Specific induction by glycine of the gene for the P‐subunit of glycine decarboxylase from Saccharomyces cerevisiae

The glycine decarboxylase complex (GDC) is composed of four subunits referred to as H-, L-, P-, and T-proteins. The Saccharomyces cerevisiae GCV2 gene, encoding the P-protein has been cloned by complementation of the gsd2 mutation which prevents cells converting glycine to serine or using glycine as the sole nitrogen source. The gene, located on the right arm of chromosome XIII adjacent to TPS1, encodes a product with a M(r) of 114385. Expression of GCV2 was induced by the addition of more than 200 microM glycine in the medium, and a maximal sixfold induction occurred above 1 mM. This response was specific to glycine and was not observed for any other amino acid. Under the same conditions, the intracellular level of glycine increased up to 30-fold. The levels of P- and L-protein transcripts and GDC activity were also elevated in cells grown in the presence of glycine. Deletion analysis of the GCV2 promoter delimited the control region which contains putative regulatory sites for GCN4 and GLN3 transcription factors.