Phytoene desaturase (lycopene-forming)
Template:Infobox enzyme Phytoene desaturase (lycopene-forming) (CrtI, four-step phytoene desaturase) (Template:EC number, 15-cis-phytoene:acceptor oxidoreductase (lycopene-forming)) are enzymes found in archaea, bacteria and fungi that are involved in carotenoid biosynthesis.[1] They catalyze the conversion of colorless 15-cis-phytoene into a bright red lycopene in a biochemical pathway called the poly-trans pathway. The same process in plants and cyanobacteria utilizes four separate enzymes in a poly-cis pathway.[2]
Biochemistry
Bacterial phytoene desaturases were shown to require FAD as a cofactor for their function.[3] During the chemical reaction in total four additional double bonds are introduced into phytoene:
- 15-cis-phytoene + 4 acceptor all-trans-lycopene + 4 reduced acceptor (overall reaction)
- (1a) 15-cis-phytoene + acceptor all-trans-phytofluene + reduced acceptor
- (1b) all-trans-phytofluene + acceptor all-trans-zeta-carotene + reduced acceptor
- (1c) all-trans-zeta-carotene + acceptor all-trans-neurosporene + reduced acceptor:
- (1d) all-trans-neurosporene + acceptor all-trans-lycopene + reduced acceptor
Applications
In 2000 it was discovered that the gene insertion of a bacterial phytoene desaturase into transgenic tomatoes increased the lycopene content without the need to alter several of the plants enzymes.[4] This approach was later used in rice to increase its β-carotene content resulting in the Golden Rice project.
See also
- 15-''Cis''-phytoene desaturase
- Phytoene desaturase (neurosporene-forming)
- Phytoene desaturase (zeta-carotene-forming)
- Phytoene desaturase (3,4-didehydrolycopene-forming)
References
External links
Template:CH-CH oxidoreductases Template:Enzymes Template:Portal bar