Tryptophan biosynthesis (WP165)

Saccharomyces cerevisiae

Biosynthesis of the aromatic amino acids tryptophan, tyrosine, and phenylalanine proceeds via a common pathway to chorismate, at which point the pathway branches (CITS:[Jones][1943992]). One branch proceeds to tryptophan, and the other to tyrosine and phenylalanine (CITS:[Jones]). The series of reactions to chorismate, called the shikimate pathway, and the series of reactions from chorismate to tryptophan have been found to be common to all eukaryotes and prokaryotes studied thus far (as reported in (CITS:[1943992])). In contrast, there appears to be two separate routes from chorismate to tyrosine and phenylalanine, only one of which has been found in S. cerevisiae (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 first step in the tryptophan branch is feedback inhibited by tryptophan, and 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 TRP1 of the tryptophan branch, TYR1 of the tyrosine branch or ARO7 of the tyrosine and phenylalanine branch (CITS:[1943992]). SOURCE: SGD pathways, Based on


Meredith Braymer , Daniela Digles , Egon Willighagen , Martina Summer-Kutmon , Denise Slenter , Kristina Hanspers , and Eric Weitz


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Saccharomyces cerevisiae



Pathway Ontology

tryptophan biosynthetic pathway


Label Type Compact URI Comment
PRPP Metabolite cas:97-55-2
N-(5'-Phosphoribosyl)anthranilate Metabolite chebi:7091
carbon dioxide Metabolite chebi:16526
pyrophosphate Metabolite cas:2466-09-3
chorismate Metabolite chebi:17333
L-serine Metabolite cas:56-45-1
glyceraldehyde-3-phosphate Metabolite cas:591-57-1
anthranilate Metabolite chebi:16567
Indole-3-glycerophosphate Metabolite chebi:18299
L-tryptophan Metabolite cas:73-22-3
pyruvate Metabolite chebi:15361
water Metabolite chebi:15377
L-glutamine Metabolite cas:56-85-9
L-glutamate Metabolite cas:56-86-0
water Metabolite chebi:15377
TRP2 GeneProduct sgd:S000000892
TRP3 GeneProduct sgd:S000001694
TRP3 GeneProduct sgd:S000001694
TRP4 GeneProduct sgd:S000002762
TRP1 GeneProduct sgd:S000002414
TRP5 GeneProduct sgd:S000002994


  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. Nucleotide sequence of Saccharomyces cerevisiae genes TRP2 and TRP3 encoding bifunctional anthranilate synthase: indole-3-glycerol phosphate synthase. Zalkin H, Paluh JL, van Cleemput M, Moye WS, Yanofsky C. J Biol Chem. 1984 Mar 25;259(6):3985–92. PubMed Europe PMC Scholia
  3. A counterselection for the tryptophan pathway in yeast: 5-fluoroanthranilic acid resistance. Toyn JH, Gunyuzlu PL, White WH, Thompson LA, Hollis GF. Yeast. 2000 Apr;16(6):553–60. PubMed Europe PMC Scholia