PURIFICATION AND MOLECULAR-CLONING OF A MAJOR ANTIBACTERIAL PROTEIN OF THE PROTOZOAN PARASITE ENTAMOEBA-HISTOLYTICA WITH LYSOZYME-LIKE PROPERTIES

A protein with potent antibacterial activity was purified to apparent homogeneity from pathogenic Entamoeba histolytica. It resembles lysozyme in that it is a basic protein which degrades cell walls of Micrococcus luteus, displays optimal activity at acidic pH, and shows a preference for Gram-positive bacteria. The protein has a molecular mass of approximate to 23 kDa upon SDS/PAGE and is localized inside the cytoplasmic granules of the amoebae. The primary structure was elucidated by protein analysis and molecular cloning of the corresponding cDNA. It yielded a protein of 198 residues with structural similarity to the distinct class of lysozymes found in Streptomyces species and the fungus Chalaropsis.