OmpA-Like Proteins of Porphyromonas gingivalis Mediate Resistance to the Antimicrobial Peptide LL-37

Figure 1

Sensitivity of the wild-type and OmpALP-deficient strains of P. gingivalis to the bactericidal activities of hBD1, hBD2, hBD3, and LL-37. (a) Bacterial cells (10⁷) of the wild-type and Pgm6/Pgm7-deficient strains, suspended in sTSB containing the 2-fold serial concentrations of the indicated antimicrobial peptides (0.156–5 μM), were anaerobically cultured for 6 h. Bacterial survival was assessed by ATP production. Data are expressed as mean ± SD (n= 3). The statistical significance of differences was determined by the paired Student’s t-test. p < 0.05. (b) Approximately 10⁷ wild-type and Pgm6/Pgm7-deficient bacterial cells were anaerobically cultured for the indicated periods (6–48 h) in the presence of hBD1 or LL-37 (5 μM). Bacterial survival was assessed by ATP production. Data are expressed as mean ± SD (n= 3). The statistical significance of differences was determined by the paired Student’s t-test. p < 0.05. (c) Approximately 10⁷ wild-type or Pgm6/Pgm7-deficient bacterial cells were anaerobically cultured for 24 h in the presence of LL-37 (5 μM). The integrity of the outer membranes was assessed by fluorescence staining of bacterial cells with DMAO and EthD-III and then analyzed by fluorescence microscopy.

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