Phenylalanine biosynthesis (WP194)

Saccharomyces cerevisiae

Biosynthesis of the aromatic amino acids phenylalanine, tyrosine, and tryptophan proceeds via a common pathway to chorismate, at which point the pathway branches (CITS:[Jones][1943992]). One branch proceeds to phenylalanine and tyrosine, and the other to tryptophan (CITS:[Jones]). The phenylalanine and tyrosine branch has one reaction in common, rearrangement of chorismate to prephenate, at which point, the pathway branches again to either phenylalanine or tyrosine (CITS:[1943992])). S. cerevisiae, similar to E. coli, synthesize phenylalanine and tyrosine via the intermediate 4-hydroxyphenylpyruvate and phenylpyruvate, respectively, while some other organisms synthesize them via arogenate (CITS:[1943992]). Aromatic amino acid biosynthesis in S. cerevisiae is controlled by a combination of feedback inhibition, activation of enzyme activity, and regulation of enzyme synthesis (CITS:[Jones][1943992]). The carbon flow through the pathways is regulated primarily at the initial step and the branching points by the terminal end-products. The initial step of chorismate biosynthesis can be catalyzed by two isoenzymes Aro3p or Aro4p, whereby Aro3p is inhibited by phenylalanine, and Aro4p by tyrosine (CITS:[Jones][1943992]). The first step in the phenylalanine-tyrosine branch is feedback inhibited by tyrosine and activated by tryptophan (CITS:[1943992]). The transcriptional activator GCN4 regulates most of the genes encoding for the aromatic amino acid biosynthetic enzymes; however, no GCN4 regulation was found for ARO7 of the phenylalanine and tyrosine and branch, TYR1 of the tyrosine branch, or TRP1 of the tryptophan branch (CITS:[1943992]). SOURCE: SGD pathways, Based on


Meredith Braymer , Daniela Digles , Egon Willighagen , Denise Slenter , Kristina Hanspers , and Eric Weitz


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Saccharomyces cerevisiae



Pathway Ontology

phenylalanine biosynthetic pathway


Label Type Compact URI Comment
L-glutamate Metabolite cas:56-86-0
prephenate Metabolite cas:126-49-8
L-alanine Metabolite chebi:16977
Phenylpyruvate Metabolite chebi:30851
chorismate Metabolite chebi:17333
L-phenylalanine Metabolite chebi:17295
carbon dioxide Metabolite chebi:16526
water Metabolite chebi:15377
2-oxoglutarate Metabolite chebi:16810
pyruvate Metabolite chebi:15361
PHA2 GeneProduct sgd:S000005260
ARO9 GeneProduct sgd:S000001179
ARO8 GeneProduct sgd:S000003170
ARO7 GeneProduct sgd:S000006264


  1. Aromatic amino acid biosynthesis in the yeast Saccharomyces cerevisiae: a model system for the regulation of a eukaryotic biosynthetic pathway. Braus GH. Microbiol Rev. 1991 Sep;55(3):349–70. PubMed Europe PMC Scholia
  2. Phenylalanine- and tyrosine-auxotrophic mutants of Saccharomyces cerevisiae impaired in transamination. Urrestarazu A, Vissers S, Iraqui I, Grenson M. Mol Gen Genet. 1998 Jan;257(2):230–7. PubMed Europe PMC Scholia
  3. Characterisation of Saccharomyces cerevisiae ARO8 and ARO9 genes encoding aromatic aminotransferases I and II reveals a new aminotransferase subfamily. Iraqui I, Vissers S, Cartiaux M, Urrestarazu A. Mol Gen Genet. 1998 Jan;257(2):238–48. PubMed Europe PMC Scholia
  4. Tyrosine and tryptophan act through the same binding site at the dimer interface of yeast chorismate mutase. Schnappauf G, Krappmann S, Braus GH. J Biol Chem. 1998 Jul 3;273(27):17012–7. PubMed Europe PMC Scholia