Cysteine synthase (IPR005856)

Short name: Cys_synth

Overlapping homologous superfamilies

Family relationships


Cysteine synthase (also known as O-acetylserine (thiol)-lyase or O-acetyl-L-serine sulfhydrylase) is the enzyme responsible for the formation of cysteine from O-acetyl-serine and hydrogen sulphide with the concomitant release of acetic acid. In bacteria such two forms of the enzyme are known (genes cysK and cysM) [PMID: 22113557, PMID: 18799456]. CysM differs from CysK in that it can also use thiosulphate instead of sulphide, to produce cysteine.

Beta-cyanoalanine synthase is a mitochondrial cysteine synthase-like protein from plants [PMID: 10889265]. It has cysteine synthase activity, but the cyanoalanine synthesis reaction is more efficient than the cysteine synthase activity.

GO terms

Biological Process

GO:0006535 cysteine biosynthetic process from serine

Molecular Function

GO:0004124 cysteine synthase activity

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.