1887

Abstract

The flow of carbon to α-acetolactate in K12 is shown to involve the endogenous pool of α-ketobutyrate (α-KB). In vivo, the acetohydroxy acid synthase (AHAS) isoenzymes have an affinity for α-KB sufficiently high that α-acetolactate production is severely limited when α-KB is supplied exogenously. The ability of threonine deaminase to make α-KB is correlated with the synthesis of the AHAS isoenzymes. Mutations in that alter the catalytic and allosteric properties of threonine deaminase affect α-KB production and the expression of the AHAS isoenzymes in a direct way. The mutation results in a feedback-hypersensitive threonine deaminase and slow α-KB and AHAS production. A spontaneous revertant of an strain expressing a feedback-resistant threonine deaminase produces α-KB and AHAS more quickly. A physiological role for the activator (valine) site on threonine deaminase is proposed and valine is shown to increase α-KB production in vivo. Valine can thus regulate its own biosynthetic pathway without jeopardizing the production of isoleucine. The physiological implications of the role of α-KB in the biosynthesis of acetolactate are discussed.

Loading

Article metrics loading...

/content/journal/micro/10.1099/00221287-127-1-19
1981-11-01
2024-03-28
Loading full text...

Full text loading...

/deliver/fulltext/micro/127/1/mic-127-1-19.html?itemId=/content/journal/micro/10.1099/00221287-127-1-19&mimeType=html&fmt=ahah

References

  1. Bachmann B., Low K. B. 1980; Linkage map of Escherichia coli K12. , 6. Microbiological Reviews 44:1–56
    [Google Scholar]
  2. Blatt J., Jackson J. 1978; Enhanced allosteric regulation of threonine deaminase and acetohydroxy acid synthase from Escherichia coli in a permeabilized cell assay system. Biochimica et biophysica acta 526:267–275
    [Google Scholar]
  3. Blatt J., Pledger W., Umbarger H. E. 1972; Isoleucine and valine metabolism in Escherichia coli. XX. Multiple forms of acetohydroxy acid synthase. Biochemical and Biophysical Research Communications 48:444–450
    [Google Scholar]
  4. Calhoun D. 1976; Threonine deaminase from Escherichia coli: feedback-hypersensitive enzyme from a genetic regulatory mutant. Journal of Bacteriology 126:56–63
    [Google Scholar]
  5. Changeux J.-P. 1963; Allosteric interactions on biosynthetic l-threonine deaminase from E. coli K12. Cold Spring Harbor Symposia on Quantitative Biology 28:497–504
    [Google Scholar]
  6. Defelice M., Levinthal M. 1977; The acetohydroxy acid synthase III isoenzyme of Escherichia coli K-12: regulation of synthesis by leucine. Biochemical and Biophysical Research Communications 79:82–87
    [Google Scholar]
  7. Defelice M., Guardiola J., Esposito B., Iaccarino M. 1974; Structural genes for a newly recognized acetolactate synthase in Escherichia coli K-12. Journal of Bacteriology 120:1068–1077
    [Google Scholar]
  8. Defelice M., Squires C., Levinthal M., Guardiola J., Lamberti A., Iaccarino M. 1977; Growth inhibition of Escherichia coli K-12 by valine: a consequence of a regulatory pattern. Molecular and General Genetics 156:1–7
    [Google Scholar]
  9. Defelice M., Newman T., Levinthal M. 1978a; Regulation of synthesis of the acetohydroxy acid synthase I isoenzyme of Escherichia coli K-12. Biochimica et biophysica acta 541:1–8
    [Google Scholar]
  10. Defelice M., Squires C., Levinthal M. 1978b; A comparative study of the acetohydroxy acid synthase isoenzymes of Escherichia coli K-12. Biochimica et biophysica acta 541:9–17
    [Google Scholar]
  11. Favre R., Wiater A., Puppo S., Iaccarino M., Noelle R., Freundlich M. 1976; Expression of a valine-resistant acetolactate synthase activity mediated by the ilvO and ilvG genes of Escherichia coli K-12. Molecular and General Genetics 143:243–252
    [Google Scholar]
  12. Groves W., Davis F., Sells B. 1968; Spectro-photometric determination of microgram quantities of protein without nucleic acid interference. Analytical Biochemistry 22:195–210
    [Google Scholar]
  13. Guardiola J., Defelice M., Iaccarino M. 1974; Mutant of Escherichia coli K-12 missing acetolactate synthase activity. Journal of Bacteriology 120:536–538
    [Google Scholar]
  14. Guardiola J., Defelice M., Lamberti A., Iaccarino M. 1977; The acetolactate synthase isoenzymes of Escherichia coli K-12. Molecular and General Genetics 156:17–25
    [Google Scholar]
  15. Hofler J. G., Burns R. O. 1978; Threonine deaminase from Salmonella typhimurium. Journal of Biological Chemistry 253:1245–1251
    [Google Scholar]
  16. Kline E., Brown C., Coleman W., Umbarger H. E. 1974; Regulation of isoleucine-valine biosynthesis in an ilvDAC deletion strain of Escherichia coli K-12. Biochemical and Biophysical Research Communications 57:1144–1151
    [Google Scholar]
  17. Leavitt R., Umbarger H. E. 1962; Isoleucine and valine metabolism in Escherichia coli K-12. XI. Valine inhibition of growth of Escherichia coli strain K-12. Journal of Bacteriology 83:624–630
    [Google Scholar]
  18. Levinthal M., Williams L., Levinthal M., Umbarger H. E. 1973; Role of threonine deaminase in the regulation of isoleucine and valine biosynthesis. Nature New Biology 246:65–68
    [Google Scholar]
  19. Levinthal M., Levinthal M., Williams L. 1976; The regulation of the ilvADGE operon: evidence for positive control by threonine deaminase. Journal of Molecular Biology 102:453–465
    [Google Scholar]
  20. O’Neill L., Freundlich M. 1972; Two forms of biosynthetic acetohydroxy acid synthase in Salmonella typhimurium. Biochemical and Biophysical Research Communications 48:437–443
    [Google Scholar]
  21. Rosner J. 1972; Formation induction and curing of bacteriophage P1 lysogens. Virology 48:679–689
    [Google Scholar]
  22. Shaw K. J., Berg C. M. 1980; Substrate channeling: α-ketobutyrate inhibition of acetohydroxy acid synthase in Salmonella typhimurium. Journal of Bacteriology 143:1509–1512
    [Google Scholar]
  23. Squires C. H. 1979 Control of carbon flow to isoleucine and valine: the role of threonine deaminase and the acetohydroxy acid synthase isoenzymes of Escherichia coli K-12. Ph.D. thesis Purdue University, U.S.A.:
    [Google Scholar]
  24. Vogel H., Bonner D. 1956; Acetylornithinase of Escherichia coli: partial purification and some properties. Journal of Biological Chemistry 218:97–106
    [Google Scholar]
  25. Vonder Haar R., Umbarger H. E. 1972; Isoleucine and valine metabolism in Escherichia coli. XIX. Inhibition of isoleucine biosynthesis by glycyl-l-leucine. Journal of Bacteriology 112:142–147
    [Google Scholar]
  26. Willshaw G., Tristam H. 1975; Inhibition of Escherichia coli isoleucine biosynthesis by isoleucine tetrazole. Journal of Bacteriology 123:862–870
    [Google Scholar]
http://instance.metastore.ingenta.com/content/journal/micro/10.1099/00221287-127-1-19
Loading
/content/journal/micro/10.1099/00221287-127-1-19
Loading

Data & Media loading...

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