Cysteine biosynthesis from homoserine (WP256)

Saccharomyces cerevisiae

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O-Acetyl-L-homoserine sulfhydrylase participates in an alternative pathway of L-homocysteine synthesis. Cysteine can then be produced by the reverse transsulfuration pathway, which involves the conversion of homocysteine to cysteine with the help of a cystathionine intermediate. This process takes place in two steps: First, cystathionine-synthase (Cys4p) catalyzes a -displacement reaction, whereby the thiol group of homocysteine replaces the hydroxyl group of serine, resulting in the formation of cystathionine. Second, cystathionine-lyase (Cys3p) catalyzes an ,-elimination reaction, which hydrolyzes cystathionine to generate cysteine, -ketobutyrate, and ammonia.

Authors

Meredith Braymer , Egon Willighagen , Martina Summer-Kutmon , Susan Coort , Denise Slenter , Alex Pico , and Eric Weitz

Activity

last edited

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Organisms

Saccharomyces cerevisiae

Communities

Annotations

Pathway Ontology

cysteine metabolic pathway

Participants

Label Type Compact URI Comment
homocysteine Metabolite cas:6027-13-0
cystathionine Metabolite cas:56-88-2
L-cysteine Metabolite cas:52-90-4
acetate Metabolite cas:64-19-7
2-oxobutanoate Metabolite hmdb:HMDB0000005
NH3 Metabolite hmdb:HMDB0000051
homoserine Metabolite cas:672-15-1
acetyl-CoA Metabolite cas:72-89-9
L-serine Metabolite cas:56-45-1
Coenzyme A Metabolite cas:64885-97-8
CYS4 GeneProduct sgd:S000003387
MET17 GeneProduct sgd:S000004294
MET2 GeneProduct sgd:S000005221
CYS3 GeneProduct sgd:S000000010

References