PMC

Structure of brilacidin (PMX30063).

Upregulation of Staphylococcus aureus two-component systems. Shown are fold changes in expression levels of genes belonging to the GraSR (A), NsaSR (B), VraSR (C), and WalKR (D) two-component systems. The y axis is log₂ transformed for clarity.

Global pairwise correlations of transcript levels. Pearson correlation coefficients were calculated for all possible 61-by-61 combinations of conditions evaluated by RNA-seq. Correlations range from −0.79 to 0.85, with significant positive correlation within drug treatments.

Induction of the Dap operon, the Dlt operon, and proteases/chaperones. Heat maps of gene induction (log₂ transformed) of the Dlt operon (A), the Dap operon (B), and select proteases and chaperones (C) are shown. Brilacidin and LL16 caused a strong induction of the Dap operon as well as a modest upregulation of the Dlt operon, while daptomycin and higher concentrations of brilacidin treatment caused upregulation of proteases and chaperones.

Membrane depolarization of Staphylococcus aureus. Newman cultures suspended in buffer supplemented with Ca²⁺ were treated with 1, 2, and 4 μg/ml of brilacidin and daptomycin for 30 min and stained with DiOC₂(3) for 15 min. Red/green fluorescence emission ratios were determined for 30,000 cells by flow cytometry, with a decrease in the red/green ratio indicating depolarization of the membrane. The protonophore CCCP was used as a positive control for membrane depolarization.