Phytoene desaturase (lycopene-forming) (CrtI, four-step phytoene desaturase) (EC 1.3.99.31, 15-cis-phytoene:acceptor oxidoreductase (lycopene-forming)) are enzymes found in archaea, bacteria and fungi that are involved in carotenoid biosynthesis.[2] 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.[3]
Phytoene desaturase (lycopene-forming) | |||||||||
---|---|---|---|---|---|---|---|---|---|
Identifiers | |||||||||
EC no. | 1.3.99.31 | ||||||||
Databases | |||||||||
IntEnz | IntEnz view | ||||||||
BRENDA | BRENDA entry | ||||||||
ExPASy | NiceZyme view | ||||||||
KEGG | KEGG entry | ||||||||
MetaCyc | metabolic pathway | ||||||||
PRIAM | profile | ||||||||
PDB structures | RCSB PDB PDBe PDBsum | ||||||||
|
Bacterial phytoene desaturases were shown to require FAD as a cofactor for their function.[4] During the chemical reaction in total four additional double bonds are introduced into phytoene:
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.[5] This approach was later used in rice to increase its β-carotene content resulting in the Golden Rice project.