title: Escherichia coli as a platform for functional expression of plant P450 carotene hydroxylases.
abstract: Carotenoids and their derivatives are essential for growth, development, and signaling in plants and have an added benefit as nutraceuticals in food crops. Despite the importance of the biosynthetic pathway, there remain open questions regarding some of the later enzymes in the pathway. The CYP97 family of P450 enzymes was predicted to function in carotene ring hydroxylation, to convert provitamin A carotenes to non-provitamin A xanthophylls. However, substrate specificity was difficult to investigate directly in plants, which mask enzyme activities by a complex and dynamic metabolic network. To characterize the enzymes more directly, we amplified cDNAs from a model crop, Oryza sativa, and used functional complementation in Escherichia coli to test activity and specificity of members of Clans A and C. This heterologous system will be valuable for further study of enzyme interactions and substrate utilization needed to understand better the role of CYP97 hydroxylases in plant carotenoid biosynthesis.
authors.affiliation: Department of Biological Sciences, Lehman College, The City University of New York, 250 Bedford Park Boulevard West, Bronx, NY 10468, USA.
authors.forename: Rena F
authors.initials: RF
authors.lastname: Quinlan
authors.forename: Tahhan T
authors.initials: TT
authors.lastname: Jaradat
authors.forename: Eleanore T
authors.initials: ET
authors.lastname: Wurtzel
mesh_terms: D000595:Amino Acid Sequence; D002338:Carotenoids / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics*; D017343:Genes, Plant; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics; D010944:Plants / Q000201:enzymology* / Q000235:genetics; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000378:metabolism; D017422:Sequence Analysis, DNA; D013379:Substrate Specificity; D014169:Transformation, Bacterial
chemical_list: D010940:Plant Proteins; D011994:Recombinant Proteins; D002338:Carotenoids; D003577:Cytochrome P-450 Enzyme System