Abstract
The regulation of the formation of isoleucine-valine biosynthetic enzymes was examined to elucidate the mechanism of isoleucine-valine accumulation by α-aminobutyric acid-resistant (abu-r) mutants of Serratia marcescens. In the isoleucine-valine auxotroph, l-threonine dehydratase, acetohydroxy acid synthetase, and transaminase B were repressed when isoleucine, valine, and leucine were simultaneously added to minimal medium. These enzymes were derepressed at the limitation of any single branched-chain amino acid. Pantothenate, which stimulated growth of this auxotroph, had no effect on the enzyme levels. It became evident from these results that in S. marcescens isoleucine-valine biosynthetic enzymes are subject to multivalent repression by three branched-chain amino acids. The abu-r mutants had high enzyme levels in minimal medium, with or without three branched-chain amino acids. Therefore, in abu-r mutants, isoleucine-valine biosynthetic enzymes are genetically derepressed. This derepression was considered to be the primary cause for valine accumulation and increased isoleucine accumulation.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Arfin S. M., Ratzkin B., Umbarger H. E. The metabolism of valine and isoleucine in Escherichia coli. XVII. The role of induction in the derepression of acetohydroxy acid isomeroreductase. Biochem Biophys Res Commun. 1969 Dec 4;37(6):902–908. doi: 10.1016/0006-291x(69)90216-2. [DOI] [PubMed] [Google Scholar]
- BAUERLE R. H., FRUENDLICH M., STORMER F. C., UMBARGER H. E. CONTROL OF ISOLEUCINE, VALINE AND LEUCINE BIOSYNTHESIS. II. ENDPRODUCT INHIBITION BY VALINE OF ACETOHYDROXY ACID SYNTHETASE IN SALMONELLA TYPHIMURIUM. Biochim Biophys Acta. 1964 Oct 23;92:142–149. [PubMed] [Google Scholar]
- Dwyer S. B., Umbarger H. E. Isoleucine and valine metabolism of Escherichia coli. XVI. Pattern of multivalent repression in strain K-12. J Bacteriol. 1968 May;95(5):1680–1684. doi: 10.1128/jb.95.5.1680-1684.1968. [DOI] [PMC free article] [PubMed] [Google Scholar]
- FREUNDLICH M., BURNS R. O., UMBARGER H. E. Control of isoleucine, valine, and leucine biosynthesis. I. Multivalent repression. Proc Natl Acad Sci U S A. 1962 Oct 15;48:1804–1808. doi: 10.1073/pnas.48.10.1804. [DOI] [PMC free article] [PubMed] [Google Scholar]
- KISUMI M. Studies on the isoleucine fermentation. I. Screening of organisms and investigation of cultural conditions. J Biochem. 1962 Dec;52:390–399. doi: 10.1093/oxfordjournals.jbchem.a127635. [DOI] [PubMed] [Google Scholar]
- Kisumi M., Kato J., Komatsubara S., Chibata I. Increase in isoleucine accumulation by alpha-aminobutyric acid-resistant mutants of Serratia marcescens. Appl Microbiol. 1971 Apr;21(4):569–574. doi: 10.1128/am.21.4.569-574.1971. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kisumi M., Komatsubara S., Chibata I. Valine accumulation by alpha-aminobutyric acid-resistant mutants of Serratia marcescens. J Bacteriol. 1971 May;106(2):493–499. doi: 10.1128/jb.106.2.493-499.1971. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kisumi M., Komatsubara S., Sugiura M., Chibata I. Isoleucine hydroxamate, an isoleucine antagonist. J Bacteriol. 1971 Sep;107(3):741–745. doi: 10.1128/jb.107.3.741-745.1971. [DOI] [PMC free article] [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]
- UMBARGER H. E., BROWN B. Isoleucine and valine metabolism in Escherichia coli. V. Antagonism between isoleucine and valine. J Bacteriol. 1955 Aug;70(2):241–248. doi: 10.1128/jb.70.2.241-248.1955. [DOI] [PMC free article] [PubMed] [Google Scholar]