Threonine biosynthesis (WP331)

Saccharomyces cerevisiae

Threonine biosynthesis as shown here covers the process of converting L-Aspartate into threonine. This pathway is regulated at multiple points by its end product, both via enzyme inhibition and attenuation. There is a three-step pathway that converts L-aspartate into homoserine. Two of the three enzymes that catalyze the first step in this pathway are bifunctional, also serving to catalyze the later step in the pathway. Homoserine feeds into biosynthetic pathways for both threonine and methionine. Fittingly, this pathway is regulated by the outputs of both of those pathways. SOURCE: SGD pathways,


Meredith Braymer , Daniela Digles , Egon Willighagen , Denise Slenter , Alex Pico , and Eric Weitz


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Saccharomyces cerevisiae



Pathway Ontology

threonine biosynthetic pathway


Label Type Compact URI Comment
L-Aspartate Metabolite chebi:17053
H2O Metabolite chebi:15377
L-Aspartate-semialdehyde Metabolite hmdb:HMDB0012249
O-phospho-L-homoserine Metabolite chebi:15961
NADP Metabolite hmdb:HMDB0000217
H+ Metabolite chebi:15378
L-Aspartyl-4-P Metabolite chebi:15836
NADP Metabolite hmdb:HMDB0000217
phosphate Metabolite cas:14265-44-2
NADPH Metabolite cas:53-57-6
L-threonine Metabolite cas:72-19-5
ADP Metabolite cas:58-64-0
ATP Metabolite cas:1927-31-7
NADPH Metabolite cas:53-57-6
ADP Metabolite cas:58-64-0
homoserine Metabolite cas:672-15-1
ATP Metabolite cas:1927-31-7
phosphate Metabolite cas:14265-44-2
HOM3 Protein sgd:S000000854
THR4 Protein sgd:S000000649
THR1 Protein sgd:S000001067
HOM2 Protein sgd:S000002565
HOM6 Protein sgd:S000003900


  1. Saccharomyces cerevisiae homoserine kinase is homologous to prokaryotic homoserine kinases. Schultes NP, Ellington AD, Cherry JM, Szostak JW. Gene. 1990 Dec 15;96(2):177–80. PubMed Europe PMC Scholia
  2. Biochemical evidence that the Saccharomyces cerevisiae THR4 gene encodes threonine synthetase. Ramos C, Calderón IL. FEBS Lett. 1994 Sep 12;351(3):357–9. PubMed Europe PMC Scholia