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Home > Departments > Cell Biology > Nathalie BONNEFOY : Biogenesis and Functionning of mitochondrial Oxphos Complexes in Yeasts and Mammals

Nathalie BONNEFOY : Group Presentation

Mitochondria are essential organelles found in all eukaryotes and their principal function is the production of ATP. Defects in mitochondrial function are seen in many metabolic and neuro-degenerative diseases and cancers. In the laboratory, we use yeasts to study mitochondrial biogenesis, model human diseases and screen for new drugs.

Mitochondria are very dynamic organelles, essential for the life of eukaryotic cells. Their main function is to produce ATP by OXidative PHOSphorylation via the OXPHOS complexes, which are a series of enzymes, located in the inner mitochondrial membrane. These complexes are of dual genetic origin; a few key subunits are encoded by the mitochondrial DNA while all the other subunits are encoded by the nuclear genome, imported into the mitochondria and assembled with the mitochondrially-encoded subunits and the co-factors. The proteins needed for the maintenance, regulation and expression of the mitochondrial genome, as well as the assembly factors required for the formation of the OXPHOS complexes are encoded in the nucleus. An optimal coupling between the synthesis of the subunits and their subsequent assembly into the OXPHOS complexes is facilitated by the fact that the mitochondrial ribosomes are bound to the inner-membrane.

Mitochondrial Biogenesis

Yeasts are particularly well adapted to study these processes, as they are facultative aerobes, able to survive without fully functioning respiratory chain, and two complementary yeast models are exploited in our group. We use the budding yeast Saccharomyces cerevisiae because it has a strong fermentative capacity and is experimentally very tractable and we use the fission yeast Schizosaccharomyces pombe, because its physiology and mitochondrial genome structure are very similar to humans; at present very few laboratories use S. pombe for mitochondrial studies.

The study of mitochondrial function and biogenesis combines fundamental, medical and agrochemical interests. Mitochondrial functions are affected not only in metabolic disorders, but also in cancer and neuro-degenerative diseases including Parkinson and Alzheimer. In addition, drugs targeting the respiratory complex III are used as antimicrobial agents against malaria parasites and phytopathogenic fungi.

Bcs1 Protein

The aim of our group is to dissect the molecular basis of the different steps of mitochondrial biogenesis, including RNA metabolism, translation and OXPHOS complex assembly as well as to study their catalytic mechanisms. Our work and that of others has repeatedly shown that these various processes are intimately linked.

We are especially interested in the nuclear factors involved in these processes, their mechanism of action, and how they can be placed within a network of genetic and biochemical interactions to allow the establishment of a functional respiratory chain and efficient ATP synthesis. To do so, we use a wide range of genetic, molecular, biochemical and biophysical strategies, because the study of the biogenesis and functioning of an organelle requires an integrated view and the use of many complementary experimental approaches.

We work in collaboration with medical laboratories studying mitochondrial dysfunctions in human diseases and we use the yeast models to investigate, at a molecular level, the cause of these defects, to identify new compensatory mechanisms and to search for drugs that could restore the respiratory function.

Keywords

Yeasts, Saccharomyces cerevisiae, Schizosaccharomyces pombe, Mitochondria, Respiratory chain complexes, Mitochondrial gene expression, Yeast genetics, Mitochondrial transformation, Membrane protein biochemistry, Drug screening

Contact


BONNEFOY Nathalie [Senior Researcher - CNRS]
Biogenesis and Functioning of Mitochondrial Oxphos Complexes in Yeasts and Mammals [Leader]
01 69 82 31 75 Gif - Bât 26

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