FIG 6.

Modification of the tail tip after binding of phage T5 and tails to FhuA. (A) T5st0 particles incubated with purified FhuA and treated with Benzonase before EM (see Materials and Methods). A control image of T5 particles treated in the absence of FhuA is shown in subpanel a. The loss of the central tail fiber was visible in all phages with an empty capsid (c and d) and also in some phages with filled heads (b). The position of pb2 was visualized with gold-conjugated anti-pb2 IgG only in phage particles whose central fiber was affected (b and d). (B) EM images of partially purified tail preparations (addition of LDAO was omitted): free tails (a) and tails bound to membrane vesicles (b, c, and d). Bound tails include filled (b) and intermediate (c) tails and empty ones from pb2 (d), as indicated with black arrows, an open white arrow, and a solid white arrow, respectively. Upper bar, 100 nm; bottom bar, 50 nm.