The mode of action of ASK-753 on Bacillus subtilis.

The mode of action of ASK-753 on Bacillus subtilis was examined. Unlike proper sideromycin antibiotics ferrioxamine B failed to antagonize the antimicrobial effects of ASK-753. The antibiotic could inhibit the biosynthesis of nucleic acids; effect on the RNA was more pronounced. ASK-753 affected the stability of prelabelled DNA of B, subtilis in growing or resting cultures; the effect on the latter was more pronounced. Lysis of B, subtilis protoplasts could be attained at 30 degrees C but not at 4 degrees C which excludes a possible detergent affect of the drug. The drug exerted a potent inhibiting influence on protein synthesis by arresting the activity of lysyl-tRNA synthetase and thus could prevent the incorporation of 14C-lysine.