Translocation of Colicin from the Receptor to the Inner Cell Membrane" Function of the Peptidoglycan Layer

Sensitivity of spheroplasts (prepared in two ways) of a colicin-sensitive strain, of colicin- resistant and of colicin-tolerant mutants and of strains immune to colicins E1 and E2 was estimated and compared. Generally, the removal of the peptidoglycan layer brought about a slight nonspecific support for colicin translocation across the cell wall in sensitive, lolB tolerant and immune bacteria, tolB spheroplasts were colicin El-sensitive, but E2-insensitive. Spheroplasts were always fragile and lysed spontaneously, espe- cially those produced by lysozyme. Bacteria carrying tolA, tolQ and tolR mutations kept their colicin insen- sitivity as spheroplasts, just as the resistant ones. Bacteria rendered colicinogenic and hence colicin-immune turned to high colicin sensitivity in spheroplast form. The results indicate a change in plasma membrane associated with the spheroplast formation.