crtS (gene name);
crtW (gene name)
Acting on paired donors, with incorporation or reduction of molecular oxygen;
beta-carotene,donor:oxygen oxidoreductase (echinenone-forming)
(1) beta-carotene + 2 reduced acceptor + 2 O2 = echinenone + 2 acceptor + 3 H2O [RN:
(2) echinenone + 2 reduced acceptor + 2 O2 = canthaxanthin + 2 acceptor + 3 H2O [RN:
The enzyme, studied from algae, plants, fungi, and bacteria, adds an oxo group at position 4 of a carotenoid beta ring. It is involved in the biosynthesis of carotenoids such as astaxanthin and flexixanthin. The enzyme does not act on beta rings that are hydroxylated at position 3, such as in zeaxanthin (cf. EC
, zeaxanthin 4-ketolase). The enzyme from the yeast Xanthophyllomyces dendrorhous is bifuntional and also catalyses the activity of EC
, beta-carotene 3-hydroxylase.
EC 18.104.22.168 created 2018
ec01110 Biosynthesis of secondary metabolites
K09836 beta-carotene/zeaxanthin 4-ketolase
K23037 beta-carotene 4-ketolase/3-hydroxylase
CMP: Cha6605_0315 Cha6605_4514 Cha6605_5744
GLP: Glo7428_2965 Glo7428_3135
NPU: Npun_F4798 Npun_F5919
ANN: EH233_18150 EH233_26505
TOQ: HCG51_00755 HCG51_17065 » show all
Lotan T, Hirschberg J
Cloning and expression in Escherichia coli of the gene encoding beta-C-4-oxygenase, that converts beta-carotene to the ketocarotenoid canthaxanthin in Haematococcus pluvialis.
Breitenbach J, Misawa N, Kajiwara S, Sandmann G
Expression in Escherichia coli and properties of the carotene ketolase from Haematococcus pluvialis.
Steiger S, Sandmann G
Cloning of two carotenoid ketolase genes from Nostoc punctiforme for the heterologous production of canthaxanthin and astaxanthin.
Ojima K, Breitenbach J, Visser H, Setoguchi Y, Tabata K, Hoshino T, van den Berg J, Sandmann G
Cloning of the astaxanthin synthase gene from Xanthophyllomyces dendrorhous (Phaffia rhodozyma) and its assignment as a beta-carotene 3-hydroxylase/4-ketolase.
Tao L, Yao H, Kasai H, Misawa N, Cheng Q
A carotenoid synthesis gene cluster from Algoriphagus sp. KK10202C with a novel fusion-type lycopene beta-cyclase gene.
Kathiresan S, Chandrashekar A, Ravishankar GA, Sarada R
Regulation of astaxanthin and its intermediates through cloning and genetic transformation of beta-carotene ketolase in Haematococcus pluvialis.