Differential effects of analogs of cycloheximide on protein and RNA synthesis in Achlya

Analogs of the glutarimide antibiotic cycloheximide were tested for their effect on growth and incorporation of proline and uridine into acid-insoluble material in Achlya bisexualis. Each of the compounds tested had reduced antibiotic activity as compared to cycloheximide. The effects of the antibiotics on protein and RNA synthesis were varied. While cycloheximide inhibited both protein and RNA synthesis immediately, two of the analogs inhibited proline incorporation without effect on uridine incorporation, while three, each representing a modification of the hydroxyl of cycloheximide, stimulated uridine incorporation and either had no effect on or inhibited protein synthesis. These results indicate that the control of RNA synthesis by protein synthesis in Achlya can be released by glutarimide antibiotics.