tailieunhanh - Báo cáo Y học: Molecular cloning and characterization of isomultiflorenol synthase, a new triterpene synthase from Luffa cylindrica, involved in biosynthesis of bryonolic acid

An oxidosqualene cyclase cDNA, LcIMS1, was isolated from cultured cells of Luffa cylindrica Roem. by heterologous hybridization with cDNA of Glycyrrhiza glabra b-amyrin synthase. Expression of LcIMS1 in yeast lacking endogenous oxidosqualene cyclase activity resulted in the accumulation of isomultiflorenol, a triterpene. This is consistent with LcIMS1 encoding isomultiflorenol synthase, an oxidosqualene cyclase involved in bryonolic acid biosynthesis in cultured Luffa cells. The deduced aminoacid sequence of LcIMS1 shows relatively low identity with other triterpene synthases, suggesting that isomultiflorenol synthase should be classified into a new group of triterpene synthases. . | Eur. J. Biochem. 268 6311-6317 2001 FEBS 2001 Molecular cloning and characterization of isomultiflorenol synthase a new triterpene synthase from Luffa cylindrica involved in biosynthesis of bryonolic acid Hiroaki Havashi1. Penavu Huana1. Kenichiro Inoue1 Noboru Hiraoka2 Yasumasa Ikeshiro2. Kazufumi Yazaki3 Shigeo Tanaka4 Tetsuo Kushiro5 Masaaki Shibuya5 and Yutaka Ebizuka5 1Gifu Pharmaceutical University Japan 2Niigata College of Pharmacy Japan 3Graduate School of Biostudies Kyoto University Japan Graduate School of Pharmaceutical Sciences Kyoto University Japan 5Graduate School of Pharmaceutical Sciences University of Tokyo Japan An oxidosqualene cyclase cDNA LcIMS1 was isolated from cultured cells of Luffa cylindrica Roem. by heterologous hybridization with cDNA of Glycyrrhiza glabra p-amyrin synthase. Expression of LcIMS1 in yeast lacking endogenous oxidosqualene cyclase activity resulted in the accumulation of isomultiflorenol a triterpene. This is consistent with LcIMS1 encoding isomultiflorenol synthase an oxidosqualene cyclase involved in bryonolic acid biosynthesis in cultured Luffa cells. The deduced aminoacid sequence of LcIMS1 shows relatively low identity with other triterpene synthases suggesting that isomultiflorenol synthase should be classified into a new group of triterpene synthases. The levels of isomultiflorenol synthase and cycloartenol synthase mRNAs which were measured with gene-specific probes correlated with the accumulation of bryonolic acid and phytosterols over a growth cycle of the Luffa cell cultures. Isomultiflorenol synthase mRNA was low during the early stages of cell growth and accumulated to relatively high levels in the late stages. Induction of this mRNA preceded accumulation of bryonolic acid. In contrast cycloartenol synthase mRNA accumulated in the early stages of the culture cycle whereas phytosterols accumulated at the same relative rate throughout the whole growth cycle. These results suggest independent regulation of .