Mode of action of morganocin 174.

Morganocin 174-induced lethality was characterized by one-hit kinetics. Although it induced simultaneous inhibition of deoxyribonucleic acid, ribonucleic acid, and protein syntheses, the most striking effect of morganocin was a rapid reduction of intracellular adenosine 5'-triphosphate to less than 10% of the initial values within 2 min of addition. Accumulation of thymidine, uridine, glutamine, and proline was also inhibited. A gradual efflux of K(+) was observed, but the lethal effects of morganocin 174 could not be prevented by maintaining a high K(+) or Mg(2+) concentration. The Mor174 plasmid codes for an immunity substance that protects cells against the effect of morganocin 174.