Professor Mark Field, University of Dundee
Evolution of the nucleus: Eukaryogenesis and contributions towards parasite pathogenesis.
*Please note this seminar will be taking place Wednesday 03 Feb
The Nuclear envelope (NE) is the defining structure of the eukaryotic cell. Prominent structures of the NE are the nuclear pore complexes (NPC) and the filamentous lamina underlying the nuclear membranes. Until recently, these structures were only characterised in model organisms that belong to a relatively narrow eukaryotic group. Here we provide more insight into the evolution of the NE from pan-eukaryotic homology searches and phylogenetic analyses of the individual NE components and recent experimental data on the composition of the NE from the diverged eukaryotic parasiteTrypanosoma brucei.We found that an NPC very similar to that in humans was already present in the last eukaryotic common ancestor (LECA). Although lamins were assumed a derived feature of animal nucleus, we found lamin homologs with shared domain architecture and sequence motifs in diverse protists. The additional NE components facilitating connections between the nucleoskeleton and the NPC, cytoskeleton and chromatin were likely also integrated into the LECA lamina. Our data further suggest that different nucleoskeletal structures that support the nuclear membranes, organise chromatin and connect nucleus to the cytoskeleton operate at the nuclear periphery of trypanosomes. These findings contribute to the understanding of the origin and evolution of the eukaryotic cell.