Antimicrobial and cytolytic polypeptides of amoeboid protozoa - effector molecules of primitive phagocytes

Amoebas are primitive, actively phagocytosing eukaryotic cells, many of whi ch use bacteria as a major nutrient source. One may suppose that amoebae po ssess an array of potent antimicrobial molecules acting in synergy to comba t bacterial growth inside their phagosomes. Lysosome-like granular vesicles of Entamoeba histolytica contain a family of 77-residue peptides with a co mpact alpha-helical, disulfide-bonded fold. These polypeptides. named amoeb apores, exhibit antibacterial and cytolytic. activity by forming pores in m embranes of various origin. It is of particular interest that amoebapores a re structurally and functionally most similar to polypeptides of mammalian cytotoxic lymphocytes. In addition, amoebic granules contain bacteriolytic proteins with lysozyme-like properties. Some amoebic polypeptides may repre sent archaic analogs of effector molecules from invertebrates and vertebrat es. (C) 1999 Elsevier Science Ltd. All rights reserved.