Fig. 1: comK is induced in response to oxidative stress.

A (i) qRT-PCR analysis of comK expression in S. aureus WT (wild type) and Kc, a strain that constitutively expresses comK (TSB medium 37 °C, agitation 200 rpm). (ii) DNA uptake efficiency of different S. aureus strains. Data represent the number of CFU per ml of erm⁺ lac⁺ colonies in relation to the total CFU per ml (CFU/ml). Significance was measured by two-tailed Student t test; ***p < 0.001. Data are shown as mean ± SD of three independent experiments (n = 3). B qRT-PCR analysis of comK expression during S. aureus infection of A549 human-lung epithelial cells (MOI 100); analysis at 2 and 4 h post-infection (h.p.i.). The inoculum was obtained from a TSB culture. As a control, fresh TSB medium was inoculated with a comparable number of S. aureus cells. Statistical analysis, two-tailed Student t test; ***p < 0.001. Data are shown as mean ± SD of three independent experiments (n = 3). C qRT-PCR analysis of comK expression in WT and Kc strains in the presence of H₂O₂ (5 mM) Data are shown as mean ± SD of three independent experiments (n = 3). D Immunodetection of ComK protein levels in WT and Kc strains in H₂O₂-treated and untreated cultures. Ponceau membrane staining is shown as a protein loading control (PLC). These results are representative of the results obtained in three independent experiments. E DNA uptake efficiency of WT and Kc strains in TSB cultures supplemented with H₂O₂ (5 mM). Data are shown as mean ± SD of three independent experiments (n = 3). F Survival (%) of different S. aureus strains in untreated TSB cultures or TSB cultures with H₂O₂ (5 mM). The survival rate was determined when cultures reached the mid-exponential phase. Statistical analysis, two-tailed Student t test; ***p < 0.001. Data are shown as mean ± SD of three independent experiments (n = 3). G S. aureus survival (%) in infected human monocyte-derived macrophages (MDM) (MOI 10) at 2 h.p.i. Differences were examined by one-sided ANOVA with Tukey’s test for multiple comparisons; ***p < 0.001. Data are shown as mean ± SD of three independent experiments (n = 3). H qRT-PCR analyses of comK expression in different S. aureus mutants in TSB cultures supplemented with H₂O₂ (5 mM). Differences were detected by one-sided ANOVA with Tukey’s test for multiple comparisons; ***p < 0.01, ***p < 0.001. Data are shown as mean ± SD of three independent experiments (n = 3). Source data are provided as a Source Data file.