1887

Microbiology Society logo

Volume 120, Issue 1

Genetic Regulation of Isocitrate Lyase Activity in Free

Abstract

The formation of the glyoxylate cycle enzymes isocitrate lyase and malate synthase is strongly regulated in and the enzymes are induced at high levels in mycelium grown on acetate and found at low levels in mycelium grown on hexose. A search was made for constitutive mutants forming the enzymes when grown on hexose by the use of a pyruvate carboxylaseless () strain. This strain does not grow on hexose since it requires a source of C tricarboxylic acid cycle intermediates and it was hoped that among revertants selected for growth on hexose some may effect C synthesis by the constitutive formation of the glyoxylate cycle enzymes.

Four constitutive strains were isolated. Three had no pyruvate carboxylase activity and each was found to contain two new mutations: a suppressor mutation of the pyruvate carboxylase lesion, and a mutation which caused low constitutive isocitrate lyase activity. The greater activities in the constitutive strains were due to interactions between the and the and mutations.

The four low-level constitutive mutations defined two genes affecting isocitrate lyase formation. Recessive mutations in (linkage group IV; three alleles) caused 10-fold increased activities in sucrose-grown mycelium, as did a semi-dominant mutation in (linkage group I). The genes are not linked to (structural gene for isocitrate lyase) and did not detectably affect the formation of either malate synthase or acetyl-CoA synthase, the structural gene () for which is tightly linked to There was a synergistic interaction in the double mutant ; Two alternative interpretations of the genes remain open: one is a model for genetic regulation with negative ( gene product) and positive ( gene product) elements; the other is endogenous induction due to the accumulation of metabolites resulting from the unidentified metabolic lesions. We did not find any mutations uninducible for isocitrate lyase amongst acetate non-utilizing mutants.

A fifth isocitrate lyase constitutive mutant was isolated in the wild-type strain. The mutant contained another recessive mutation () in the gene.

The high constitutive isocitrate lyase activities in ; double mutants did not provide replacement of the C requirement in a pyruvate carboxylaseless strain since the triple mutant did not grow on sucrose. Revertants of this strain selected for growth on sucrose again contained suppressor mutations of the lesion and the high constitutive activities for malate synthase decreased as known mutant genes were replaced. The nature of the suppressor gene function(s) providing an alternative source of C intermediates for growth is not known.

  • Received:
  • Revised:
  • Published Online:
© Society for General Microbiology, 1980
Loading

Article metrics loading...

/content/journal/micro/10.1099/00221287-120-1-67
1980-09-01
2024-04-24
Loading full text...

Full text loading...

/deliver/fulltext/micro/120/1/mic-120-1-67.html?itemId=/content/journal/micro/10.1099/00221287-120-1-67&mimeType=html&fmt=ahah

References

  1. Alderson T., Hartley M. J. 1969; Specificity for spontaneous and induced forward mutation at several gene loci in Aspergillus nidulans. Mutation Research 8:255–264
     [Google Scholar]
  2. Armitt S., McCullough W., Roberts C. F. 1976; Analysis of acetate non-utilizing (acu) mutants in Aspergillus nidulans. Journal of GeneralMicrobidogy 92:263–282
     [Google Scholar]
  3. Bartnik E., Weglenski P. 1974; Regulation of arginine catabolism in Aspergillus nidulans. Nature London: 250:590–592
     [Google Scholar]
  4. Brice C. B., Kornberg H. L. 1968; Genetic control of isocitrate lyase activity in Escherichia coli. Journal of Bacteriology 96:2185–2186
     [Google Scholar]
  5. Bushell M. E., Bull A. T. 1974; Anaplerotic carbon dioxide fixation in steady state and nonsteady state fungal cultures. Proceedings of the Society for General Microbiology 1:69
     [Google Scholar]
  6. Clutterbuck A. J. 1974; Aspergillus nidulans. In Handbook of Genetics 1 pp. 447–510 King R. C. Edited by New York:: Plenum Press.;
     [Google Scholar]
  7. Falmange P., Vanderwinkel E., Wiame J. M. 1965; Mise en évidence de deux malate synthases chez Escherichia coli. Biochimica et biophysica acta 99:246–258
     [Google Scholar]
  8. Giles N. H. 1978; The organisation, function, and evolution of gene clusters in eukaryotes. American Naturalist 112:641–657
     [Google Scholar]
  9. Hynes M. J. 1977; Induction of the acetamidase of Aspergillus nidulans by acetate metabolism. Journal of Bacteriology 131:770–775
     [Google Scholar]
  10. Kelly J. M., Hynes M. J. 1977; Increased and decreased sensitivity to carbon catabolite repression of enzymes of acetate metabolism in mutants of Aspergillus nidulans. Molecular and General Genetics 156:87–92
     [Google Scholar]
  11. Kornberg H. L. 1966a; Anaplerotic sequences and their role in metabolism. Essays in Biochemistry 2:1–31
     [Google Scholar]
  12. Kornberg H. L. 1966b; The role and control of the glyoxylate cycle in Escherichia coli. Biochemical Journal 99:1–11
     [Google Scholar]
  13. Miller A. L., Atkinson D. E. 1972; Response of yeast pyruvate carboxylase to the adenylate energy charge and other regulatory parameters. Archives of Biochemistry and Biophysics 152:531–538
     [Google Scholar]
  14. Pateman J. A., Kjnghorn J. R. 1977; Genetic regulation of nitrogen metabolism. In Genetics and Physiology of Aspergillus pp. 203–241 Smith J. E., Pateman J. A. Edited by London & New York:: Academic Press.;
     [Google Scholar]
  15. Payton M., McCullough W., Roberts C. F. 1976; Agar as a carbon source and its effect upon the utilization of other carbon sources by acetate non-utiliizing (acu) mutants of Aspergillus nidulans. Journal of General Microbiology 94:228–233
     [Google Scholar]
  16. Pontecorvo G., Roper J. A., Hemmons L. J., Macdonald K. D., Bufton A.W.J. 1953; The genetics of Aspergillus nidulans. Advances in Genetics 5:141–238
     [Google Scholar]
  17. Skinner V. M., Armitt S. 1972; Mutants of Aspergillus nidulans lacking pyruvate carboxylase. FEBS Letters 20:16–18
     [Google Scholar]
  18. Syrett P. J., Merrett M. J., Bocks S. H. 1963; Enzymes of the glyoxylate cycle in Chlorella vulgaris. Journal of Experimental Botany 14:249–264
     [Google Scholar]
  19. Vanderwinkel E., Liard P., Ramos F., Wiame J. M. 1963; Genetic control of the regulation of isocitrate lyase and malate synthase in Escherichia coli K12. Biochemical and Biophysical Research Communications 12:157–162
     [Google Scholar]
  20. Waldron C., Roberts C. F. 1974; Cold-sensitive mutants in Aspergillus nidulans. I. Isolation and general characterisation. Molecular and General Genetics 134:99–113
     [Google Scholar]
http://instance.metastore.ingenta.com/content/journal/micro/10.1099/00221287-120-1-67
Loading
Genetic Regulation of Isocitrate Lyase Activity in Aspergillus nidulans
Microbiology 120, 67 (1980); https://doi.org/10.1099/00221287-120-1-67
/content/journal/micro/10.1099/00221287-120-1-67
/content/journal/micro/10.1099/00221287-120-1-67
Loading

Data & Media loading...

Most cited Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error