title: On the substrate- and stereospecificity of the plant carotenoid cleavage dioxygenase 7.
abstract: Strigolactones are phytohormones synthesized from carotenoids via a stereospecific pathway involving the carotenoid cleavage dioxygenases 7 (CCD7) and 8. CCD7 cleaves 9-cis-β-carotene to form a supposedly 9-cis-configured β-apo-10'-carotenal. CCD8 converts this intermediate through a combination of yet undetermined reactions into the strigolactone-like compound carlactone. Here, we investigated the substrate and stereo-specificity of the Arabidopsis and pea CCD7 and determined the stereo-configuration of the β-apo-10'-carotenal intermediate by using Nuclear Magnetic Resonance Spectroscopy. Our data unequivocally demonstrate the 9-cis-configuration of the intermediate. Both CCD7s cleave different 9-cis-carotenoids, yielding hydroxylated 9-cis-apo-10'-carotenals that may lead to hydroxylated carlactones, but show highest affinity for 9-cis-β-carotene.
authors.affiliation: Albert-Ludwigs University of Freiburg, Faculty of Biology, Schaenzlestr. 1, D-79104 Freiburg, Germany.
authors.forename: Mark
authors.initials: M
authors.lastname: Bruno
authors.affiliation: Albert-Ludwigs University of Freiburg, Faculty of Biology, Schaenzlestr. 1, D-79104 Freiburg, Germany.
authors.forename: Manuel
authors.initials: M
authors.lastname: Hofmann
authors.affiliation: Department of Chemistry and Biochemistry, University of Bern, 3012 Bern, Switzerland.
authors.forename: Martina
authors.initials: M
authors.lastname: Vermathen
authors.affiliation: Albert-Ludwigs University of Freiburg, Faculty of Biology, Schaenzlestr. 1, D-79104 Freiburg, Germany.
authors.forename: Adrian
authors.initials: A
authors.lastname: Alder
authors.affiliation: Albert-Ludwigs University of Freiburg, Faculty of Biology, Schaenzlestr. 1, D-79104 Freiburg, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Beyer
authors.affiliation: Albert-Ludwigs University of Freiburg, Faculty of Biology, Schaenzlestr. 1, D-79104 Freiburg, Germany; Center for Desert Agriculture, BESE Division, King Abdullah University of Science and Technology (KAUST), 23955-6900 Thuwal, Saudi Arabia. Electronic address: salim.babili@kaust.edu.sa.
authors.forename: Salim
authors.initials: S
authors.lastname: Al-Babili
mesh_terms: D017360:Arabidopsis / Q000201:enzymology*; D029681:Arabidopsis Proteins; D002338:Carotenoids / Q000737:chemistry; D049308:Dioxygenases / Q000737:chemistry*; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D018532:Pisum sativum / Q000201:enzymology*; D013237:Stereoisomerism; D013379:Substrate Specificity
chemical_list: D029681:Arabidopsis Proteins; D002338:Carotenoids; C494441:CCD7 protein, Arabidopsis; D049308:Dioxygenases
keywords: Apocarotenoid; Carlactone; Carotenoid; Carotenoid cleavage dioxygenase; Strigolactone