Cells integrate nutrient sensing and metabolism to coordinate proper cellular responses to a particular nutrient source. One way this occurs is via post-translational modifications of proteins. Acetyl-lysine is among the most studied modification and regulates dynamic processes ranging from chromatin and gene expression to metabolism. Our preliminary data presented in this application expand upon the acetylation landscape and describe a new protein modification called acetyl-cysteine. This modification is abundant across the proteome and is enriched on proteins involved in metabolism. These early data reveal key gaps in our understanding of the acetylation landscape: what is the tissue distribution of this new modification? Under which physiological conditions does this modification change? Which proteins are modified? What is the cellular consequence of cysteine hyperacetylation? Is this relevant for aging? There is a critical need to understand the full range of protein modifications in order to better understand physiological nutrient sensing and how it is perturbed in the setting of disease. Although it is widely accepted that lysine modifications can participate in intracellular nutrient sensing and is dysregulated with aging, no data exists on acetyl-cysteine. Therefore, the single objective of this exploratory grant application is to determine the site(s), consequences, and physiologic mediators of cysteine acetylation. Aim 1 will investigate the prevalence of cysteine acetylation by tissue type and metabolic state. In a complementary parallel approach, Aim 2 will characterize the effects of cysteine acetylation on protein activity. This project is significant because it uncovers a previously overlooked protein modification. Furthermore, given cysteine’s central role in redox homeostasis, it is poised to play a central role in metabolic homeostasis. We put forth conceptual and technical innovations that will both follow directed hypotheses and allow unbiased discovery of the most important aspects of this new protein modification. Successful completion of this project will reveal a new aspect of intracellular signaling and metabolic homeostasis that could influence our understanding of redox biology and metabolism during aging.

Post-translational modifications are a well established mechanism of metabolic control. Loss of control is associated with wide-ranging disease states, including the aging process itself. While alterations in protein modifications have been associated with dysregulated metabolism especially in the context of aging, how modifications control metabolism is not known. This key gap in knowledge prevents the generation of effective therapeutics and treatment strategies. Thus, the work described in this proposal is highly relevant to public health because it will determine new mechanisms of action connecting metabolism and nutrient sensing in health and disease.