Project Details
Projekt
The contribution of cytosolic chaperones to the biogenesis of mitochondrial proteins
Subject Area
Biochemistry
Term
since 2024
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 541647314
Most mitochondrial proteins are encoded by the nuclear genome and are imported into mitochondria after synthesis on cytosolic ribosomes. Accordingly, they face the challenge of maintaining an import-competent conformation in the cytosol. This is particularly crucial for those precursor proteins that contain hydrophobic segments, like stretches that will integrate into a mitochondrial membrane. Such exposed hydrophobic regions make these proteins vulnerable to aberrant interactions and aggregation. Therefore, cytosolic factors bind newly synthesized preproteins on their way to mitochondria and thus counteracting aggregation, degradation, and misfolding. Despite the progress made in recent years, we are still missing a comprehensive picture of the complete repertoire of factors that associate with mitochondrial proteins during their passage through the cytosol and mechanistic insights into the roles of individual factors are still absent. In this proposal, we aim to fill this gap by merging the expertise of our two labs, proven over several productive collaborations to be a strong combination. We will address two main aims that are led each by one group but strongly supported by the other one: Aim 1: Define the chaperone interactome of different mitochondrial proteins en route to the mitochondria (led by the Rapaport group). Aim 2: Investigate the interactions of the various (co)chaperones with mitochondrial precursor proteins (led by the Buchner group). To achieve Aim1 we will perform both pull-down assays and proximity labeling followed by mass spectrometry. Next, newly identified factors will be validated by a variety of functional assays. In the framework of Aim 2, we will analyze in detail using a broad spectrum of techniques the interactions of chaperones with mitochondrial precursor proteins under various conditions. Known chaperones as well as newly identified factors will be included in these assays. The involvement of import receptors in this process will be also investigated. In summary, the proposed projects will reveal a comprehensive picture of the chaperoning of preproteins on their way through the cytosol to the mitochondria. We envision this to be performed by a core (co)chaperone machinery complemented by additional factors in a preprotein-specific manner. We will also obtain information whether the release of the chaperones as part of the transfer of the protein to the import pore is a regulated process involving the import receptors.
DFG Programme
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