Skip to main content
NCBI home page
Plant Physiology logoLink to Plant Physiology
. 1981 Feb;67(2):363–366. doi: 10.1104/pp.67.2.363

Control of Pyrimidine Biosynthesis in Synchronously Dividing Cells of Helianthus tuberosus

Neville F Parker 1, John F Jackson 1
PMCID: PMC425684  PMID: 16661676

Abstract

Factors with potential for regulating pyrimidine biosynthesis in plant tissue have been explored in quiescent cells of Helianthus tuberosus induced to divide by auxin addition. Investigations confined to the first highly synchronous cell cycle of the tuber explants revealed that the relative activity of asparate carbamoyltransferase (ACTase) to ornithinecarbamoyltransferase (OCTase) (enzymes competing for carbamoyl phosphate for the pyrimidine and arginine pathways, respectively) changes from 0.5 in quiescent cells to 3.0 by the end of the first cell cycle. This was interpreted as a change in the state of cell function from accumulation of storage arginine to cell division with a concomitant demand for pyrimidine nucleotides for nucleic acid synthesis. The rise in ACTase activity began at the same time as the initiation of DNA synthesis and was dependent on continued DNA synthesis. OCTase activity declined whether or not auxin was added to the medium, whereas ACTase activity was observed to decline only in the absence of DNA synthesis.

The low cellular concentration of the shared substrate, carbamoyl phosphate (2 micromolar), favored utilization of this substrate by the pyrimidine pathway over the arginine pathway because of the low Km (0.08 80 micromolar) for this substrate by ACTase compared to that for OCTase (9.0 millimolar). Unexpectedly, the total concentration of the feedback inhibitor for the pyrimidine pathway, UMP, was found to have more than doubled in dividing tissue at a time when pyrimidine nucleotide demand had increased. It is concluded that compartmentation decreased UMP in the vicinity of ACTase and/or that the extra UMP stabilizes newly synthesized ACTase in preparation for an even greater demand for nucleic acid synthesis in the second and subsequent cell cycles.

Full text

PDF
363

Selected References

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

  1. Caldwell I. C. Ion-exchange chromatography of tissue nucleotides. J Chromatogr. 1969 Oct 28;44(2):331–341. doi: 10.1016/s0021-9673(01)92544-0. [DOI] [PubMed] [Google Scholar]
  2. DURANTON H. Sort des atomes de la molécule d'arginine au cours de sa dégradation par les tissus de topinambour. C R Hebd Seances Acad Sci. 1958 May 28;246(21):3095–3098. [PubMed] [Google Scholar]
  3. HURLBERT R. B., SCHMITZ H., BRUMM A. F., POTTER V. R. Nucleotide metabolism. II. Chromatographic separation of acid-soluble nucleotides. J Biol Chem. 1954 Jul;209(1):23–39. [PubMed] [Google Scholar]
  4. Harland J., Jackson J. F., Yeoman M. M. Changes in some enzymes involved in DNA biosynthesis following induction of division in cultured plant cells. J Cell Sci. 1973 Jul;13(1):121–138. doi: 10.1242/jcs.13.1.121. [DOI] [PubMed] [Google Scholar]
  5. Leigh R. A., Branton D. Isolation of Vacuoles from Root Storage Tissue of Beta vulgaris L. Plant Physiol. 1976 Nov;58(5):656–662. doi: 10.1104/pp.58.5.656. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Lovatt C. J., Albert L. S. Regulation of Pyrimidine Biosynthesis in Intact Cells of Cucurbita pepo. Plant Physiol. 1979 Oct;64(4):562–569. doi: 10.1104/pp.64.4.562. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. O'neal T. D., Naylor A. W. Some regulatory properties of pea leaf carbamoyl phosphate synthetase. Plant Physiol. 1976 Jan;57(1):23–28. doi: 10.1104/pp.57.1.23. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Ong B. L., Jackson J. F. Aspartate transcarbamoylase from Phaseolus aureus. Partial purification and properties. Biochem J. 1972 Sep;129(3):571–581. doi: 10.1042/bj1290571. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Ong B. L., Jackson J. F. Determination of aspartate transcarbamylase by the radioassay of carbamyl 14C-aspartate separated by high-voltage paper electrophoresis. Anal Biochem. 1971 Jul;42(1):289–293. doi: 10.1016/0003-2697(71)90039-x. [DOI] [PubMed] [Google Scholar]
  10. Ong B. L., Jackson J. F. Pyrimidine nucleotide biosynthesis in Phaseolus aureus. Enzymic aspects of the control of carbamoyl phosphate synthesis and utilization. Biochem J. 1972 Sep;129(3):583–593. doi: 10.1042/bj1290583. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Selvendran R. R., Isherwood F. A. Identification of guanosine diphosphate derivatives of D-xylose, D-mannose, D-glucose and D-galactose in mature strawberry leaves. Biochem J. 1967 Nov;105(2):723–728. doi: 10.1042/bj1050723. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Vassef A. A., Flora J. B., Weeks J. G., Bibbs B. S., Schmidt R. R. The effects of enzyme synthesis and stability and of deoxyribonucleic acid replication on the cellular levels of aspartate transcarbamylase during the cell cycle of eucaryote Chlorella. J Biol Chem. 1973 Mar 25;248(6):1976–1985. [PubMed] [Google Scholar]
  13. Williams L. G., Bernhardt S. A., Davis R. H. Evidence for two discrete carbamyl phosphate pools in Neurospora. J Biol Chem. 1971 Feb 25;246(4):973–978. [PubMed] [Google Scholar]

Articles from Plant Physiology are provided here courtesy of Oxford University Press

RESOURCES