Figure 6.
Phage adsorption and TSP-mediated O-antigen cleavage. DNA ejection from phage HK620 (6.7 × 109 pfu) triggered by 16.7 μg/mL E. coli H TD2158 (O18A1) LPS in the presence of the fluorescent DNA-binding dye Yo-Pro at 45 °C (black circles). (A) Purified HK620TSP (3 nM) was added after 2 min (yellow triangles) or 5 min (blue circles). Controls: LPS digested with 0.3 nM HK620TSP for 30 min in the cuvette prior to adding phage (pink; A negative signal is due to correction for HK620 phage particle Yo-Pro staining over the full time course of the experiment) or LPS digested overnight with HK620TSP (green). (B) The mixture was kept in the cuvette at the restrictive temperature of 25 °C, where no ejection occurred (white) and only heated up to 45 °C after 2 (grey), 15 (red), 30 (green) or 60 min (yellow).