Regulation of dipeptide transport in Saccharomyces cerevisiae by micromolar amino acid concentrations.
AUTOR(ES)
Island, M D
RESUMO
Prototrophic Saccharomyces cerevisiae X2180, when grown on unsupplemented minimal medium, displayed little sensitivity to ethionine- and m-fluorophenylalanine-containing toxic dipeptides. We examined the influence of the 20 naturally occurring amino acids on sensitivity to toxic dipeptides. A number of these amino acids, at concentrations as low as 1 microM (leucine and tryptophan), produced large increases in sensitivity to leucyl-ethionine, alanyl-ethionine, and leucyl-m-fluorophenylalanine. Sensitivity to ethionine and m-fluorophenylalanine remained high under either set of conditions. The addition of 0.15 mM tryptophan to a growing culture resulted in the induction of dipeptide transport, as indicated by a 25-fold increase in the initial rate of L-leucyl-L-[3H]leucine accumulation. This increase, which was prevented by the addition of cycloheximide, began within 30 min and peaked approximately 240 min after a shift to medium containing tryptophan. Comparable increases in peptidase activity were not apparent in crude cell extracts from tryptophan-induced cultures. We concluded that S. cerevisiae possesses a specific mechanism for the induction of dipeptide transport that can respond to very low concentrations of amino acids.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=212111Documentos Relacionados
- Inhibition of amino acid transport by ammonium ion in Saccharomyces cerevisiae.
- Amino Acid Transport in a Polyaromatic Amino Acid Auxotroph of Saccharomyces cerevisiae
- Ammonia regulation of amino acid permeases in Saccharomyces cerevisiae.
- Positive regulation in the general amino acid control of Saccharomyces cerevisiae.
- Amino acid transport and metabolism in nitrogen-starved cells of Saccharomyces cerevisiae.