IUBMB Enzyme Nomenclature


Accepted name: carlactone synthase

Reaction: 9-cis-10'-apo-β-carotenal + 2 O2 = carlactone + (2E,4E,6E)-7-hydroxy-4-methylhepta-2,4,6-trienal

For diagram of reaction click here and mechanism click here.

Glossary: carlactone = 3-methyl-5-{[(1Z,3E)-2-methyl-4-(2,6,6-trimethylcyclohex-1-en-1-yl)buta-1,3-dien-1-yl]oxy}-5H-furan-2-one

Other name(s): CCD8 (gene name); MAX4 (gene name); NCED8 (gene name); 9-cis-10'-apo-β-carotenal:O2 oxidoreductase (14,15-cleaving, carlactone-forming)

Systematic name: 9-cis-10'-apo-β-carotenal:oxygen oxidoreductase (14,15-cleaving, carlactone-forming)

Comments: Requires Fe2+. The enzyme participates in a pathway leading to biosynthesis of strigolactones, plant hormones involved in promotion of symbiotic associations known as arbuscular mycorrhiza. Also catalyses EC, all-trans-10'-apo-β-carotenal 13,14-cleaving dioxygenase, but 10-fold slower. The secondary product has not been characterized, but may be (2E,4E,6E)-7-hydroxy-4-methylhepta-2,4,6-trienal or one of its tautomers. The preferred tautomeric form is not known.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:


1. Sorefan, K., Booker, J., Haurogne, K., Goussot, M., Bainbridge, K., Foo, E., Chatfield, S., Ward, S., Beveridge, C., Rameau, C. and Leyser, O. MAX4 and RMS1 are orthologous dioxygenase-like genes that regulate shoot branching in Arabidopsis and pea. Genes Dev. 17 (2003) 1469-1474. [PMID: 12815068]

2. Schwartz, S.H., Qin, X. and Loewen, M.C. The biochemical characterization of two carotenoid cleavage enzymes from Arabidopsis indicates that a carotenoid-derived compound inhibits lateral branching. J. Biol. Chem. 279 (2004) 46940-46945. [PMID: 15342640]

3. Alder, A., Jamil, M., Marzorati, M., Bruno, M., Vermathen, M., Bigler, P., Ghisla, S., Bouwmeester, H., Beyer, P. and Al-Babili, S. The path from β-carotene to carlactone, a strigolactone-like plant hormone. Science 335 (2012) 1348-1351. [PMID: 22422982]

[EC created 2012]

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