Publications

• A stereoselective hydroxylation step of alkaloid biosynthesis by a unique cytochrome P450 in Catharanthus roseus.

  Giddings L.-A., Liscombe D.K., Hamilton J.P., Childs K.L., Dellapenna D., Buell C.R., O'Connor S.E.

  Plant cytochrome P450s are involved in the production of over a hundred thousand metabolites such as alkaloids, terpenoids, and phenylpropanoids. Although cytochrome P450 genes constitute one of the largest superfamilies in plants, many of the catalytic functions of the enzymes they encode remain ... >> More

  Plant cytochrome P450s are involved in the production of over a hundred thousand metabolites such as alkaloids, terpenoids, and phenylpropanoids. Although cytochrome P450 genes constitute one of the largest superfamilies in plants, many of the catalytic functions of the enzymes they encode remain unknown. Here, we report the identification and functional characterization of a cytochrome P450 gene in a new subfamily of CYP71, CYP71BJ1, involved in alkaloid biosynthesis. Co-expression analysis of putative cytochrome P450 genes in the Catharanthus roseus transcriptome identified candidate genes with expression profiles similar to known terpene indole alkaloid biosynthetic genes. Screening of these candidate genes by functional expression in Saccharomyces cerevisiae yielded a unique P450-dependent enzyme that stereoselectively hydroxylates the alkaloids tabersonine and lochnericine at the 19-position of the aspidosperma-type alkaloid scaffold. Tabersonine, which can be converted to either vindoline or 19-O-acetylhörhammericine, represents a branch point in alkaloid biosynthesis. The discovery of CYP71BJ1, which forms part of the pathway leading to 19-O-acetylhörhammericine, will help illuminate how this branch point is controlled in C. roseus. << Less

  J. Biol. Chem. 286:16751-16757(2011) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.

• The assembly of (+)-vincadifformine- and (-)-tabersonine-derived monoterpenoid indole alkaloids in Catharanthus roseus involves separate branch pathways.

  Williams D., Qu Y., Simionescu R., De Luca V.

  The biological activity of monoterpenoid indole alkaloids (MIAs) has led to their use in cancer treatment and other medical applications. Their biosynthesis has involved the formation of reactive intermediates by responsible enzymes to elaborate several different chemical scaffolds. Modification o ... >> More

  The biological activity of monoterpenoid indole alkaloids (MIAs) has led to their use in cancer treatment and other medical applications. Their biosynthesis has involved the formation of reactive intermediates by responsible enzymes to elaborate several different chemical scaffolds. Modification of scaffolds through different substitution reactions has produced chemically diverse MIAs and related biological activities. The present study characterizes the three-step pathway involved in the formation of (+)-echitovenine, the major O-acetylated MIA of Catharanthus roseus roots, and differentiates it from a parallel pathway involved in the formation of hörhammericine. Separate hydrolases convert a common reactive MIA intermediate to aspidosperma skeletons of opposite specific rotations, that is (+)-vincadifformine and (-)-tabersonine, respectively. The formation of (+) minovincinine from (+) vincadifformine 19-hydroxylase (V19H) is catalyzed by a root-specific cytochrome P450 with high amino acid sequence similarity to the leaf-specific tabersonine-3-hydroxylase involved in vindoline biosynthesis. Similarly, O-acetylation of (+)-minovincinine to form (+) echitovenine involves minovincinine-O-acetytransferase. The substrate specificity of V19H and MAT for their respective (+)-enantiomers defines the separate enantiomer-specific pathway involved in (+)-echitovenine biosynthesis and differentiates it from a parallel (-)-enantiomer-specific pathway involved in the formation of hörhammericine from (-)-tabersonine. << Less

  Plant J. 99:626-636(2019) [PubMed] [EuropePMC]

  This publication is cited by 9 other entries.