EC - S-sulfo-L-cysteine synthase (O-acetyl-L-serine-dependent)

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IntEnz Enzyme Nomenclature


Accepted name:
S-sulfo-L-cysteine synthase (O-acetyl-L-serine-dependent)
Other names:
cysteine synthase B
cysM (gene name)
CS26 (gene name)
Systematic name:
O-acetyl-L-serine:thiosulfate 2-amino-2-carboxyethyltransferase



In plants, the activity is catalysed by a chloroplastic enzyme that plays an important role in chloroplast function and is essential for light-dependent redox regulation within the chloroplast. The bacterial enzyme also catalyses the activity of EC, cysteine synthase. cf. EC, S-sulfo-L-cysteine synthase (3-phospho-L-serine-dependent).

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Structural data: CSA , EC2PDB


  1. Hensel, G., Truper, H. G.
    O-Acetylserine sulfhydrylase and S-sulfocysteine synthase activities of Rhodospirillum tenue.
    Arch. Microbiol. 134: 227-232 (1983). [PMID: 6615127]
  2. Nakamura, T., Iwahashi, H., Eguchi, Y.
    Enzymatic proof for the identity of the S-sulfocysteine synthase and cysteine synthase B of Salmonella typhimurium.
    J. Bacteriol. 158: 1122-1127 (1984). [PMID: 6373737]
  3. Bermudez, M. A., Paez-Ochoa, M. A., Gotor, C., Romero, L. C.
    Arabidopsis S-sulfocysteine synthase activity is essential for chloroplast function and long-day light-dependent redox control.
    Plant Cell 22: 403-416 (2010). [PMID: 20179139]
  4. Bermudez, M. A., Galmes, J., Moreno, I., Mullineaux, P. M., Gotor, C., Romero, L. C.
    Photosynthetic adaptation to length of day is dependent on S-sulfocysteine synthase activity in the thylakoid lumen.
    Plant Physiol. 160: 274-288 (2012). [PMID: 22829322]
  5. Gotor, C., Romero, L. C.
    S-sulfocysteine synthase function in sensing chloroplast redox status.
    Plant Signal Behav. 8: e23313 (2013). [PMID: 23333972]

[EC created 2018]