Charakterisierung der Dolichol‑Phosphat‑Mannosyltransferase 1, ein Enzym der Biosynthese von Glykosylphosphatidylinositolen im Einzeller Babesia microti

The protozoan parasites Babesia divergens and Babesia microti are the causative agents of human babesiosis. These eukaryotic parasites are transmitted by Ixodes ticks and cause infection and disease in a variety of mammals, also in humans. In addition to acute flu-like symptoms also a latent course of disease with up to several months of a- or oligo symptomatic parasitaemia has been described. Diagnosis is made by demonstrating the intraerythrocytic parasites in blood smears or thick drop, which at low parasitaemia is challenging in discriminating it from malaria parasites. The enzyme dolichol phosphate mannosyl transferase 1 (DPM1) is an ubiquitous and evolutionarily highly conserved enzyme and forms an essential substrate (dolichol phosphate mannose), which is indispensable for the biosynthesis of glycosylphosphatidylinositols (GPIs) in the endoplasmic reticulum (ER). In this study, the protein DPM1 of Babesia microti (B. microti), for which little is known so far, was characterized in systematic steps with the aid of relevant bioinformatic databases and molecular biological techniques in terms of its evolutionary conservation and its genetic characteristics. It could be demonstrated by bioinformatic analysis of DPM1 from Babesia microti based on a phylogenetic tree compared to a variety of other organisms, that this protein concerning hydrophobicity, the presence of other auxiliary proteins of the DPM-family, the presence of a GPI-anchor as well as a signal peptide cleavage site differs from DPM1 of the compared organisms. There has been seen relevant biochemical differences particularly from DPM1 of the yeast Saccharomyces cerevisiae (S. cerevisiae). Nonetheless, in this study, using molecular biological techniques, the functional complementation of DPM1 of the DPM1‑deficient‑S. cerevisiae‑mutant, for which the DPM1 protein is essential, with parasitic DPM1 could be demonstrated. This shows the species independent evolutionary conservation of this protein and its functional interchangeability.