SDS-PAGE profile of proteins present in NgoΦfil phage particles propagated in <i>N</i>. <i>gonorrhoeae</i> cells.

Phage particles were purified as described in the Materials and Methods, and proteins were separated on a 5–15% gradient gel. Panel A; Lane M; molecular weight standard. Lane 1; phage proteins. Numbers on the right (1 and 3; 12.5 kDa and 25 kDa) indicate phage-encoded structural proteins found in the phage particle preparation, while numbers 2, 4, 5 and 6 indicate host outer membrane proteins of molecular sizes 18 kDa, 30 kDa, 32 kDa and 35 kDa respectively. Several additional proteins are also visible. (For the original gel, see S1 Fig). Panel B; Transmission electron micrograph of NgoΦ6fil isolated from N. gonorrhoeae FA1090 cells. Culture supernatants were precipitated with PEG 8000 and NaCl, purified on Sephacell QMA columns, dialyzed against TE buffer, added to a gold grid, stained with uranyl acetate, and visualized on a Zeiss EM10CA electron microscope.