Commonly usedSaccharomyces cerevisiaestrains (e.g. BY4741, W303) are growth sensitive on synthetic complete medium due to poor leucine uptake

Abstract

It is reported that some of the widely used laboratory strains of Saccharomyces cerevisiae (e.g. W303, BY4741) are sensitive to synthetic media containing all 20 amino acids [e.g. synthetic complete (SC) medium or supplemented minimal medium]. To determine the molecular basis for this unexpected sensitivity, a genomic library was screened and three genes were identified that, when overexpressed, rescue cells from this phenotype. Two of the 'rescuing' genes, BAP2 and TAT1, are related to transport of leucine, and one, LEU2, to synthesis of leucine, showing that sensitivity to SC medium is associated with the leu2 mutation. The sensitive strains seem incapable of transporting leucine when grown on synthetic complete media. This effect of the leu2 mutation should be taken into consideration when analyzing the results of genetic screens and other experiments performed with these strains.

Impaired Uptake and/or Utilization of Leucine bySaccharomyces cerevisiaeIs Suppressed by theSPT15-300Allele of the TATA-Binding Protein Gene

“…Overexpression of TAT2, encoding a high-affinity tryptophan and tyrosine permease (30), yielded yeast cells that acquired a higher tolerance toward ethanol (16). Likewise, the known growth defect of S. cerevisiae leu2 strains (e.g., BY4741) on SC media (8) could be alleviated by overexpression of TAT1 or BAP2 (both encoding amino acid permeases that transport leucine [14,30]) or by reintroducing LEU2 (8). Several studies have demonstrated that the amount of leucine provided in commonly used synthetic media is limiting for growth of leucinerequiring strains, and authors therefore recommend supplementing synthetic media with at least 400 mg leucine per liter (6,29).…”

“…BAP2 (coding for another branched-chain amino acid permease) showed a similar expression profile but was not significant at a FDR of 0.005. These three genes code for permease proteins that are able to transport leucine across the plasma membrane (14,30), and increased expression of TAT1 and BAP2 has been shown to alleviate reduced growth of BY4741 on SC media (8). A majority of the genes involved in leucine utilization and degradation show statistically significant differential expression for the SPT15-300 mutations (a genotype effect, i.e., an effect on gene expression when comparing cells expressing the SPT15-300 allele to those expressing the wildtype allele).…”

Aup1-mediated Regulation of Rtg3 during Mitophagy

“…with an empty vector carrying the LEU2 gene (pRS315) completely abolished caffeine sensitivity. During the course of this study, it was published that laboratory yeast strains show a defect in leucine uptake that is contingent on the metabolic status of the cells (37). This led us to hypothesize that caffeine may adversely affect leucine uptake.…”

Standard YPD, even supplemented with extra nutrients, does not always compensate growth defects of Saccharomyces cerevisiae auxotrophic strains

“…The fact that BY4741 is auxotrophic for leucine while FY1679-14C is not could be one of the reasons for their different behaviour. The poor growth exhibited by BY4741 in our growth conditions seems not to be attributable to the poor leucine uptake reported for this strain and other leucine auxotrophic strains (Cohen and Engelberg 2007). These authors found that growth sensitivity was only seen when BY4741 and other auxotrophic strains were grown in synthetic complete medium (SC) and not when they were grown either in SD or in YPD.…”