IUBMB Enzyme Nomenclature


Accepted name: 15-cis-phytoene synthase

Reaction: 2 geranylgeranyl diphosphate = 15-cis-phytoene + 2 diphosphate (overall reaction)
(1a) 2 geranylgeranyl diphosphate = diphosphate + prephytoene diphosphate
(1b) prephytoene diphosphate = 15-cis-phytoene + diphosphate

For diagram of reaction click here

Other name(s): PSY (gene name); crtB (gene name); prephytoene-diphosphate synthase; phytoene synthetase; PSase; geranylgeranyl-diphosphate geranylgeranyltransferase

Systematic name: geranylgeranyl-diphosphate:geranylgeranyl-diphosphate geranylgeranyltransferase (15-cis-phytoene forming)

Comments: Requires Mn2+ for activity. The enzyme condenses two molecules of geranylgeranyl diphosphate to give prephytoene diphosphate, followed by rearrangement of the cyclopropylcarbinyl intermediate to 15-cis-phytoene.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 50936-61-3


1. Chamovitz, D., Misawa, N., Sandmann, G. and Hirschberg, J. Molecular cloning and expression in Escherichia coli of a cyanobacterial gene coding for phytoene synthase, a carotenoid biosynthesis enzyme. FEBS Lett. 296 (1992) 305-310. [PMID: 1537409]

2. Sandmann, G. and Misawa, N. New functional assignment of the carotenogenic genes crtB and crtE with constructs of these genes from Erwinia species. FEMS Microbiol. Lett. 69 (1992) 253-257. [PMID: 1555761]

3. Scolnik, P.A. and Bartley, G.E. Nucleotide sequence of an Arabidopsis cDNA for phytoene synthase. Plant Physiol. 104 (1994) 1471-1472. [PMID: 8016277]

4. Misawa, N., Truesdale, M.R., Sandmann, G., Fraser, P.D., Bird, C., Schuch, W. and Bramley, P.M. Expression of a tomato cDNA coding for phytoene synthase in Escherichia coli, phytoene formation in vivo and in vitro, and functional analysis of the various truncated gene products. J. Biochem. (Tokyo) 116 (1994) 980-985. [PMID: 7896759]

5. Schledz, M., al-Babili, S., von Lintig, J., Haubruck, H., Rabbani, S., Kleinig, H. and Beyer, P. Phytoene synthase from Narcissus pseudonarcissus: functional expression, galactolipid requirement, topological distribution in chromoplasts and induction during flowering. Plant J. 10 (1996) 781-792. [PMID: 8953242]

[EC created 1984, modified 2005, modified 2012]

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