Transport and metabolic effects of alpha-aminoisobutyric acid in Saccharomyces cerevisiae.

Abstract

alpha-Aminoisobutyric acid is actively transported into yeast cells by the general amino acid transport system. The system exhibits a Km for alpha-aminoisobutyric acid of 270 microM, a Vmax of 24 nmol/min per mg cells (dry weight), and a pH optimum of 4.1-4.3. alpha-Aminoisobutyric acid is also transported by a minor system(s) with a Vmax of 1.7 nmol/min per mg cells. Transport occurs against a concentration gradient with the concentration ratio reaching over 1000:1 (in/out). The alpha-aminoisobutyric acid is not significantly metabolized or incorporated into protein after an 18 h incubation. alpha-Aminoisobutyric acid inhibits cell growth when a poor nitrogen source such as proline is provided but not with good nitrogen sources such as NH+4. During nitrogen starvation alpha-aminoisobutyric acid strongly inhibits the synthesis of the nitrogen catabolite repression sensitive enzyme, asparaginase II. Studies with a mutant yeast strain (GDH-CR) suggest that alpha-aminoisobutyric acid inhibition of asparaginase II synthesis occurs because alpha-aminoisobutyric acid is an effective inhibitor of protein synthesis in nitrogen starved cells.

• Authors: K W Kim, R J Roon
• Journal: Biochimica et biophysica acta (Biochim Biophys Acta) Vol. 719 Issue 2 Pg. 356-62 (Nov 24 1982) ISSN: 0006-3002 [Print] Netherlands
• PMID: 6758863 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Amino Acids
• Aminoisobutyric Acids
• 2-aminoisobutyric acid

Topics

• Amino Acids (metabolism, pharmacology)
• Aminoisobutyric Acids (metabolism, pharmacology)
• Biological Transport
• Kinetics
• Saccharomyces cerevisiae (drug effects, growth & development, metabolism)