title: A photoaffinity probe designed for host-specific signal flavonoid receptors in phytopathogenic Peronosporomycete zoospores of Aphanomyces cochlioides.
abstract: Aphanomyces cochlioides zoospores show chemotaxis to cochliophilin A (5-hydroxy-6,7-methylenedioxyflavone, 1), a host derived attractant, and also respond to 5,7-dihydroxyflavone (2) known as an equivalent chemoattractant. To investigate the chemotactic receptors in the zoospores, we designed photoaffinity probes 4'-azido-5,7-dihydroxyflavone (3) and 4'-azido-7-O-biotinyl-5-hydroxyflavone (4) considering chemical structure of 2. Both 3 and 4 had zoospore attractant activity which was competitive with that of 1. When zoospores were treated with the biotinylated photoaffinity probe followed by UV irradiation and streptavidin-gold or peroxidase-conjugated streptavidin, probe-labeled proteins were detected on the cell membrane. This result indicated that the 1-specific-binding proteins, a candidate for hypothetical cochliophilin A receptor, were localized on the cell membrane of the zoospores. This is the first experimental evidence of flavonoid-binding proteins being present in zoospores, using chemically synthesized azidoflavone as photoaffinity-labeling reagent.
authors.affiliation: Laboratory of Ecological Chemistry, Graduate School of Agriculture, Hokkaido University, Kita-ku, Sapporo 060-8589, Japan.
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Sakihama
authors.forename: Takashi
authors.initials: T
authors.lastname: Shimai
authors.forename: Mitsuyoshi
authors.initials: M
authors.lastname: Sakasai
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Ito
authors.forename: Yukiharu
authors.initials: Y
authors.lastname: Fukushi
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Hashidoko
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tahara
mesh_terms: D044744:Aphanomyces / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure*; D002478:Cells, Cultured; D002633:Chemotaxis / Q000187:drug effects / Q000502:physiology*; D047309:Flavones / Q000378:metabolism* / Q000494:pharmacology*; D044742:Peronospora / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure*; D019920:Photoaffinity Labels; D011956:Receptors, Cell Surface / Q000378:metabolism*; D013045:Species Specificity; D013170:Spores / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure*
chemical_list: D047309:Flavones; D019920:Photoaffinity Labels; D011956:Receptors, Cell Surface; C494663:cochliophilin A