E-PROTEINS OF BACTERIOPHAGE-P22 .1. IDENTIFICATION AND EJECTION FROM WILD-TYPE AND DEFECTIVE PARTICLES

Of the 9 proteins found in the virion of phage P22, 4 are ejected into the cell [Salmonella typhimurium] after adsorption. The 4 ejected proteins, termed E proteins, are gp16, gp20, gp26 and gp7. This was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of radioactively labeled phage that were adsorbed to cells and then eluted off the surface with distilled water. Phage particles that lack pg7 (7- particles) or gp20 (20- particles) successfully eject all their E proteins. The 16- particles do not eject gp7. Analysis of phage ghosts showed that they lack gp16, gp20 and gp7, but they have gp26 in close to normal quantities. The roles for gp16 and gp26 in DNA and E protein ejection were suggested. All 4 E proteins are possible candidates for roles in helping the phage DNA cross the plasma membrane.