frederik.schulz
Free-living amoebae are abundant in various habitats worldwide and are among the most important predators of microorganisms having a major impact on the composition of microbial communities. During evolution some bacteria learned to evade phagocytosis by amoebae and to establish a stable and symbiotic relationship with these protozoa. Symbiosis is a key principle in nature; the eukaryotic cell emerged from an ancient symbiotic association and there is hardly any organism that is not involved in symbiotic interactions. Within the last years, there has thus been a major interest in understanding the relationship between bacterial symbionts and their eukaryotic hosts. Protozoa in particular have been suggested to play an important role for the evolution of intracellular bacteria including human pathogens. In my own previous research I isolated amoebae stably infected with bacteria that live inside the host nucleus. All known amoeba symbionts are located in the host cytoplasm, and no intranuclear symbiont has been described in amoebae so far. Intranuclear symbiosis is a rare phenomenon and requires a complex infection process. In this project I intend to perform a detailed characterization of this unique bacterial symbiont and its interaction with the amoeba host cell. Main aims will be (i) to study its biology and ecology, including the infection cycle, impact on host fitness, host range and global distribution, (ii) to sequence its genome, to perform comparative and phylogenetic genome analysis, and (iii) to carry out follow-up studies including transcriptome sequencing and experimental verification of predicted host interactions. These experiments will help to elucidate molecular mechanisms underlying the unusual intranuclear lifestyle of this amoeba symbiont. This study will contribute to our understanding of the evolution of intracellular bacteria, with possible implications also for the evolution of the eukaryotic cell.