Peptide transport in yeast: utilization of leucine- and lysine-containing peptides by Saccharomyces cerevisiae

Abstract

A variety of leucine-containing diand tripeptides and two lysine-containing dipeptides supported the growth of strain Z1-2D, a leucine, lysine auxotroph of Saccharomyces cerevisiae. However, (Lys)2, (Lys)3, (Lys)4, and (Lys)5 as well as Gly-Leu-Gly, three tetra-and one pentapeptide containing leucine were not utilized by the mutant. Cellular peptidases released leucine or lysine from all of these non-growth-supporting peptides, suggesting that the failure of strain Zl-2D to utilize these compounds reflects their failure to enter the yeast. Competition studies employing phenylalanine or non-leucine-containing peptides showed that the uptake of peptides into S. cerevisiae Z1-2D is distinct from that of amino acids and that diand oligopeptides may share a common transport system. The failure of strain Z1-2D to utilize any peptide larger than (Leu)3 may indicate a transport size limit. Such a size limit would influence the construction of models that explain the action of yeast mating factors.The transport and utilization of peptides have been investigated extensively in Escherichia coli (1,7,14,16) and the mammalian gut (1,7,11,16). The only previously published reports of peptide transport in Saccharomyces cerevisiae deal with the uptake of methioninecontaining peptides by a strain G1333, a methionine auxotroph (4, 12). Information concerning the effect of such factors as amino acid sequence, derivatization of end groups, and peptide length on peptide utilization was determined by using strain G1333. Preliminary studies with this organism, however, left unanswered many important questions concerning the structural requirements for peptide transport in S. cerevisiae. To determine whether peptides comprised entirely of residues other than methionine could also enter S. cerevisiae and to learn more about the structural requirements for peptide transport in this organism, we examined peptide utilization in another auxotroph of this eucaryote.This report deals with transport in S. cerevisiae Z1-2D, a strain that requires both lysine and leucine. In a parallel investigation, we have followed the uptake of radioactively labeled (Met)3 by a wild-type strain of S. cerevisiae (3). MATERIALS AND METHODSYeast strain and growth conditions. Strain Zi-2D, a lys leu auxotroph of S. cerevisiae, was re-ceived from Nasim Khan, Brooklyn College, City University of New York. This haploid strain was derived from a cross between strains KC-372 (X. Mortimer, University of California, Berkeley) and 1323-1B (D. C. Hawthorne, University of Washington, Seattle). The minimal growth medium used for all growth experiments was yeast nitrogen base without amino acids (Difco Laboratories, Detroit, Mich.). This medium was prepared in a ten-timesconcentrated form (6.7 g of yeast nitrogen base in 100 ml of water), 5 g of dextrose was added, and the solution was filter sterilized (Nalge, 0.22 ,um) and refrigerated. All amino acids and peptides were filter sterilized.The strain was maintained on slants composed of 1% yeast extract, 2% peptone, 2% dext...

An Arabidopsis Peptide Transporter Is a Member of a New Class of Membrane Transport Proteins

“…An exception to the observed broad substrate specificity is the inability of highly basic peptides to be transported. Peptides containing three or more lysines did not support the growth of PB1X-9B transformed with either AtPTR2 or PTR2; this is also consistent with previous work on yeast (Lichliter et al, 1976;Marder et al, 1977) and plants (Higgins andPayne, 1978b, 1978c;Sopanen et al, 1978).…”

Amino Acid Metabolism by Yeasts and Lactic Acid Bacteria during Bread Dough Fermentation

“…They also serve as an important source of bread flavor precursors (Spicher and Nierle, 1988). During dough fermentation, some species of Saccharomyces (Marder et al, 1977), lactobacilli-Lactobacillur brevis var. lindneri, L. fructivorans and L. farciminis- (Spicher and SchrGder, 1979) and streptococci-Streptococcus terrnophilus- (Desmazeaud and Hernier, 1973) evidence an important demand for amino acids.…”

The Role of Small Wort Peptides in Brewing Fermentations

“…It was observed that di-and tripeptides that constitute methionine are actively transported into the cells, whereas equal numbers of residual peptides containing glycine were not preferred by the yeast. Studies by Marder et al 12 corroborated these observations reporting that the growth responses for peptides of different sequence might reflect variations in affinity for the peptide transport system. In addition, the amino acid side chains of a peptide may determine its effectiveness as an inhibitor.…”

“…The degree of growth enhancement and the length of the lag period prior to peptide utilization were found to be dependent on both the nature of the amino acid used and the oligopeptide quality. Although growth will be limited when the rate of nutrient peptide supply falls below that needed for optimal protein synthesis, it is difficult to understand why competition should lead to varied lag periods rather than varied growth rates and the simple competitive mechanism described by Marder et al 12 appears to be inadequate to explain the specificity in the observed growth inhibitions. The good growth peptides always exhibit a slight lag phase (5 to 7 h), when their utilization is compared with individual amino acids.…”