Abigail Lyon | 2024 I.S. Symposium
Name: Abigail Lyon
Title: Elucidating the nicotinic acid degradation pathway in Bacillus niacini: Investigating the catabolic function of a flavin monooxygenase (FMO), domain of unknown function (DUF), and hypothetical protein (HP)
Major: Biochemistry & Molecular Biology
Advisors: Mark Snider; Paul Edmiston (second reader)
Continuous use of pesticides, dyes, and pharmaceuticals leads to the prevalence and buildup of pervasive and toxic compounds in the environment known as N-heterocyclic aromatic compounds or N-HACs. Certain bacteria have evolved to degrade N-HACs as a main source of carbon and nitrogen, therefore reducing the number of carcinogenic compounds found in the environment. The degradation of nicotinic acid (NA) is used as a model system for N-HAC degradation. One aerobic bacterial species, Bacillus niacini, has been shown to degrade NA, but the biochemical pathway in which it does so is not fully elucidated. Within the metabolic operon of B. niacini, three enzymes (FMO, DUF, and HP), have unkown functions within the degradation pathway of B. niacini. This work aimed to identify what these three enzymes accomplish mechanistically in the degradation pathway. Predicted 3D structures of the DUF and HP enzymes showed structural similarities in hydrolase enzymes for DUF and sulfur reduction enzymes for HP. A combination of FMO and HP was able to produce a new intermediate in the B. niacini NA degradation pathway labeled 5,6-DHPip-2-O, which is found in the NA degradation pathway of a fungus, Aspergillus nidulans. Due to the appearance of 5,6-DHPip-2-O in the B. niacini NA degradation pathway, the similarity in fungal NA degradation may suggest a fungal-bacterial association that affected the evolution of B. niacini. Characterizing the enzymes and the chemical transformations they are involved with in the B. niacini pathway presents an opportunity to engineer and use these specific bacteria for more effective and efficient bioremediation purposes to reduce the harmful effects caused by N-HACs.
Posted in Symposium 2024 on April 19, 2024.
