Induction of two prenyltransferases for the accumulation of coumarin phytoalexins in elicitor-treated Ammi majus cell suspension cultures.
Two dimethylallyl diphosphate:umbelliferone dimethylallyltransferase (prenyltransferase) activities, catalysing the 6-prenylation and the 7-O-prenylation, respectively, of umbelliferone in the course of phytoalexin synthesis, increased in Ammi majus cell suspension cultures in response to elicitor treatment. Both enzyme activities were dependent on Mg2+ or Mn2+ with significant preference for Mg2+ in the 6-prenylation reaction. Whereas dark-grown cells did not contain these activities, both prenyltransferase activities were induced rapidly by the addition of elicitor reaching a first maximum after 10-14 hr and a second maximum beyond 30 hr. Other coumarin specific, elicitor-induced enzyme activities of A. majus cells, in contrast, showed only one maximum of activity within the 50 hr experimental period, while the pattern of induction of phenylalanine ammonia-lyase activity resembled that of the prenyltransferases with maxima at ca 8 hr and 20-30 hr. Preliminary data suggest that the apparent biphasic induction of these enzyme activities is due to post-translational enzyme modifications.
Department of Plant Biochemistry, University of Freiburg, F.R.G.
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Hamerski
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Schmitt
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Matern
D019883:Alkyl and Aryl Transferases; D002478:Cells, Cultured; D003374:Coumarins / Q000378:metabolism*; D004122:Dimethylallyltranstransferase / Q000096:biosynthesis*; D004790:Enzyme Induction; D007700:Kinetics; D008274:Magnesium / Q000378:metabolism; D008345:Manganese / Q000378:metabolism; D008861:Microsomes / Q000201:enzymology; D010650:Phenylalanine Ammonia-Lyase / Q000096:biosynthesis; D010838:Phytophthora; D010936:Plant Extracts / Q000096:biosynthesis*; D010944:Plants / Q000201:enzymology* / Q000378:metabolism; D012717:Sesquiterpenes; D013379:Substrate Specificity; D013729:Terpenes; D014166:Transferases / Q000096:biosynthesis*; D014468:Umbelliferones / Q000378:metabolism; D000094162:Phytoalexins
D003374:Coumarins; D010936:Plant Extracts; D012717:Sesquiterpenes; D013729:Terpenes; D014468:Umbelliferones; D008345:Manganese; C031477:7-hydroxycoumarin; D014166:Transferases; D019883:Alkyl and Aryl Transferases; C065121:dimethylallyl diphosphate umbelliferone 7-O-dimethyltransferase; C065120:dimethylallyl diphosphate-umbelliferone 6-dimethyltransferase; D004122:Dimethylallyltranstransferase; D010650:Phenylalanine Ammonia-Lyase; D008274:Magnesium; D000094162:Phytoalexins