title: Cloning and characterization of a human beta,beta-carotene-15,15'-dioxygenase that is highly expressed in the retinal pigment epithelium.
abstract: Retinoids play a critical role in vision, as well as in development and cellular differentiation. beta,beta-Carotene-15,15'-dioxygenase (Bcdo), the enzyme that catalyzes the oxidative cleavage of beta,beta-carotene into two retinal molecules, plays an important role in retinoid synthesis. We report here the first cloning of a mammalian Bcdo. Human BCDO encodes a protein of 547 amino acid residues that demonstrates 68% identity with chicken Bcdo. It is expressed highly in the retinal pigment epithelium (RPE) and also in kidney, intestine, liver, brain, stomach, and testis. The gene spans approximately 20 kb, is composed of 11 exons and 10 introns, and maps to chromosome 16q21-q23. A mouse orthologue was also identified, and its predicted amino acid sequence is 83% identical with human BCDO. Biochemical analysis of baculovirus expressed human BCDO demonstrates the predicted beta,beta-carotene-15,15'-dioxygenase activity. The expression pattern of BCDO suggests that it may provide a local supplement to the retinoids available to photoreceptors, as well as a supplement to the retinoid pools utilized elsewhere in the body. In addition, the finding that many of the enzymes involved in retinoid metabolism are mutated in retinal degenerations suggests that BCDO may also be a candidate gene for retinal degenerative disease.
authors.affiliation: Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, Maryland, 21287, USA.
authors.forename: W
authors.initials: W
authors.lastname: Yan
authors.forename: G F
authors.initials: GF
authors.lastname: Jang
authors.forename: F
authors.initials: F
authors.lastname: Haeseleer
authors.forename: N
authors.initials: N
authors.lastname: Esumi
authors.forename: J
authors.initials: J
authors.lastname: Chang
authors.forename: M
authors.initials: M
authors.lastname: Kerrigan
authors.forename: M
authors.initials: M
authors.lastname: Campochiaro
authors.forename: P
authors.initials: P
authors.lastname: Campochiaro
authors.forename: K
authors.initials: K
authors.lastname: Palczewski
authors.forename: D J
authors.initials: DJ
authors.lastname: Zack
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D002460:Cell Line; D002874:Chromosome Mapping; D002885:Chromosomes, Human, Pair 16; D003001:Cloning, Molecular; D018076:DNA, Complementary; D015870:Gene Expression; D006801:Humans; D007313:Insecta; D008027:Light; D051379:Mice; D008969:Molecular Sequence Data; D010105:Oxygenases / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D010857:Pigment Epithelium of Eye / Q000201:enzymology*; D012333:RNA, Messenger / Q000096:biosynthesis; D017386:Sequence Homology, Amino Acid; D014212:Tretinoin / Q000378:metabolism; D050559:beta-Carotene 15,15'-Monooxygenase
chemical_list: D018076:DNA, Complementary; D012333:RNA, Messenger; D014212:Tretinoin; D010105:Oxygenases; C493359:Bco1 protein, mouse; C493358:BCO1 protein, human; D050559:beta-Carotene 15,15'-Monooxygenase