1887

Abstract

The oleaginous fungus possesses at least six isoforms of malic enzyme (EC 1.1.1.40), a key lipogenic enzyme in filamentous fungi. These isoforms were detected using a specific stain for activity after native PAGE of cell extracts. Only one isoform (isoform IV) was associated with lipid accumulation, appearing only after N-exhaustion from the medium (which is a pre-requisite for lipid accumulation) in glucose-growing cells. Isoforms I, II, V and VI were involved in anaerobic growth and only appeared under O-limited conditions. Isoform III appeared to be constitutive and was formed under conditions of active (balanced) growth and is therefore thought to play a crucial role in basic metabolism. Growth on acetate increased the amount of cell lipid (from 25–27% in glucose-grown cells to 37–38% in acetate-grown cells) accumulated by and this was associated with the appearance of isoform IV of malic enzyme prior to N-exhaustion in these cultures. Amino acid sequence analysis of isoforms III and IV suggests that these two malic enzymes may be encoded by a single gene and that isoform IV is formed from isoform III by post-translational modification initiated by either N-limitation (when glucose was the carbon source) or growth on acetate as the sole carbon source.

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2001-06-01
2019-12-05
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References

  1. Boles, E., Jong-Gubbels, P. & Pronk, J. T. ( 1998; ). Identification and characterization of MAE1, the Saccharomyces cerevisiae structural gene encoding mitochondrial malic enzyme. J Bacteriol 180, 2875-2882.
    [Google Scholar]
  2. Bradford, M. M. ( 1976; ). A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal Biochem 72, 248-254.[CrossRef]
    [Google Scholar]
  3. Chaney, A. L. & Marbach, E. P. ( 1962; ). Modified reagents for the determination of ammonium and urea. Clin Chem 8, 130-132.
    [Google Scholar]
  4. Chang, G. G., Wang, J. K., Huang, T. M., Lee, H. J., Chou, W. Y. & Meng, C. L. ( 1991; ). Purification and characterization of the cytosolic NADP+-dependent malic enzyme from human cancer cell line. Eur J Biochem 202, 681-688.[CrossRef]
    [Google Scholar]
  5. Du Preez, J. C., Immelman, M., Kock, J. L. F. & Killian, S. G. ( 1997; ). The effect of acetic acid concentration on the growth and production of gamma-linolenic acid by Mucor circinelloides CBS 203.28 in fed-batch culture. World J Microbiol Biotechnol 13, 81-87.[CrossRef]
    [Google Scholar]
  6. Evans, C. T. & Ratledge, C. ( 1985; ). Possible regulatory roles of ATP:citrate lyase, malic enzyme and AMP deaminase in lipid Rhodosporidium toruloides CBS 14. Can J Microbiol 31, 1000-1005.[CrossRef]
    [Google Scholar]
  7. Folch, J., Lees, M. & Sloane-Stanley, G. H. ( 1957; ). A simple method for the isolation of total lipides from animal tissues. J Biol Chem 226, 497-509.
    [Google Scholar]
  8. Frenkel, R. ( 1975; ). Regulation and physiological functions of malic enzymes. Curr Top Cell Regul 9, 157-181.
    [Google Scholar]
  9. Hames, B. D. ( 1985; ). An introduction to polyacrylamide gel electrophoresis of proteins. In Gel Electrophoresis of Proteins: a Practical Approach , pp. 1-91. Edited by B. D. Hames & D. Rickwood. Oxford:IRL Press.
  10. Hodnett, D. W., Fantozzi, D. A., Thurmond, D. C., Klautky, S. A., MacPhee, K. G., Estrem, S. T., Xu, G. & Goodridge, A. G. ( 1996; ). The chicken malic enzyme gene: structural organization and identification of triiodothyronine response elements in the 5′-flanking DNA. Arch Biochem Biophys 334, 309-324.[CrossRef]
    [Google Scholar]
  11. Hsu, R. Y. & Lardy, H. A. ( 1969; ). Malic enzyme. Methods Enzymol 13, 230-235.
    [Google Scholar]
  12. Kendrick, A. & Ratledge, C. ( 1992; ). Lipid formation in the oleaginous mould Entomophthora exitalis grown in continuous culture: effects of growth rate, temperature and dissolved oxygen tension on polyunsaturated fatty acids. Appl Microbiol Biotechnol 37, 18-22.
    [Google Scholar]
  13. McCullough, W. & Roberts, C. F. ( 1974; ). The role of malic enzyme in Aspergillus nidulans. FEBS Lett 41, 238-242.[CrossRef]
    [Google Scholar]
  14. Ochoa, S., Mehler, A. H. & Kornberg, A. ( 1947; ). Reversible oxidative decarboxylation of malic acid. J Biol Chem 167, 871-872.
    [Google Scholar]
  15. Ratledge, C. & Wynn, J. P. ( 2000; ). Understanding microbial obesity. SIM News 50, 181-185.
    [Google Scholar]
  16. Savitha, J., Wynn, J. P. & Ratledge, C. ( 1997; ). Malic enzyme: its purification and characterization from Mucor circinelloides and occurrence in other oleaginous fungi. World J Microbiol Biotechnol 13, 7-9.[CrossRef]
    [Google Scholar]
  17. Viljoen, M., Subden, R. E., Krizus, A. & Van Vuuren, H. J. J. ( 1994; ). Molecular analysis of the malic enzyme gene (mae2) of Schizosaccharomyces pombe. Yeast 10, 613-624.[CrossRef]
    [Google Scholar]
  18. Walter, M. H., Grima-Pettenati, J. & Feuillet, C. ( 1994; ). Characterization of the bean (Phaseolus vulgaris L.) malic enzyme gene. Eur J Biochem 224, 999-1009.[CrossRef]
    [Google Scholar]
  19. Wynn, J. P. & Ratledge, C. ( 1997; ). Malic enzyme is a major source of NADPH for lipid accumulation by Aspergillus nidulans. Microbiology 143, 253-257.[CrossRef]
    [Google Scholar]
  20. Wynn, J. P. & Ratledge, C. ( 2000; ). Evidence that the rate-limiting step for the biosynthesis of arachidonic acid in Mortierella alpina is at the level of the 18:3 to 20:3 elongase. Microbiology 146, 2325-2331.
    [Google Scholar]
  21. Wynn, J. P., Kendrick, A. & Ratledge, C. ( 1997; ). Sesamol as an inhibitor of growth and lipid metabolism in Mucor circinelloides via its action on malic enzyme. Lipids 32, 605-610.[CrossRef]
    [Google Scholar]
  22. Wynn, J. P., Hamid, A. A. & Ratledge, C. ( 1999; ). The role of malic enzyme in the regulation of lipid accumulation in filamentous fungi. Microbiology 145, 1911-1917.[CrossRef]
    [Google Scholar]
  23. Zink, M. W. ( 1972; ). Regulation of the two malic enzymes in Neurospora crassa. Can J Microbiol 18, 611-617.[CrossRef]
    [Google Scholar]
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