Leucine biosynthesis (WP180)

Saccharomyces cerevisiae

Yeast cells contain 3 pathways for the synthesis of glutamate. Two pathways are mediated by two isoforms of glutamate dehydrogenase, encoded by GDH1 and GDH3 (CITS: [2989290])(CITS: [9287019]). The third pathway is driven by the combined activities of glutamine synthetase and glutamate synthase, encoded by GLN1 and GLT1, respectively (CITS: [2570348])(CITS: [8923741]). Studies of GDH1 and GDH3 regulation indicate that the cell uses these isoforms under different growth conditions (CITS: [11562373]). Expression of GDH3 is induced by ethanol and repressed by glucose, whereas GDH1 expression is high in either carbon source. Gdh1p uses alpha-ketoglutarate at a higher rate than Gdh3p. Thus, under fermentative growth conditions, Gdh1p drives glutamate biosynthesis, whereas in nonfermentable or limiting carbon sources, Gdh3p is the key isoform involved in balancing distribution of alpha-ketoglutarate to glutamate biosynthesis and energy metabolism. SOURCE: SGD pathways, http://pathway.yeastgenome.org/server.html


Meredith Braymer , Daniela Digles , Egon Willighagen , Martina Summer-Kutmon , and Eric Weitz


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Saccharomyces cerevisiae



Pathway Ontology

leucine biosynthetic pathway


Label Type Compact URI Comment
acetyl-CoA Metabolite cas:72-89-9
Coenzyme A Metabolite cas:64885-97-8
NADH Metabolite cas:53-84-9
L-leucine Metabolite cas:61-90-5
L-glutamate Metabolite cas:56-86-0
LEU9 GeneProduct sgd:S000005634
LEU4 GeneProduct sgd:S000005048
LEU1 GeneProduct sgd:S000002977
LEU2 GeneProduct sgd:S000000523
BAT2 GeneProduct sgd:S000003909
BAT1 GeneProduct sgd:S000001251


  1. Leucine biosynthesis in fungi: entering metabolism through the back door. Kohlhaw GB. Microbiol Mol Biol Rev. 2003 Mar;67(1):1–15, table of contents. PubMed Europe PMC Scholia