Self is the bacterium
Bacteria have often been used to produce proteins. Now scientists have altered the metabolic pathways of a bacterium to create a drug against cancer. According to the researchers, this method is much simpler - and potentially cheaper - than traditional chemical methods of producing the drug. Doxorubicin, a compound produced by Streptomyces peucetius, is used medicinally to treat breast, liver, lymph node, and other cancers. To produce a more potent variant of this medicine, the chemists modified doxurubicin by rearranging an attached sugar group. A promising drug in this second generation is epirubicin. Epirubicin has fewer side effects than the original compound and is currently in use. However, the production of epirubicin “in the test tube” is time-consuming and difficult. Now, University of Wisconsin (Madison) researcher Richard Hutchinson and his collaborators have devised an ingenious way to get bacteria to do this heavy lifting (Nature Biotechnology, January 1998 issue).
Hutchinson's group first switched off a gene in S. peucetius bacteria that codes for an enzyme required in the biosynthesis of doxorubicin. This enzyme normally reduces certain sugar molecules before they are attached to the main components of doxorubicin. The gene was replaced with a gene from another bacterium. The "replacement" enzyme that was now formed modified the sugar group of doxorubicin like the original enzyme, but caused a different orientation. By binding this modified sugar to the main constituent, epirubicin is formed.
