Fig 1.

Culture supernatant cleavage activity of gingipain knockout strains. Culture supernatants of P. gingivalis W50 knockout strains ΔRgp (KDP133), ΔKgp (K1A), and ΔKgp/ΔRgpA/ΔRgpB (KDP136) were incubated with each FRET substrate (A to H) at 37°C. As a positive control, wild-type strain W50 (WT) was used. Cleavage of the substrates was defined in RF/min. The enzyme activity of knockout strains was compared to P. gingivalis W50 activity using the unpaired, two-tailed Student t test. Results are expressed as mean ± standard error of the mean (n = 3). ***, P < 0.0001; **, P < 0.01.