Actinomycin, discovered in Streptomyces antibioticus in 1940, is the first natural antibiotic that has anti-cancer activity. Unfortunately, actinomycin does not specifically kill cancer cells, so it too toxic for general use. This molecule works by intercalating into the DNA double helix and interfering with topoisomerase activity. Topoisomerases, which untangle and reduce tension of DNA strands in cells, break down DNA before making topological changes and reassembling the DNA. Actinomycin and other intercalating drugs prevent topoisomerases from reassembling the DNA after it has been broken down. Actinomycin (shown as the green/blue structure in the figure below) is composed of two parts:
- a flat ring (shown in green) that resembles DNA bases, and
- two cyclic peptides composed of unusual amino acids (shown in blue)
Actinomycin intercalates between the bases in a DNA helix
To represent actinomycin artistically, we can use a half unraveled bracelet to represent DNA with a knot or bead to represent actinomycin and the effect it has on DNA. We could also used a half tangled slinky to represent DNA with something jammed in between the layers to represent actinomycin.
