FIG 5.
Influence of nisin1–17-subtilin18–32 peptide on SpaI-/NisI-mediated immunity in a DiSC3(5) diffusion assay. (A) Primary structures of the lantibiotics tested in this study. (B) Control strain B168.KO (without immunity proteins) was incubated with DiSC3(5) fluorescent dye, and fluorescence was monitored (emission, 670 nm; excitation, 544 nm) after addition of the nisin-subtilin hybrid peptide. (C and D) The SpaI-expressing strain B186.SB2 (C) and the NisI-expressing strain B168.SB1 (D) were analyzed as described for panel B. Stars indicate the time of addition of 2.5 μM DiSC3(5) fluorescent dye. As a control, 1 μM valinomycin (red) was added to the cells. The increase of relative fluorescence units (RFU) was monitored after addition of a 30 nM or 100 nM concentration of the hybrid molecule nisin1–17-subtilin18–32 (green) at 150 s, indicated by a plus sign.