DFG-Project MagPass

Assembly of a prokaryotic organelle

The biogenesis of membrane-bounded cell organelles requires a multitude of cellular actions, among them principal processes like re-modelling of membranes and spatio-temporally coordinated assembly of proteins. While in eukaryotes these processes are comparably well understood, prokaryotic organelle-formation has so far not been characterized in detail.

MagPass focuses on the protein assembly during biogenesis of magnetosomes, unique magnetic organelles of magnetotactic bacteria. Preliminary results show that MamF-like proteins play a central role in defining the protein composition of magnetosomes, and our objective is now to characterize the function of MamF-like proteins in magnetosome assembly in more detail. For this, we plan to use proteomic and immunochemical approaches to first identify those proteins that get ill-targeted in a mutant devoid of all mamF-like genes. Then, we will employ bacterial two-hybrid-assays and PAGE-based methods to investigate whether these putative substrates of a postulated protein "sorting-complex" comprised of MamF-like proteins interact directly with constitutents of this sorting-complex. Moreover, we aim to identify targeting-determinants for the magnetosome membrane (MM) from sequence comparison of substrate- and MamF-like proteins. These determinants will be useful for the establishment of a magnetosome-targeting-assay based on fluorescence microscopy. By means of this assay it will be possible to analyze the mechanism and the temporal sequence of MamF-mediated MM-protein arrangement, which can then be verified by microscopic, physiological and biochemical methods.

In the first place, this project is expected to yield new insights into the process of prokaryotic organelle formation. Moreover, comparison with eukaryotic systems will allow also a deeper understanding of the evolution of organell-specific protein-translocases.

Principal Investigator: PD Dr. René Uebe