title: Possible involvement of a tetrahydrobiopterin in photoreception for UV-B-induced anthocyanin synthesis in carrot.
abstract: Our previous studies of action spectra for UV-B-induced anthocyanin accumulation in cultured carrot cells indicated that a reduced form of pterin, possibly tetrahydrobiopterin, contributes to UV-B photoreception. In this report, we provide additional evidence for the involvement of pterin in UV-B light sensing. UV-B-induced phenylalanine ammonia-lyase (PAL) activity was considerably suppressed by N-acetylserotonin (an inhibitor of tetrahydrobiopterin biosynthesis), and this suppression was partially recovered by adding biopterin or tetrahydrobiobiopterin. In addition, protein(s) specifically bound to biopterin were detected by radiolabeling experiments in N-acetylserotonin-treated cells. Furthermore, diphenyleneiodonium, a potent inhibitor of electron transfer, completely suppressed UV-B-induced PAL activity. These results suggest the occurrence of an unidentified UV-B photoreceptor (other than UVR8, the tryptophan-based UV-B sensor originally identified in Arabidopsis) with reduced pterin in carrot cells. After reexamining published action spectra, we suggest that anthocyanin synthesis is coordinately regulated by these two UV-B sensors.
authors.affiliation: Laboratory of Applied Microbiology and Biochemistry, Nara Women's University, Nara, Japan.
authors.forename: Junko
authors.initials: J
authors.lastname: Takeda
authors.forename: Rieko
authors.initials: R
authors.lastname: Nakata
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ueno
authors.forename: Akio
authors.initials: A
authors.lastname: Murakami
authors.forename: Mineo
authors.initials: M
authors.lastname: Iseki
authors.forename: Masakatsu
authors.initials: M
authors.lastname: Watanabe
mesh_terms: D000872:Anthocyanins / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D001708:Biopterins / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000378:metabolism / Q000494:pharmacology; D018552:Daucus carota / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects*; D004579:Electron Transport / Q000187:drug effects / Q000528:radiation effects; D004583:Electrons; D009861:Onium Compounds / Q000494:pharmacology; D010084:Oxidation-Reduction; D010650:Phenylalanine Ammonia-Lyase / Q000037:antagonists & inhibitors / Q000378:metabolism; D055668:Photochemical Processes; D010940:Plant Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012701:Serotonin / Q000031:analogs & derivatives / Q000494:pharmacology; D014466:Ultraviolet Rays
chemical_list: D000872:Anthocyanins; D009861:Onium Compounds; D010940:Plant Proteins; D001708:Biopterins; D012701:Serotonin; C007517:diphenyleneiodonium; D010650:Phenylalanine Ammonia-Lyase; C003402:sapropterin; C006389:N-acetylserotonin