In this High Risk High Reward DP2 application I wish to investigate the nuclear functions of mitochondrial metabolic enzymes. It is quite evident from current literature that many of the mitochondrial enzymes are localized to the nucleus, more so in diseased conditions such as cancer. However, there is a significant gap in knowledge about their spatial distribution in the nucleus and biological function. We believe nuclear localization of mitochondrial metabolic enzymes is not random, and there is specific necessity coupled to critical biological functions that regulate this process. In this study we wish to perform a comprehensive functional characterization deciphering the spatial and temporal role of mitochondrial enzymes in the nucleus. Our preliminary findings identified Kreb’s cycle enzymes such as aconitase (ACO2), α-keto glutarate (AKG), and citrate synthase (CS); and glycolytic enzymes such as pyruvate dehydrogenase (PDH) and ATP-citrate lyase are enriched in the nucleus of cancer cells. We hypothesize these mitochondrial enzymes form complex in the nucleus based which is yet to be characterized. We hypothesize that they function as a large-multi enzyme complex which is recruited to chromatin by transcription factors and coregulators to sustain metabolic stress encountered during gene transcription. Using metabolomics, proteomics, chromatin immunoprecipitation and gene expression analysis, we envision detailing the sequential events driving their recruitment by nuclear factors on chromatin, and their role in reprogramming transcription machinery to drive aggressive cancer. This is a novel concept supported by isolated reports from various groups, yet remains relatively unexplored and a comprehensive mechanistic study is lacking. We envision findings from our study will have a major impact on broad important problems in biomedical research including metabolic disorders and cancer.