title: A crtA-related gene from Flavobacterium P99-3 encodes a novel carotenoid 2-hydroxylase involved in myxol biosynthesis.
abstract: A genomic DNA fragment with carotenogenic genes involved in myxol biosynthesis (3',4'-didehydro-1',2'-dihydro-beta,psi-carotene-3,1',2'-triol) was cloned from Flavobacterium P99-3. It contains a gene highly homologous to crtA from purple bacteria encoding there an acyclic carotenoid 2-ketolase. Since no ketolation step is involved in myxol biosynthesis, the function of crtA-OH from Flavobacterium was assigned by complementation in Escherichia coli engineered to synthesize demethylspheroidene and 1'-hydroxy-demethylspheroidene. Upon co-expression of crtA-OH, the formation of 2-hydroxy derivatives of both carotenoids assigns CrtA-OH as a novel carotenoid hydroxylase. The gene was used to re-construct myxol biosynthesis in E. coli successfully. Additionally, 1',2'-dihydroxytorulene and 1,2,1'-trihydroxy-3,4,3',4'-tetradehydrolycopene were obtained. Their generation demonstrates that a new class of 2-hydroxy carotenoids can now be pursued by genetic engineering in E. coli.
authors.affiliation: Biosynthesis Group, Molecular Biosciences 213, Department of Biological Sciences, J.W. Goethe Universität, Frankfurt, Germany.
authors.forename: Nina
authors.initials: N
authors.lastname: Rählert
authors.forename: Paul D
authors.initials: PD
authors.lastname: Fraser
authors.forename: Gerhard
authors.initials: G
authors.lastname: Sandmann
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D002338:Carotenoids / Q000096:biosynthesis*; D002384:Catalysis; D004269:DNA, Bacterial / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005417:Flavobacterium / Q000201:enzymology* / Q000378:metabolism; D005798:Genes, Bacterial; D005818:Genetic Engineering; D006899:Mixed Function Oxygenases / Q000235:genetics*; D010802:Phylogeny
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; C488895:myxol; D002338:Carotenoids; D006899:Mixed Function Oxygenases; C079232:beta-carotene hydroxylase