Abstract
The levels of the five enzymes required for isoleucine and valine synthesis were examined under several growth conditions in strain K-12 of Escherichia coli and mutants derived from it. In strains with wild type repressibility, the same pattern of derepression was found on limiting isoleucine as is found to be constitutive in strain Tir-8, which has an altered isoleucine-activating enzyme. Homoserine dehydrogenase, which is essential for the biosynthesis of threonine and is normally derepressed on limiting isoleucine or threonine, is also derepressed in strain Tir-8. Threonine deaminase and homoserine dehydrogenase were partially repressed in strain Tir-8 by very high levels of isoleucine, but were not further derepressed over levels in minimal medium by limiting isoleucine.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- FREUNDLICH M. Multivalent repression in the biosynthesis of threonine in Salmonella typhimurium and Escherichia coli. Biochem Biophys Res Commun. 1963 Feb 6;10:277–282. doi: 10.1016/0006-291x(63)90430-3. [DOI] [PubMed] [Google Scholar]
- LEAVITT R. I., UMBARGER H. E. Isoleucine and valine metabolism in Escherichia coli. XI. Valine inhibition of the growth of Escherichia coli strain K-12. J Bacteriol. 1962 Mar;83:624–630. doi: 10.1128/jb.83.3.624-630.1962. [DOI] [PMC free article] [PubMed] [Google Scholar]
- RAMAKRISHNAN T., ADELBERG E. A. REGULATORY MECHANISMS IN THE BIOSYNTHESIS OF ISOLEUCINE AND VALINE. II. IDENTIFICATION OF TWO OPERATOR GENES. J Bacteriol. 1965 Mar;89:654–660. doi: 10.1128/jb.89.3.654-660.1965. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Szentirmai A., Szentirmai M., Umbarger H. E. Isoleucine and valine metabolism of Escherichia coli. XV. Biochemical properties of mutants resistant to thiaisoleucine. J Bacteriol. 1968 May;95(5):1672–1679. doi: 10.1128/jb.95.5.1672-1679.1968. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Szentirmai A., Umbarger H. E. Isoleucine and valine metabolism of Escherichia coli. XIV. Effect of thiaisoleucine. J Bacteriol. 1968 May;95(5):1666–1671. doi: 10.1128/jb.95.5.1666-1671.1968. [DOI] [PMC free article] [PubMed] [Google Scholar]