Thursday, November 21, 2024
11/21/2024
Advanced Glycan End Products (AGEs) are toxic and highly reactive dicarbonyl molecules produced by most life on earth from routine metabolic processes. As such, conserved and dedicated detoxifying systems have emerged for dicarbonyl removal. Owing to their importance, these removal systems are required to maintain longevity, thereby emphasizing the importance of dicarbonyl detoxification in maintaining health. One of the most prominent dicarbonyl species is glyoxal, which is predominantly produced as a byproduct of glycolysis. Glyoxal acts by mounting specific attacks on certain amino acids, namely arginines, cysteines, histidines and lysines in key proteins, thereby adversely altering protein function. In humans, these modifications can result in many diseased states, including: cancer, diabetes, nervous system disorders, heart disease, hypertension, atherosclerosis and aging. Unfortunately, although dicarbonyl stress-related toxicity is now regarded as important as oxidative stress, knowledge about how cells are able to detect and respond to glyoxal buildup is, by comparison, severely lacking. Our lab has discovered a novel class of Antibiotic Monooxygenase (ABM) domains that we hypothesize sense and respond to glyoxal and related dicarbonyls from bacteria to humans. This project proposes to elucidate the mechanism by which one of these ABM domains, we named Glyoxal-ABM Domain 1 (GAD1) responds to glyoxal in the bacterial pathogen Pseudomonas aeruginosa. We have thus far shown that GAD1 from P. aeruginosa, which is co- transcribed with the glyoxal detoxification enzyme GloA2, binds heme directly and is also covalently modified by glyoxal on a conserved arginine residue (Arg49). We hypothesize that GAD1 and its many homologs are specifically modified on conserved residues, which, in turn, signals to switch cellular metabolic flux away from glycolysis other pathways unable to produce the glyoxal toxin. Our studies here will Aim to (1) map GAD1 regulation, (2) determine its cellular distribution and its interactome and (3) solve the structures of its apo and holo forms, and in complex with interacting partners in P. aeruginosa. Studying GAD1 in P. aeruginosa is expected to reveal novel pathways that have potential as new antimicrobial targets, and at the same time advance our basic understanding of glyoxal toxicity sensing in humans and other multicellular organisms.
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