Abstract

The yeast Saccharomyces cerevisiae uses glycine for the synthesis of activated one-carbon units and nitrogen metabolism. The homozygous diploid set of deletion strains includes strains deleted from all the S. cerevisiae non-essential genes (about 4700). This deletion set was screened for strains exhibiting a growth phenotype when glycine was used as the sole nitrogen source (Gmin medium). This screen identified a total of 321 strains. Within the 321 strains, 250 showed a growth defect on Gmin (G- phenotype) whereas 71 exhibited better growth on Gmin (G+ phenotype). Further high-density colony-array analyses established the growth profile for each of the 321 strains on ten different media. These growth profiling experiments identified genes important for various aspects of glycine metabolism. For example vesicular transport from the plasma membrane to the multivesicular body compartment was important for growth in media containing high concentrations of glycine. This suggests that the general amino acid permease (Gap1p) must be targeted to the vacuole for degradation to prevent glycine toxicity. Growth profiling also confirmed the importance of the mitochondrial compartment for glycine metabolism and defined the functional role of CEM1 and YJL046W for lipoate metabolism. This study therefore validated the use of growth profiling data generated using high density colony assays for the study of eukaryotic gene function.