Eukaryogenesis is a major evolutionary transition in the history of life, that led to the emergence of extensive intracellular compartmentalization within cells, and thus eukaryotes. Much of the core architecture of the eukaryotic cell was established well over one billion years ago. Significantly, many cellular systems possess lineage-specific features, and architectural and compositional variation of complexes and pathways are likely keyed to specific functional adaptations. To reconstruct eukaryogenesis and the pathways that lead to and from the prokaryote/eukaryote transition, we must look for the imprints that this process left at the structural and molecular levels in the architecture of protein assemblies in modern-day conserved eukaryotic molecular machines, such as the NPC, a ubiquitous eukaryotic mega-machine responsible for mediating and regulating flux between the nucleus and the cytoplasm. However, most of our knowledge of the NPC structure are function are derived from decades of work in yeast and vertebrates, both members of the Opisthokonta, one of five or six major supergroups of the eukaryotic lineage.
Thus, to expand our understand and trace some of the evolutionary history of the NPC, we turned to trypanosomes, a diverse family of parasitic protozoans that are obligatory parasites of invertebrates, vertebrates, and plants, and thus cause major public health and economic problems in the developing world. cause major public health and economic problems in the developing world and more recently in the United States (Chagas disease). Trypanosomes are members of the Excavata supergroup, early diverging eukaryotes that exhibit biological traits that were once considered unique to trypanosomes, but that have now proven to be shared amongst other eukaryotic lineages. Indeed, several key features of molecular biology were first identified in trypanosomes. Examples include antigenic variation, GPI-anchored proteins, RNA editing, polycistronic transcription and trans-splicing.