Phenylalanine- and tyrosine-auxotrophic mutants of Saccharomyces cerevisiae impaired in transamination
| Autor: | Ismaïl Iraqui, Stephan Vissers, Antonio Urrestarazu, Marcelle Grenson |
|---|---|
| Rok vydání: | 1998 |
| Předmět: |
Transamination
Phenylpyruvic Acids Phenylalanine Genes Fungal Lyases Saccharomyces cerevisiae Biology Substrate Specificity Fungal Proteins chemistry.chemical_compound Ammonia Kynurenine aminotransferase activity Genetics Aromatic amino acids Urea Tyrosine Amino Acids Molecular Biology Kynurenine Transaminases chemistry.chemical_classification Methionine Culture Media Isoenzymes Phenotype chemistry Biochemistry Leucine |
| Zdroj: | Moleculargeneral genetics : MGG. 257(2) |
| ISSN: | 0026-8925 |
| Popis: | This paper reports the first isolation of Saccharomyces cerevisiae mutants lacking aromatic aminotransferase I activity (aro8), and of aro8 and aro9 double mutants which are auxotrophic for both phenylalanine and tyrosine, because the second mutation, aro9 affects aromatic aminotransferase II. Neither of the single mutants displays any nutritional requirement on minimal ammonia medium. In vitro, aromatic aminotransferase I is active not only with the aromatic amino acids, but also with methionine, alpha-aminoadipate, and leucine when phenylpyruvate is the amino acceptor, and in the reverse reactions with their oxo-acid analogues and phenylalanine as the amino donor. Its contribution amounts to half of the glutamate:2-oxoadipate activity detected in cell-free extracts and the enzyme might be identical to one of the two known alpha-aminoadipate aminotransferases. Aromatic aminotransferase I has properties of a general aminotransferase which, like several aminotransferases of Escherichia coli, may be able to play a role in several otherwise unrelated metabolic pathways. Aromatic aminotransferase II also has a broader substrate specificity than initially described. In particular, it is responsible for all the measured kynurenine aminotransferase activity. Mutants lacking this activity grow very slowly on kynurenine medium. |
| Databáze: | OpenAIRE |
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