Abstract
Myxovalargin A has two modes of action. At low concentrations (below 1 μg/ml) it inhibits bacterial protein synthesis specifically and instantaneously. In vitroexperiments suggest that it interferes with the binding of aminoacyl tRNA to the A site of the ribosome. At higher concentrations (above 5 μg/ml), or upon prolonged incubation, the antibiotic damages cell membranes. This leads to secondary effects, like decreased O2consumption or instant break down of RNA synthesis, and may be the reason for the irreversibility of the antibiotic action. The membrane effect is not restricted to prokaryotes and may explain the high toxicity of the compound for higher organisms.
