Induction of phytoalexin synthesis in soybean. Stereospecific 3,9-dihydroxypterocarpan 6a-hydroxylase from elicitor-induced soybean cell cultures.
A microsomal preparation from elicitor-challenged soybean cell suspension cultures catalyzes an NADPH-dependent and dioxygen-dependent 6a-hydroxylation of 3,9-dihydroxypterocarpan to 3,6a,9-trihydroxypterocarpan. The latter is a precursor for the soybean phytoalexin glyceollin. No reaction is observed with NADH. The 6a-hydroxylase is inhibited by cytochrome c. Optical rotatory dispersion spectra of the enzymatic product formed from racemic dihydroxypterocarpan and of the remaining unreacted substrate proved that the product has the natural (6aS, 11aS)-configuration and that hydroxylation proceeds with retention of configuration. The 6a-hydroxylase was also found in elicitor-challenged soybean seedlings. The results indicate that the 6a-hydroxylase is specifically involved in the biosynthesis of glyceollin.
D001578:Benzopyrans / Q000096:biosynthesis* / Q000378:metabolism; D002478:Cells, Cultured; D002855:Chromatography, Thin Layer; D003470:Culture Media; D003577:Cytochrome P-450 Enzyme System; D004790:Enzyme Induction; D006863:Hydrogen-Ion Concentration; D006899:Mixed Function Oxygenases / Q000096:biosynthesis* / Q000378:metabolism; D010936:Plant Extracts; D010940:Plant Proteins / Q000096:biosynthesis*; D036343:Pterocarpans; D012717:Sesquiterpenes; D030262:Soybean Proteins; D013025:Glycine max / Q000201:enzymology / Q000378:metabolism*; D013237:Stereoisomerism; D013729:Terpenes; D000094162:Phytoalexins
D001578:Benzopyrans; D003470:Culture Media; D010936:Plant Extracts; D010940:Plant Proteins; D036343:Pterocarpans; D012717:Sesquiterpenes; D030262:Soybean Proteins; D013729:Terpenes; C042060:3,9-dihydroxypterocarpan; C017343:glyceollin; C042061:3,6,9-trihydroxypterocarpan; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; C042062:cytochrome P450 CYP93A1 (Glycine max); D000094162:Phytoalexins