Reaction: (1) 2 geranylgeranyl diphosphate = diphosphate + prephytoene diphosphate
(2) prephytoene diphosphate = phytoene + diphosphate
For diagram click here.
Other name(s): prephytoene-diphosphate synthase; phytoene synthetase; PSase; geranylgeranyl-diphosphate geranylgeranyltransferase
Systematic name: geranylgeranyl-diphosphate:geranylgeranyl-diphosphate geranylgeranyltransferase
Comments: Requires Mn2+ for activity. The enzyme appears to be stereospecific, normally producing 15-cis-phytoene. However, in Erwinia herbicola, the product is the 15-trans isomer [2].
Links to other databases: BRENDA, EXPASY, KEGG, CAS registry number: 50936-61-3
References:
1. Gregonis, D.E. and Rilling, H.C. The stereochemistry of trans-phytoene synthesis. Some observations on lycopersene as a carotene precursor and a mechanism for the synthesis of cis- and trans-phytoene. Biochemistry 13 (1974) 1538-1542. [PMID: 4819767]
2. Iwata-Reuyl, D., Math, S.K., Desai, S.B. and Poulter, C.D. Bacterial phytoene synthase: molecular cloning, expression, and characterization of Erwinia herbicola phytoene synthase. Biochemistry 42 (2003) 3359-3365. [PMID: 12641468]
3. 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]