1887

Abstract

The first three steps in quinic acid degradation in are catalysed by highly inducible enzymes encoded by a gene cluster regulated by an adjacent control region. Analysis of two non-inducible mutants has been done in diploid strains, where is recessive and all three enzyme activities are fully induced in heterozygous diploids. In contrast, heterozygous diploids show semi-dominance of the mutant allele, giving markedly diminished growth on quinic acid and 30–40% decrease of enzyme induction. Strikingly, the heterozygous diploid grows to the same degree on quinic acid as the heterozygote and shows the same level of enzyme induction, whereas both the homozygous mutant diploids do not grow on quinic acid and show no enzyme induction. Therefore the two mutant genomes complement, identifying two distinct regulatory gene functions. A genetic model is proposed of a negatively acting gene () repressing expression of a positively acting gene (, previously designated ) whose product is in turn required for expression of the three structural genes. The mutation is interpreted to produce an altered repressor insensitive to quinic acid, and the mutation the loss of activator protein. Close similarity in the regulation of the quinic acid gene cluster in suggests that the two types of control mutation, and qal, described for may also reflect two regulatory genes.

Loading

Article metrics loading...

/content/journal/micro/10.1099/00221287-130-3-567
1984-03-01
2021-07-30
Loading full text...

Full text loading...

/deliver/fulltext/micro/130/3/mic-130-3-567.html?itemId=/content/journal/micro/10.1099/00221287-130-3-567&mimeType=html&fmt=ahah

References

  1. Armitt S., Mccullough W., Roberts C. F. 1976; Analysis of acetate non-utilizing (acu) mutants in Aspergillus nidulans. Journal of General Microbiology 92:263–282
    [Google Scholar]
  2. Case M. E., Giles N. H. 1975; Genetic evidence on the organization and action of the qa-1 gene product: a protein regulating the induction of three enzymes in quinate catabolism in Neurospora crassa. Proceedings of the National Academy ofSciences of the United States of America 72:553–557
    [Google Scholar]
  3. Clutterbuck A. J., Ropbr J. A. 1966; A direct determination of nuclear distribution in heterokaryons of Aspergillus nidulans. Genetical Research 7:185–194
    [Google Scholar]
  4. Hawkins A. R., Giles N. H., Kinghorn . 1982; Genetical and biochemical aspects of quinate breakdown in the filamentous fungus Aspergillus nidulans. Biochemical Genetics 20:271–286
    [Google Scholar]
  5. Kinghorn J. R., Hawkins A. R. 1982; Cloning and expression in Escherichia coli K12 of the biosynthetic dehydroquinase function of the aromcluster gene from the eukaryote Aspergillus nidulans. Molecular and General Genetics 186:145–152
    [Google Scholar]
  6. Kushner S. R., Hautala J. A., Jacobson J. N., Giles N. H., Vapnek D. 1977; Expression of the structural gene for catabolic dehydroquinase of Neurospora crassa in Escherichia coli K12. Brookhaven Symposia in Biology 29:297–308
    [Google Scholar]
  7. Littlewood B. S., Chia W., Metzenberg R. L. 1975; Genetic control of phosphate-metabolising enzymes in Neurospora crassa: relationships among regulatory mutations. Genetics 79:419–434
    [Google Scholar]
  8. Qshdaa Y. 1982; Regulatory circuits for gene expression : the metabolism of galactose and phosphate. In The Molecular Biology of the Yeast Saccharomyces. Metabolism and Gene Expression pp. 159–180 Edited by Strathem J. N., Jones E. W., Broach J. R. New York: Cold Spring Harbor Laboratory;
    [Google Scholar]
  9. Patel V. B., Schweizer M., Dykstra C. C., Kushner S. R., Giles N. H. 1981; Genetic organization and transcriptional regulation in the qagene cluster of Neurospora crassa. Proceedings of the National Academy of Sciences of the United States of America 78:5783–5787
    [Google Scholar]
  10. Payton M., Mccullough W., Roberts C. F. 1976; Agar as a carbon source and its effect upon utilization of other carbon sources by acetate nonutilizing(acu) mutants of Aspergillusnidulans. Journal of General Microbiology 94:228–233
    [Google Scholar]
  11. Pontecorvo G., Ropbr J. A., Hemmons L. J., Macdonald K. D., Bufton A. N. J. 1953; The genetics of Aspergillus nidulans. Advances in Genetics 5:141–238
    [Google Scholar]
http://instance.metastore.ingenta.com/content/journal/micro/10.1099/00221287-130-3-567
Loading
/content/journal/micro/10.1099/00221287-130-3-567
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