Periodic Reporting for period 1 - MitoCyto (Mitochondrial Precursor Proteins in the Cytosol as Major Determinants of Cellular Health)
Reporting period: 2022-10-01 to 2025-03-31
Mitochondria are essential organelles of eukaryotic cells. They play pivotal roles in cellular metabolism and ATP production. Mitochondria consist of 900 (yeast) to 1,500 (humans) proteins, most of which are synthesized in the cytosol as precursor proteins. These precursors contain targeting information to direct them to the mitochondrial surface. In most cases, the targeting information is provided by an N-terminal presequence. Presequences bind to receptors on the mitochondrial surface and thread proteins through translocases in the outer and inner membrane of mitochondria. How newly synthesized proteins reach the receptors is not well understood. This step of precursor targeting is of high importance because non-imported precursors are toxic and prevent cell proliferation. The molecular processes that cause these negative effects are not known but it was proposed that non-imported proteins sequester chaperones, bind to and interfere with other proteins and membranes and prevent the efficient protein targeting to other cellular compartments. The main goal of this ERC project is it to elucidate the molecular processes by which non-imported precursors interfere with other cellular processes and how cells neutralize or prevent these harmful effects. A major focus of MitoCyto is it to develop novel technologies that allow it to elucidate the biology of non-imported mitochondrial precursor proteins comprehensively and proteome-wide. These technologies will explore the genetic and the physical interaction networks of mitochondrial precursors and study the relevance of these interactions on a molecular, mechanistic level.
During the first two years of the MitoCyto project, the team was formed consisting of three ERC-funded PhD students, three postdocs (two ERC-funded) and several people paid from university funding. We used thermal proteome profiling to measure the structural stability of the proteins of yeast cells before and after expression of a competitive inhibitor of mitochondrial protein import. This resulted in a comprehensive global overview about the mitochondrial and non-mitochondrial proteins that are affected if the import into mitochondria is competitively inhibited. A study summarizing our observations was published, acknowledging the ERC funding. In total, we published seven publications on MitoCyto-related aspects. All these publications are open-access and they explicitly acknowledge the funding from the European Research Council to the MitoCyto project. Three publications were review articles giving overviews of MitoCyto-related aspects, the other four were original publications showing the first results from the MitoCyto project. Several more publications are in preparation (two are already submitted) or will be written up in the near future. Thus, the MitoCyto project is highly productive and several of the goals described in the applications were already reached or partially reached (see section 1.2 for further details).
The development of novel techniques is a major aspect of MitoCyto. We are working very intensively on these methods. In several cases we already were very successful, with others we are still struggling. See section 1.2 for details.
Thus, in general, the MitoCyto project started very dynamically: The team is largely formed and works the different aspects of the three work packages. We gained quite some visibility for the biology of non-imported mitochondrial precursors and coined this novel and important aspect of molecular cell biology. We are very excited about the MitoCyto project and thank the European Union and the European Research Council for the funding.
Thus, in general, the MitoCyto project started very dynamically: The team is largely formed and works the different aspects of the three work packages. We gained quite some visibility for the biology of non-imported mitochondrial precursors and coined this novel and important aspect of molecular cell biology. We are very excited about the MitoCyto project and thank the European Union and the European Research Council for the funding.