Role of cell surface mobility on bacteriophage infection: Translocation of salmonella phages to membrane adhesions

Abstract

Phage ϵ 15 adsorbed at a low temperature (or by short-time incubation) to the outer surface of Salmonella anatum gathers on further incubation at a high temperature to a certain region where the inner and outer membranes may join. This was demonstrated by separating the inner and outer membranes of the cells in sucrose gradient after addition of 35S-labeled ϵ 15 to the cells. Radioactivity adsorbed at 4° was first recovered mainly with the dense outer membrane but disappeared by further incubation at 35° within 5 min. Instead, the radioactivity was recovered with the membrane fraction which had intermediate density. Such phage translocation was not observed when phage ϵ 15 was added to a pep mutant of S. anatum to which the phage can adsorb but fail to infect. A host range mutant phage which can infect the pep mutant migrated to the intermediate dense region.