J. D., Lipsett M. N. Zeatin ribonucleosides in the transfer ribonucleic acid of Rhizobium leguminosarum, Agrobacterium tumefaciens, Corynebacterium fascians, and Erwinia amylovora. J Bacteriol. 1977 Sep;131(3):741–744. doi: 10.1128/jb.131.3.741-744.1977. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Connolly D. M., Winkler M. E. Genetic and physiological relationships among the miaA gene, 2-methylthio-N6-(delta 2-isopentenyl)-adenosine tRNA modification, and spontaneous mutagenesis in Escherichia coli K-12. J Bacteriol. 1989 Jun;171(6):3233–3246. doi: 10.1128/jb.171.6.3233-3246.1989. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Crespi M., Messens E., Caplan A. B., van Montagu M., Desomer J. Fasciation induction by the phytopathogen Rhodococcus fascians depends upon a linear plasmid encoding a cytokinin synthase gene. EMBO J. 1992 Mar;11(3):795–804. doi: 10.1002/j.1460-2075.1992.tb05116.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Darzins A., Chakrabarty A. M. Cloning of genes controlling alginate biosynthesis from a mucoid cystic fibrosis isolate of Pseudomonas aeruginosa. J Bacteriol. 1984 Jul;159(1):9–18. doi: 10.1128/jb.159.1.9-18.1984. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Dower W. J., Miller J. F., Ragsdale C. W. High efficiency transformation of E. coli by high voltage electroporation. Nucleic Acids Res. 1988 Jul 11;16(13):6127–6145. doi: 10.1093/nar/16.13.6127. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Einset J. W., Skoog F. K. Isolation and identification of ribosyl-cis-zeatin from transfer RNA of Corynebacterium fascians. Biochem Biophys Res Commun. 1977 Dec 21;79(4):1117–1121. doi: 10.1016/0006-291x(77)91121-4. [DOI] [PubMed] [Google Scholar]
  10. Eisenberg S. P., Yarus M., Soll L. The effect of an Escherichia coli regulatory mutation on transfer RNA structure. J Mol Biol. 1979 Nov 25;135(1):111–126. doi: 10.1016/0022-2836(79)90343-7. [DOI] [PubMed] [Google Scholar]
  11. Gray J., Wang J., Gelvin S. B. Mutation of the miaA gene of Agrobacterium tumefaciens results in reduced vir gene expression. J Bacteriol. 1992 Feb;174(4):1086–1098. doi: 10.1128/jb.174.4.1086-1098.1992. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Kaiss-Chapman R. W., Morris R. O. Trans-zeatin in culture filtrates of Agrobacterium tumefaciens. Biochem Biophys Res Commun. 1976 May 23;76(2):453–459. doi: 10.1016/0006-291x(77)90746-x. [DOI] [PubMed] [Google Scholar]
  13. Morris R. O., Regier D. A., Olson R. M., Jr, Struxness L. A., Armstrong D. J. Distribution of cytokinin-active nucleosides in isoaccepting transfer ribonucleic acids from Agrobacterium tumefaciens. Biochemistry. 1981 Oct 13;20(21):6012–6017. doi: 10.1021/bi00524a014. [DOI] [PubMed] [Google Scholar]
  14. Petrullo L. A., Gallagher P. J., Elseviers D. The role of 2-methylthio-N6-isopentenyladenosine in readthrough and suppression of nonsense codons in Escherichia coli. Mol Gen Genet. 1983;190(2):289–294. doi: 10.1007/BF00330653. [DOI] [PubMed] [Google Scholar]
  15. Phillips D. A., Torrey J. G. Studies on cytokinin production by Rhizobium. Plant Physiol. 1972 Jan;49(1):11–15. doi: 10.1104/pp.49.1.11. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Powell G. K., Morris R. O. Nucleotide sequence and expression of a Pseudomonas savastanoi cytokinin biosynthetic gene: homology with Agrobacterium tumefaciens tmr and tzs loci. Nucleic Acids Res. 1986 Mar 25;14(6):2555–2565. doi: 10.1093/nar/14.6.2555. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Regier D. A., Morris R. O. Secretion of trans-zeatin by Agrobacterium tumefaciens: a function determined by the nopaline Ti plasmid. Biochem Biophys Res Commun. 1982 Feb 26;104(4):1560–1566. doi: 10.1016/0006-291x(82)91429-2. [DOI] [PubMed] [Google Scholar]
  18. Sturtevant D. B., Taller B. J. Cytokinin Production by Bradyrhizobium japonicum. Plant Physiol. 1989 Apr;89(4):1247–1252. doi: 10.1104/pp.89.4.1247. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Upadhyaya N. M., Parker C. W., Letham D. S., Scott K. F., Dart P. J. Evidence for Cytokinin Involvement in Rhizobium (IC3342)-Induced Leaf Curl Syndrome of Pigeonpea (Cajanus cajan Millsp.). Plant Physiol. 1991 Apr;95(4):1019–1025. doi: 10.1104/pp.95.4.1019. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Upadhyaya N. M., Scott K. F., Tucker W. T., Watson J. M., Dart P. J. Isolation and characterization of Rhizobium (IC3342) genes that determine leaf curl induction in pigeon pea. Mol Plant Microbe Interact. 1992 Mar-Apr;5(2):129–143. doi: 10.1094/mpmi-5-129. [DOI] [PubMed] [Google Scholar]
  21. Yanisch-Perron C., Vieira J., Messing J. Improved M13 phage cloning vectors and host strains: nucleotide sequences of the M13mp18 and pUC19 vectors. Gene. 1985;33(1):103–119. doi: 10.1016/0378-1119(85)90120-9. [DOI] [PubMed] [Google Scholar]

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