  5.4.99.31 | more |
2,3-oxidosqualene production is implemented and subsequently combined with different cyclization reactions catalyzed by the representative oxidosqualene cyclases CAS1 (cycloartenol synthase), LUP1 (lupeol synthase), THAS1 (thalianol synthase) and MRN1 (marneral synthase), derived from model plant Arabidopsis thaliana, in the two alternative hosts for biosynthesis of cyclic plant triterpenes, the metabolically versatile photosynthetic alpha-proteobacterium Rhodobacter capsulatus strain SB1003 and cyanobacterium Synechocystis sp. PCC 6803, triterpene pathway design, overview. While successful accumulation of 2,3-oxidosqualene can be detected by LC-MS analysis in both hosts, cyclase expression results in differential production profiles. CAS1 catalyzes conversion to only cycloartenol, but expression of LUP1 yields lupeol and a triterpenoid matching an oxidation product of lupeol, in both hosts. In contrast, THAS1 expression does not lead to cyclic product formation in either host, whereas MRN1-dependent production of marnerol and hydroxymarnerol is observed in Synechocystis but not in Rhodobacter capsulatus. 2,3-Oxidosqualene cyclization in heterologous phototrophic bacteria is basically feasible but efficient conversion depends on both the respective cyclase enzyme and individual host properties |
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