title: Structural diversity and functional novelty of new carotenoid biosynthesis genes.
abstract: Many new carotenoid synthesis genes have recently been identified through genomic sequencing or functional cloning. Some of them exhibit novel structures and/or novel functions. This review describes such examples in the families of lycopene beta-cyclases, putative homologues of phytoene dehydrogenases and new carotenoid hydroxylases. Both the functionally novel lycopene beta-monocyclases and structurally novel fusion-type of lycopene beta-cyclases were described. Another newly discovered sequence of lycopene beta-cyclase described might represent a new class of lycopene beta-cyclases previously not identified in several cyanobacteria. Three examples of putative homologues of phytoene dehydrogenases were described, however, they were confirmed to encode different and/or new functions such as beta-carotene ketolase, 4,4'-diapolycopene oxygenase or prolycopene isomerase. Two new carotenoid hydroxylase genes were described that encoded the new function of 2,2'-beta-ionone ring hydroxylase or 3,3'-isorenieratene hydroxylase. Phylogenetic analysis of these genes shed light on their possible evolutionary origins. These new genes also provide tools for synthesis of novel and desirable carotenoids by genetic engineering.
authors.affiliation: Biological and Chemical Sciences and Engineering, Central Research and Development, E. I. DuPont de Nemours Inc., Experimental Station, E328/B48, Wilmington, DE 19880-0328, USA. qiong.cheng@usa.dupont.com
authors.forename: Qiong
authors.initials: Q
authors.lastname: Cheng
mesh_terms: D001419:Bacteria / Q000201:enzymology* / Q000235:genetics*; D002338:Carotenoids / Q000096:biosynthesis*; D005798:Genes, Bacterial; D014644:Genetic Variation; D019753:Intramolecular Lyases / Q000235:genetics / Q000502:physiology; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000502:physiology; D010088:Oxidoreductases / Q000235:genetics / Q000502:physiology
chemical_list: D002338:Carotenoids; D006899:Mixed Function Oxygenases; D010088:Oxidoreductases; C079232:beta-carotene hydroxylase; C022398:phytoene dehydrogenase; D019753:Intramolecular Lyases; C070925:lycopene cyclase-isomerase