title: Isoquinoline alkaloid biosynthesis is regulated by a unique bHLH-type transcription factor in Coptis japonica.
abstract: Specific plant species produce unique isoquinoline alkaloids (IQAs); however, the mechanism of their evolution and the regulation of their biosynthesis are largely unknown. We report here the isolation of a novel basic helix-loop-helix protein, CjbHLH1, from IQA-producing Coptis japonica. A BLAST search indicated that CjbHLH1 homologs were only found in plant species that produce IQAs. Transient RNA interference (RNAi) and overexpression of CjbHLH1 in C. japonica protoplasts revealed the activity of CjbHLH1 in transcription of IQA biosynthetic genes, and little activity in the transcription of genes involved in primary metabolism or the stress response. A chromatin immunoprecipitation experiment using CjbHLH1-specific antibodies revealed the direct interaction of CjbHLH1 with promoter sequences of IQA biosynthetic genes in vivo. We discuss the unique role of CjbHLH1 in IQA biosynthesis.
authors.affiliation: Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Yamada
authors.forename: Yasuhisa
authors.initials: Y
authors.lastname: Kokabu
authors.forename: Kaori
authors.initials: K
authors.lastname: Chaki
authors.forename: Tadashi
authors.initials: T
authors.lastname: Yoshimoto
authors.forename: Mai
authors.initials: M
authors.lastname: Ohgaki
authors.forename: Sayumi
authors.initials: S
authors.lastname: Yoshida
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Kato
authors.forename: Tomotsugu
authors.initials: T
authors.lastname: Koyama
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Sato
mesh_terms: D000470:Alkaloids / Q000096:biosynthesis*; D000595:Amino Acid Sequence; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism*; D001599:Berberine / Q000378:metabolism; D039323:Coptis / Q000235:genetics / Q000378:metabolism*; D020224:Expressed Sequence Tags; D018506:Gene Expression Regulation, Plant; D015723:Gene Library; D007546:Isoquinolines / Q000378:metabolism*; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D034622:RNA Interference; D018749:RNA, Plant / Q000235:genetics; D014158:Transcription, Genetic
chemical_list: D000470:Alkaloids; D051792:Basic Helix-Loop-Helix Proteins; D001599:Berberine; D007546:Isoquinolines; D010940:Plant Proteins; D018749:RNA, Plant