Properties of the ribosomes of antibiotic producers: effects thiostrepton and micrococcin on the organisms which produce them.

Ribosomes of Streptomyces azureus, which produces thiostrepton, are resistant to thiostrepton by virtue of being unable to bind the antibiotic. These ribosomes are also resistant to a number of other antibiotics (the thiostrepton group) which may share a common ribosomal binding site and a common mode of action with thiostrepton. Conversely, Bacillus pumilis and a strain of micrococcus, which produce the (probably identical) antibiotics micrococcin P and micrococcin, respectively, possess ribosomes which are susceptible to these antibiotics in vitro, although the organisms themselves are resistant.