The Action of Colicins on Eukaryotic Cells

AbstractColicins, known as specific antibacterial proteins, exert comparable effects in animal cells, though not in yeast protoplasts.Protists are highly colicin-sensitive. In Euglena gracilis, chlorophyll synthesis and growth are inhibited by colicin E2. Colicin El causes a severe cytotoxic and cytocidal effect on the aerobic flagellate Crithidia sp., while colicin K exerts a similar effect on the anaerobic Tritrichomonas foetus. Thus they probably use different biochemical pathways of action in protists.Colicin E3 completely and specifically inhibits the concana-valin A-promoted mitogenic activation of mouse lymphocytes (which is not due to the competition for receptors) and impairs their recirculation into lymph nodes. Colicin E3 also interferes with DNA synthesis in mouse lymphatic leukemia cells and with their proliferation. In “professional phagocytes” of guinea-pig peritoneal exudates, low doses of colicin E3 stimulate the oxidoreductive metabolism.A variety of mammalian normal tissue cells in vitr...