Scientists have been engineering new genes into plants for a number of years in an effort to expand on naturally occurring medicinal compounds. Now chemists at MIT have gone one step further, using an approach known as metabolic engineering to alter the series of reactions plants use to build new molecules, thereby enabling them to produce unnatural variants of their usual products.
Instead of adding a gene that codes for a novel protein, metabolic engineering deals with the series of reactions within cells to increase the production of a certain substance. By adding new genes for new enzymes it is possible to reshape the way the host organism builds new molecules. Most metabolic engineers use bacteria as their host organism, partly because their genes are easier to manipulate, but Associate Professor Sarah O’Connor was drawn to engineering plants.
O’Connor led a team that added bacterial genes to the periwinkle plant, enabling it to attach halogens such as chlorine or bromine to a class of compounds called alkaloids that the plant normally produces. Many alkaloids have pharmaceutical properties while halogens are often added to antibiotics and other drugs because they can make medicines more effective or last longer in the body.