Bacteria-like information processing in ancestral mitochondria

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HOW MITOCHONDRIA CAME ABOUT Mitochondria are an organ-like structure (organelle) within the cells of all eukaryotes (animals including humans, fungi, plants, and the large and diverse assemblage of protozoans/protists). While usually referred to as the cell's powerhouse, mitochondria play also an import metabolic role: they supply the entire cell with various building blocks (carbohydrates, amino acids, nucleotides, fatty acids, and iron-sulfur compounds). We now know that mitochondria possess their own genome and particular machineries for organelle division, DNA replication, transcription of genes into messenger RNAs, and translation of messenger RNAs into proteins (the material from which cellular membranes and enzymes are made). This semi-autonomy of mitochondria is a vestige of their ancestry: they originate from endosymbiotic bacteria that took up residence in the eukaryotic cell about a billion years ago. In the initial transition phase from a symbiotic bacterium to an organelle, the proto-mitochondrial genome must have encoded more than a thousand genes specifying mitochondrial proteins, and adhered to bacterial conventions with respect to genome organization, RNA transcription and protein translation. However, in present-day mitochondria from animals, fungi and plants, gene organization and gene expression bear little traces of their bacterial past. Our research program aims at elucidating the steps that were involved in the 'domestication' of the endosymbiotic bacterial ancestor, and tracing the processes by which the predecessor of mitochondria was transformed into a eukaryotic organelle. These questions can now be tackled effectively through our discovery --in unicellular, flagellated protozoans called jakobids-- of mitochondrial DNAs resembling bacterial genomes in miniature. In the first five years of our program, we propose to investigate to which degree mitochondrial information processing, from gene via RNA to protein, resembles that of bacteria or rather 'modern' mitochondria as we known them from animals, fungi, and plants. Our approach will combine classical biochemistry, new generation genomics methodologies and bioinformatics, and provide ample multi-disciplinary training opportunities for students at all levels.