Evolution of the vesicle fusion machinery

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Transport of cargo between organelles in eukaryotic cells is mediated by vesicles that bud from a donor compartment and fuse specifically with an acceptor membrane. Currently, it is becoming clear that the molecular machineries involved in the principal aspects of vesicular trafficking are highly conserved, not only between different species but also between different vesicle trafficking steps within the cell. In all steps, the central machinery involved in the fusion process is composed of members of the SNARE protein family. It is thought that this machinery is tightly controlled by members of the Sec1/Munc18 (SM) family of proteins. For other important factors, however, it is often unclear whether they have a role in all trafficking steps or whether they represent special adaptations of certain trafficking steps or certain eukaryotic lineages. We therefore want to establish a detailed description of the evolutionary history of the protein machinery involved in the vesicle fusion process. The evolutionary history of the different protein families involved in this process will be mapped onto the species tree. This will allow us to discover how the mechanism has adapted in different eukaryotic lineages and in different vesicle trafficking steps within the cell. Ultimately, we want to identify the key elements of the prototypic vesicle fusion mechanism and to pinpoint its functionally important sites. In addition, this will enable us to discover co-evolutionary patterns between interacting proteins. Moreover, we hope to gain insights into phylogenetic relationships between the major eukaryotic lineages and into the evolution of the eukaryotic endomembrane system.