Expression of deacetylvindoline-4-O-acetyltransferase in Catharanthus roseus hairy roots

Madagascar periwinkle [Catharanthus roseus (L.) G Don] is a pantropical plant of horticultural value that produces the powerful anticancer drugs vinblastine and vincristine that are derived from the dimerization of the monoterpenoid indole alkaloids (MIAs), vindoline and catharanthine. The present study describes the genetic engineering and expression of the terminal step of vindoline biosynthesis, deacetylvindoline-4-O-acetyltransferase (DAT) in Catharanthus roseus hairy root cultures. Biochemical analyses showed that several hairy root lines expressed high levels of DAT enzyme activity compared to control hairy root cultures expressing beta-gulucuronidase activity (GUS) activity. Metabolite analysis using high performance liquid chromotagraphy established that hairy root extracts had an altered alkaloid profile with respect to horhammericine accumulation in DAT expressing lines in comparison to control lines. Further analyses of one hairy root culture expressing high DAT activity suggested that DAT expression and accumulation of horhammericine (9) were related. It is concluded that expression of DAT in hairy roots altered their MIA profile and suggests that further expression of vindoline pathway genes could lead to significant changes in alkaloid profiles. Evidence is provided that horhammericine (9) accumulates via a DAT interaction with the root specific minovincinine-19-O-acetyltransferase (MAT) that inhibits the MAT mediated conversion of hammericine (9) into 19-O-acetyl-horhammericine (12). (c) 2007 Elsevier Ltd. All rights reserved.