FIG. 4.

Mechanism studies of inhibitors MBX 1066 and MBX 1090. (A) Effect of compounds on growth of B. subtilis BD54. Assays were performed in the absence or presence of compounds at 5× their MICs. OD600, optical density at 600 nm. (B to E) Effect of compounds on macromolecular biosynthesis in B. subtilis BD54. Assays were performed using radiolabeled precursors and B. subtilis BD54 as described in Materials and Methods with compounds MBX 1066 and MBX 1090 and appropriate control antibiotics present at 5× their MICs as indicated. Macromolecular pathways and control antibiotics are as follows: DNA synthesis, ciprofloxacin control (B); RNA synthesis, rifampin control (C); protein synthesis, chloramphenicol control (D); cell wall synthesis, vancomycin control (E). (F) Effect of compounds on bacterial membrane permeability. Compounds were incubated with B. subtilis BD54 at various concentrations (0.25×, 1×, 5×, and 10× their MICs) in the presence of DiSC₃(5) dye. Control is DNP.