Publications

• Biosynthesis of eupatolide-A metabolic route for sesquiterpene lactone formation involving the P450 enzyme CYP71DD6.

  Frey M., Schmauder K., Pateraki I., Spring O.

  Sesquiterpene lactones are a class of natural compounds well-known for their bioactivity and are characteristic for the Asteraceae family. Most sesquiterpene lactones are considered derivatives of germacrene A acid (GAA). GAA can be stereospecifically hydroxylated by the cytochrome P450 enzymes (C ... >> More

  Sesquiterpene lactones are a class of natural compounds well-known for their bioactivity and are characteristic for the Asteraceae family. Most sesquiterpene lactones are considered derivatives of germacrene A acid (GAA). GAA can be stereospecifically hydroxylated by the cytochrome P450 enzymes (CYP) Lactuca sativa costunolide synthase CYP71BL2 (LsCOS) and Helianthus annuus GAA 8β-hydroxylase CYP71BL1 (HaG8H) at C6 (in α-orientation) or C8 (in β-orientation), respectively. Spontaneous subsequent lactonization of the resulting 6α-hydroxy-GAA leads to costunolide, whereas 8β-hydroxy-GAA has not yet been reported to cyclize to a sesquiterpene lactone. Sunflower and related species of the Heliantheae tribe contain sesquiterpene lactones mainly derived from inunolide (7,8-cis lactone) and eupatolide (8β-hydroxy-costunolide) precursors. However, the mechanism of 7,8-cis lactonization in general, and the 6,7-trans lactone formation in the sunflower tribe, remain elusive. Here, we show that, in plant cells, heterologous expression of CYP71BL1 leads to the formation of inunolide. Using a phylogenetic analysis of enzymes from the CYP71 family involved in sesquiterpenoid metabolism, we identified the CYP71DD6 gene, which was able to catalyze the 6,7-trans lactonization in sunflowers, using as a substrate 8β-hydroxy-GAA. Consequently, CYP71DD6 resulted in the synthesis of eupatolide, thus called HaES ( Helianthus annuus eupatolide synthase). Thus, our study shows the entry point for the biosynthesis of two distinct types of sesquiterpene lactones in sunflowers: the 6,7-trans lactones derived from eupatolide and the 7,8-cis lactones derived from inunolide. The implications for tissue-specific localization, based on expression studies, are discussed. << Less

  ACS Chem. Biol. 13:1536-1543(2018) [PubMed] [EuropePMC]

  This publication is cited by 3 other entries.

• Discovery of a non-stereoselective cytochrome P450 catalyzing either 8alpha- or 8beta-hydroxylation of germacrene A acid from the Chinese medicinal plant, Inula hupehensis.

  Gou J., Hao F., Huang C., Kwon M., Chen F., Li C., Liu C., Ro D.K., Tang H., Zhang Y.

  Sesquiterpene lactones (STLs) are C15 terpenoid natural products with α-methylene γ-lactone moiety. A large proportion of STLs in Asteraceae species is derived from the central precursor germacrene A acid (GAA). Formation of the lactone rings depends on the regio-(C6 or C8) and stereoselective (α- ... >> More

  Sesquiterpene lactones (STLs) are C15 terpenoid natural products with α-methylene γ-lactone moiety. A large proportion of STLs in Asteraceae species is derived from the central precursor germacrene A acid (GAA). Formation of the lactone rings depends on the regio-(C6 or C8) and stereoselective (α- or β-)hydroxylations of GAA, producing STLs with four distinct stereo-configurations (12,6α-, 12,6β-, 12,8α-, and 12,8β-olide derivatives of GAA) in nature. Curiously, two configurations of STLs (C12,8α and C12,8β) are simultaneously present in the Chinese medicinal plant, Inula hupehensis. However, how these related yet distinct STL stereo-isomers are co-synthesized in I. hupehensis remains unknown. Here, we describe the functional identification of the I. hupehensis cytochrome P450 (CYP71BL6) that can catalyze the hydroxylation of GAA in either 8α- or 8β-configuration, resulting in the synthesis of both 8α- and 8β-hydroxyl GAAs. Of these two products, only 8α-hydroxyl GAA spontaneously lactonizes to the C12,8α-STL while the 8β-hydroxyl GAA remains stable without lactonization. Chemical structures of the C12,8α-STL, named inunolide, and 8β-hydroxyl GAA were fully elucidated by nuclear magnetic resonance analysis and mass spectrometry. The CYP71BL6 displays 63-66% amino acid identity to the previously reported CYP71BL1/2 catalyzing GAA 6α- or 8β-hydroxylation, indicating CYP71BL6 shares the same evolutionary lineage with other stereoselective cytochrome P450s, but catalyzes hydroxylation in a non-stereoselective manner. We observed that the CYP71BL6 transcript abundance correlates closely to the accumulation of C12,8-STLs in I. hupehensis. The identification of CYP71BL6 provides an insight into the biosynthesis of STLs in Asteraceae. << Less

  Plant J. 93:92-106(2018) [PubMed] [EuropePMC]

  This publication is cited by 3 other entries.