Evolution of hybrid genomes

Yeast hybrids harbour in their nucleus the DNA of both parents, however, quite remarkably, they choose to keep the mitochondrial DNA derived from only one of the two parents. The availability of the complete genetic blueprint for all these species and their genetic versatility provide a great opportunity to study molecular evolution of nuclear-mitochondrial incompatibilities. This project aims to study the protein interactions between mitochondrial-generated protein and nuclear-generated proteins, and sets out to understand whether the mitochondria in the hybrid prefers being built using nuclear proteins deriving from the same parent which contributed to their own mitochondrial DNA, in order to ensure efficient cell respiration and avoid incompatibilities. If this is the case, the type of mitochondrial DNA may dictate, during the hybrid evolutionary history, the progressive loss of the mitochondrial proteins generated by the parental nuclear DNA which is less used or does not fit as well onto the mitochondria. We are interested to quantify and map the amount of cross-talk between proteins generated from mitochondria DNA and nuclear DNA in term of fitness of the yeast hybrids. In particular, it is possible to tag or barcode a mitochondrial protein and isolate it together with all the interacting partners, using biochemical (TAP-tagging) and chemical strategies (mass-spectrometry). The interacting proteins identified could either all belong to the same parental species or to both parental types, enabling us to create a protein map of the hybrid mitochondria.