Biochemists have identified two long-sought enzymes that help a tropical plant to produce a potent cancer treatment.
The Madagascar periwinkle (Catharanthus roseus) makes the anti-cancer compound vinblastine, but only in small amounts. Researchers have been keen to engineer microbes that can make larger amounts of the drug. But 2 of the 31 steps in the vinblastine synthetic pathway remained unknown.
Sarah O’Connor at the John Innes Centre in Norwich, UK, Vincent Courdavault at the University of Tours in France, and their colleagues suspected that the missing enzymes transform a single compound into structures that form the frameworks for two components that later combine to make vinblastine. The team searched a database of periwinkle RNA and identified two enzymes with the desired functions. Both are made at the same time as the plant is producing other enzymes involved in vinblastine synthesis.
When the authors shut off either of the genes that code for these enzymes, the plant failed to produce the corresponding framework.