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. 2012 Apr 18;287(24):20270–20280. doi: 10.1074/jbc.M112.369561

FIGURE 3.

FIGURE 3.

Impact of empedopeptin on the peptidoglycan precursor pool and membrane potential of staphylococci. Intracellular accumulation of the soluble cell wall precursor UDP-MurNAc-pentapeptide in S. aureus ATCC 29213 is shown (A). Cells were treated with empedopeptin (solid line), vancomycin (dotted line), or both at 10-fold MIC or left untreated (dashed line). The intracellular nucleotide pool was analyzed after extraction. HPLC analysis and subsequent mass spectrometry (small inset panel) confirmed the identity of UDP-MurNAc-pp. Its monoisotopic mass (m/z) is 1149.35 Da. In addition to the singly charged ion, the mono- and disodium salts were detected. The influence of empedopeptin on the membrane potential of S. aureus SG511 (B) is shown. ΔΨ was calculated from the distribution of the lipophilic cation TPP+ inside and outside the cells. The arrow indicates the time of antibiotic or carbonyl cyanide m-chlorophenylhydrazone addition, respectively. Triangles, empedopeptin (10× MIC); squares, carbonyl cyanide m-chlorophenylhydrazone (500 μm); diamonds, control.