Funtionelle Charakterisierung von mTERF-homologen mitochondriellen Proteinen in pflanzlichen Systemen am Beispiel des kernkodierten Faktors MOC1 aus C. reinhardtii

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Mitochondria play a fundamentally important role in cellular metabolism, but as yet there is still very little knowledge about how the expression of mitochondrial genes is regulated. Research efforts over the past few years, mainly concentrated on animal systems, have led to the identification of the evolutionary conserved mTERF (mitochondrial transcription termination factor) protein family. mTERF factors exist in higher and lower eukaryotes and are involved in different steps of mitochondrial gene expression, ranging from replication of the mitochondrial genome to translation of mitochondrial mRNAs. Sequenced genomes of photosynthetic organisms also contain mTERF genes, but apart from one Chlamydomonas reinhardtii mTERF protein no data exist for other plant mTERFs. The C. reinhardtii protein, designated MOC1, was identified by a random mutagenesis approach and shown to be essential for normal photosynthetic light-acclimation. Examination of the MOC1 null mutant, Stm6, revealed that mitochondrial gene expression, and in particular the expression of mitochondria-encoded components of the respiratory electron transport chain, was aberrant in the light. In plant cells, mitochondria are known to participate in complex interorganellar interactions with chloroplasts and the nucleus, but as yet the molecular basis behind changes in mitochondrial gene expression, especially in the light, are unclear. The aim of this research project is to fully characterize the role of mTERF proteins in Chlamydomonas reinhardtii and will involve the use of the mutant strain stm6. Within the project the molecular mechanism by which mTERF proteins intervene in gene expression will be addressed. As a result I expect to gain important genral insights into the function of mTERF proteins in plant systems.