How Bacteriophage χ Attacks Motile Bacteria

Abstract

Bacteriophage χ attaches to the filament of a bacterial flagellum by means of a tail fiber, but the ultimate receptor site for the phage is located at the base of the bacterial flagellum. Here, the phage injects its deoxyribonucleic acid into the bacterium, leaving the empty phage attached at the base. It is suggested that χ slides along the filament of the flagellum to the base, owing to the movement of the flagellum. The role of motility would thus be to provide for rapid adsorption of the phage by guiding the phage to the adsorption sites at the bases of the flagella. Bacteria whose motility has been strongly inhibited by cold or anaerobic conditions still adsorb χ at the filaments and bases of flagella if a high multiplicity is used. This indicates that direct collisions with the bases may also be possible. Bacteria must be flagellated in order for χ to attach, but only a short flagellum, perhaps only the flagellar base, is necessary.