title: Carotenoid β-ring hydroxylase and ketolase from marine bacteria-promiscuous enzymes for synthesizing functional xanthophylls.
abstract: Marine bacteria belonging to genera Paracoccus and Brevundimonas of the α-Proteobacteria class can produce C₄₀-type dicyclic carotenoids containing two β-end groups (β rings) that are modified with keto and hydroxyl groups. These bacteria produce astaxanthin, adonixanthin, and their derivatives, which are ketolated by carotenoid β-ring 4(4')-ketolase (4(4')-oxygenase; CrtW) and hydroxylated by carotenoid β-ring 3(3')-hydroxylase (CrtZ). In addition, the genus Brevundimonas possesses a gene for carotenoid β-ring 2(2')-hydroxylase (CrtG). This review focuses on these carotenoid β-ring-modifying enzymes that are promiscuous for carotenoid substrates, and pathway engineering for the production of xanthophylls (oxygen-containing carotenoids) in Escherichia coli, using these enzyme genes. Such pathway engineering researches are performed towards efficient production not only of commercially important xanthophylls such as astaxanthin, but also of xanthophylls minor in nature (e.g., β-ring(s)-2(2')-hydroxylated carotenoids).
authors.affiliation: Research Institute for Bioresources and Biotechnology, Ishikawa Prefectural University, Suematsu, Nonoichi-machi, Ishikawa 921-8836, Japan.
authors.forename: Norihiko
authors.initials: N
authors.lastname: Misawa
mesh_terms: D020561:Alphaproteobacteria / Q000201:enzymology* / Q000235:genetics; D005818:Genetic Engineering; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000378:metabolism*; D010105:Oxygenases / Q000235:genetics / Q000378:metabolism*; D014871:Water Microbiology; D024341:Xanthophylls / Q000096:biosynthesis*
chemical_list: D024341:Xanthophylls; D006899:Mixed Function Oxygenases; D010105:Oxygenases; C093259:beta-carotene ketolase; C079232:beta-carotene hydroxylase