Date of Award
8-2024
Document Type
Campus Access Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Chemistry/Green Chemistry
First Advisor
Daniel P. Dowling
Second Advisor
Niya Sa
Third Advisor
Marianna Torok, Karen N. Allen
Abstract
Anthropogenic sulfur pollution has contributed to major threats of environmental and human health concerns which only continue to be emitted to the biosphere and disrupt the global sulfur cycle. This dissertation dives into the research surrounding part of a potential response in mitigation and remediation of organosulfur pollutants. Living organisms are able to catabolize a plethora of different compounds, including many pollutants, and the products can be utilized for metabolic processes. Under the bacterial sulfur starvation response, sulfur assimilation pathways enable certain bacteria to intake and breakdown various organosulfur compounds, in part through remarkable and atypical flavoproteins known as two-component flavin dependent monooxygenases. By studying such systems, the potential for application in bioremediation and prevention of emissions of organosulfur pollutants is apparent. The structural and mechanistic studies here represent original knowledge into the incomplete information surrounding the enzymatic degradation of alkanesulfonates of the often-overlooked family of flavin-dependent monooxygenases. Investigations into the alkanesulfonate monooxygenase MsuD yielded crystal structures with various combinations of alkanesulfonates and flavin in different redox states. These structural studies, along with biophysical and functional characterization, confirm MsuD is a homotetramer that acts on short-to-medium length alkanesulfonates and has a structure analogous to other class C flavoprotein monooxygenases. These studies also reveal a novel function for the extended C-terminus of MsuD in catalysis, oligomeric shifts in quaternary state upon ligand binding, and differences in flavin redox state conformations that likely are important for preferred binding of the substrate form, reduced flavin mononucleotide. Through enzyme functional assays, biophysical studies, and the first crystal structures of the MsuD from Pseudomonas fluorescens with and without ligands in different redox states, a wealth of knowledge on MsuD can now be utilized in numerous ways and contributes much to our understanding of two-component flavin dependent monooxygenases.
Recommended Citation
Liew, Jeremy Jun Ming, "Revelations in the Enzymatic Degradation of Alkanesulfonates: Structural and Biochemical Insights into C-S Bond Cleavage from Two-Component Flavin-Dependent Monooxygenases SsuD and MsuD" (2024). Graduate Doctoral Dissertations. 987.
https://scholarworks.umb.edu/doctoral_dissertations/987
Comments
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