SUMMARY Mitochondria function as the powerhouses of the cell and are essential to cellular and organismal health. Conversely, mitochondrial degeneration and dysfunction are hallmarks of human diseases including developmental and metabolic disorders, type 2 diabetes, Alzheimer's disease, Parkinson's disease, Huntington's disease, cancer, atherosclerosis, and cardiovascular diseases. Consequently, several surveillance strategies have evolved consisting of molecular chaperones and energy-dependent proteases that protect mitochondria from damage. Mitochondria possess a representative member of every stress-inducible chaperone family; thus, providing a paradigm to elucidate the function of the ensemble of molecular chaperones in proteostasis maintenance. It is widely appreciated that molecular chaperones provide the first line of defense against protein misfolding by promoting the correct folding and preventing aberrant folding and aggregation. Mitochondrial chaperones are also widely expressed in most tumor cell types, including colorectal, breast, prostate, and ovarian cancer, which have the highest mortality rates, indicating a central role of mitochondrial chaperones in the immortalization of cancer cells and underscoring their significance as promising anti-cancer drug targets. The broad and long-term research objective is to provide a molecular understanding how mitochondrial chaperones maintain proteostasis under physiological conditions and how their function is modulated in pathological states. Specifically, we will focus on the structural analysis of a novel ATP-dependent mitochondrial chaperone using X-ray crystallography and cryoEM, determine its protein interactome using functional proteomics, and use a structure-guided mutagenesis approach to elucidate its biological function in vitro and in living cells. Addressing an important biomedical problem using a multi-pronged approach at different resolution and time scale underscores the significance and impact of the proposed research.

RELEVANCE Mitochondrial dysfunction is a root cause of developmental and metabolic disorders, cancer, and aging-related neurodegenerative diseases. While molecular chaperones provide the first line of defense against protein misfolding and aggregation, their function (or lack thereof) in disease states remains poorly understood. The broad and long-term research objective is to provide a molecular understanding of how mitochondrial protein quality control machines protect the organelle from damage and to exploit this information for the development of new therapeutic strategies against unmet human diseases.