Shin-ichi Ayabe

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Leguminous plants produce 5-deoxyflavonoids and 5-deoxyisoflavonoids that play essential roles in legume-microbe interactions. Together with chalcone polyketide reductase and cytochrome P450 2-hydroxyisoflavanone synthase, the chalcone isomerase (CHI) of leguminous plants is fundamental in the construction of these ecophysiologically active flavonoids.(More)
Isoflavonoids are distributed predominantly in leguminous plants and play critical roles in plant physiology. A cytochrome P450 (P450), 2-hydroxyisoflavanone synthase, is the key enzyme in their biosynthesis. In cultured licorice (Glycyrrhiza echinata L., Fabaceae) cells, the production of both an isoflavonoid-derived phytoalexin (medicarpin) and a(More)
Formononetin (7-hydroxy-4'-methoxyisoflavone, also known as 4'-O-methyldaidzein) is an essential intermediate of ecophysiologically active leguminous isoflavonoids. The biosynthetic pathway to produce 4'-methoxyl of formononetin has been unknown because the methyl transfer from S-adenosyl-L-methionine (SAM) to 4'-hydroxyl of daidzein has never been detected(More)
The microsome of insect cells expressing CYP Ge-5 (CYP93B1), a cytochrome P450 cDNA of licorice (Glycyrrhiza echinata L.), catalyzed the formation of [14C]licodione and [14C]2-hydroxynaringenin from (2S)-[14C]liquiritigenin and (2S)-[14C]naringenin, respectively. On acid treatment, the products were converted to 14C-labeled 7,4'-dihydroxyflavone and(More)
Glyceollins are soybean (Glycine max) phytoalexins possessing pterocarpanoid skeletons with cyclic ether decoration originating from a C5 prenyl moiety. Enzymes involved in glyceollin biosynthesis have been thoroughly characterized during the early era of modern plant biochemistry, and many genes encoding enzymes of isoflavonoid biosynthesis have been(More)
The microsome of yeast cells overexpressing CYP81E1, a cytochrome P450 cDNA recently cloned from licorice (Glycyrrhiza echinata L., Fabaceae), catalyzed the hydroxylation of isoflavones, daidzein and formononetin, to yield 2'-hydroxyisoflavones, 2'-hydroxydaidzein, and 2'-hydroxyformononetin, respectively. The chemical structures of the reaction products(More)
Isoflavans and pterocarpans are the major biosynthetically connected phytoalexins in legumes. A search of the expressed sequence tag library of a model legume Lotus japonicus, which produces an (-)-isoflavan, for homologs of phenylcoumaran benzylic ether reductase catalyzing the reductive cleavage of dihydrofurans, yielded seven full-length cDNAs, and the(More)
Glycyrrhiza echinata cell-free extract produced isoformononetin by the 7-O-transmethylation of daidzein from S-adenosyl-L-methionine (SAM). When the yeast microsome expressing 2-hydroxyisoflavanone synthase was mixed with the cell-free extract and incubated with liquiritigenin and SAM, formononetin emerged. Furthermore, the cell-free extract yielded(More)
Isoflavonoids are distributed predominantly in leguminous plants, and play pivotal roles in the interaction of host plants with biological environments. Isoflavones in the diet also have beneficial effects on human health as phytoestrogens. The isoflavonoid skeleton is constructed by the CYP93C subfamily of cytochrome P450s in plant cells. The reaction(More)
Many soil bacteria contain 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, which degrades ACC, a precursor of the phytohormone ethylene. In order to examine the regulation of the acdS gene encoding ACC deaminase in Mesorhizobium loti MAFF303099 during symbiosis with the host legume Lotus japonicus, we introduced the beta-glucuronidase (GUS) gene into(More)