Fig. 6: Mechanistic studies of optimal AMPs.
a, SEM images of CRAB QLH-2022-637 and MRSA QLH-2022-718 treated with m_AMP76. The control groups were untreated corresponding strains. b, Schematic showing the behaviour of PI and DiSC3-(5), the fluorescent probes used to indicate disruption and depolarization of the cytoplasmic membrane caused by the AMPs, respectively. c,d, Changes in cell membrane permeability when CRAB QLH-2022-637 (c) or MRSA QLH-2022-718 (d) were co-cultured with AMPs (at concentrations of 1- and 5-fold MIC, respectively). Experiments were performed in 3 independent replicates. PC group, positive control (high-temperature-treated bacteria, with PI). NC group, negative control (untreated bacteria, with PI). The vertical coordinate is the ratio of FSC-A− and PI-A+ after PI treatment. All AMP-treated groups and the PC group were compared to the NC group. Error bars are the s.d. of triplicate experiments. Statistical analysis was conducted using two-sided t-test. Exact P values are provided in Source Data Fig. 6. e,f, DiSC3-(5) assays show the effect of AMPs on the membrane depolarization of CRAB QLH-2022-637 (e) or MRSA QLH-2022-718 (f). Relative fluorescence was calculated using as baseline the untreated control (buffer + bacteria + fluorescent dye). The graphs show the mean ± s.d. of 3 independent experiments. g, Heat map of differential gene expression related to cell membrane or cell wall synthesis. The colours of the heat map squares represent the magnitude of the ratio, which is the FPKM value of a gene for each sample in the Arkwillin-treated group divided by the mean value of the control group for the same gene. The schematic in b was created with BioRender.com.
