Biochemistry, Biophysics, and Structural Biology Commons^™

Detection And Evaluation Of Hazardous Mercury Contamination In Various Biological Samples, Krish Italiya

Biochemistry and Molecular Biology

Mercury is a toxic environmental pollutant that threatens ecosystems and human health. This study investigates mercury contamination in Lactuca sativa (lettuce) and selected fish species, including tuna and salmon, focusing on plant responses and the limitations of X-ray fluorescence (XRF) analysis. In a controlled experiment, lettuce plants were exposed to mercury to evaluate uptake and toxicity, and XRF spectroscopy was used for quick, non-destructive elemental analysis. Results confirmed mercury accumulation in lettuce, along with visible stress symptoms such as leaf yellowing, purple pigmentation, and tissue damage. Mercury was not detected in tuna and salmon samples, likely due to concentrations below …

Elucidating The Role Of The Rnf20 Histone Modifier In Pancreatic Beta Cells, Tanya Hans Pierre

ETDs from 2020-2029

Diabetes is defined as a loss of functional beta cell mass. It is classically categorized into Type 1 Diabetes (T1D), immune-mediated beta cell destruction and Type 2 Diabetes, which is characterized by whole body insulin resistance alongside beta cell dysregulation. The incidence of diabetes worldwide has risen annually. Despite the presence of therapeutic interventions, diabetes’ heterogeneity can prompt ineffective glycemic control and the development of diabetes-associated comorbidities. For that reason, new approaches to glycemic control for individuals with diabetes are required. One approach to restore glucose homeostasis is beta cell replacement therapy, in which stem cells are programmed into beta-like …

Dock7 Is A Novel Modifier Of Duchenne Muscular Dystrophy Pathology, Katherine English

ETDs from 2020-2029

Duchenne muscular dystrophy (DMD) is a progressive, x-linked neuromuscular disorder affecting 1/5000 male births every year. DMD results from mutations in DMD, a critical structural protein within the muscle. In the absence of Dystrophin, the muscle degrades, increasing inflammation, destabilizing the cell membrane and going through constant cycles of regeneration which depletes the stem cell population. Over time, muscle tissue is replaced by fibrosis and adipose tissue, leading to loss of ambulation, respiratory and cardiac failure leading to death by early 20s. The standard of care for DMD patients is corticosteroid treatment. However, gene therapies have recently emerged which present …

Developing A High-Resolution Off-Axis Common-Mode Digital Holographic Microscope, Lucy Cook

University Honors Theses

Off-axis digital holographic microscopy (DHM) is a powerful tool for 3D, non-invasive live-cell tracking without moving parts. However, traditional setups face an inherent dilemma: split-path interferometers offer high spatial resolution but poor temporal stability, while more stable common-mode configurations are historically limited to lower numerical aperture (NA) regimes. This thesis bridges that gap by scaling a common-mode DHM architecture into a high-resolution benchtop instrument featuring NA = 0.65 objectives, paired with a high-power 520 nm laser source to combat transmission losses and sustain imaging frame rates across an expanded optical footprint. We map the multi-variable design space required to satisfy …

Hydroxamate Formation In The Lipopeptide Containing Siderophore Taiwachelin, Aaron J. Gringer, Kernen P. Agwaza, Isabel Da Fonseca, Pablo Sobrado

Chemistry Faculty Research & Creative Works

Cupriavidus taiwanensis is a nitrogen-fixing bacterium found in root nodules of the invasive tropical weed Mimosa pudica . C. taiwanensis has been shown to grow in environments contaminated with heavy metals such as Pb, Cu, and Cd. Taiwachelin, a recently identified siderophore produced by C. taiwanensis , is an iron chelator that contains a hydroxamate functional group for metal binding. In its biosynthesis, a flavin-dependent N-monooxygenase (NMO) was predicted to hydroxylate l -ornithine, leading to formation of the metal binding hydroxamate moiety. Here, we report the cloning, expression, and biochemical characterization of this enzyme, herein referred to as CtNMO. CtNMO …

Computational Insights Into Nucleosome Dynamics In Epigenetics Using Molecular Dynamics Simulations, Rutika Patel

Dissertations, Theses, and Capstone Projects

Nucleosome core particles (NCP) are the building blocks that form a highly organized and compact chromatin structure. Nucleosomes package DNA in the nucleus of eukaryotic cells. The NCP consists of about 147 base pairs of DNA wrapped around the histone octamer, with 1.65 superhelical turns in a left-handed manner. The histone octamer is composed of two copies of H3, H4, H2A, and H2B. Together with histone H1 and linker DNA, they further assemble into a higher-order chromatin structure. The nucleosome complex is stabilized by electrostatic interactions between positively charged histone residues and the negatively charged DNA backbone. To effectively access …

Mapping Nucleosome Stability: Linking Oncogenic Structural Alterations To Long-Range Allosteric Communication, Augustine C. Onyema

Dissertations, Theses, and Capstone Projects

The nucleosome core particle (NCP) is essential for chromatin structure and function, serving as the fundamental unit of eukaryotic chromatin. Oncogenic mutations in core histones disrupt chromatin dynamics, altering DNA repair and transcription processes. How DNA communicates with histones, and how this information propagates through the histone, has been suggested to be a cooperative process. Here, I investigate the molecular consequences of two mutations, H2BE76K and H4R92T, using 36 µs of all-atom molecular dynamics simulations on Anton2. I also characterize the kinetic correlation within histone/DNA domains via conditional activity (CONDACT) using the dihedral angle as our degrees of …

Identifying Textual Predictors Of Early Termination In Clinical Trials In Medicine: An Explainable Machine-Learning Study, Rohan Ramnarain

Dissertations, Theses, and Capstone Projects

About one in five clinical trials in medicine ends early, wasting valuable resources and reducing the evidence available for developing life-saving medical treatments. This project uses a method called Trial2Vec, which is a self-supervised machine-learning method that converts clinical trial documents into dense numerical representations that capture their key design and clinical characteristics, to turn each proposed clinical trial’s written protocol into a compact numerical profile (a process referred to as embedding). These profiles are then paired with a predictive machine learning models to identify the words and phrases in the trial documents that can signal a higher risk of …

Supramolecular Assembly In Short Peptide Systems For Selective Metabolite Recognition And Drug Nanoencapsulation, Maithreyi Ramakrishnan

Dissertations, Theses, and Capstone Projects

Short peptides can form adaptive supramolecular assemblies, and understanding how minimal sequences organize around neurometabolites or hydrophobic cancer drugs enables the rational design of functional materials. This thesis combines molecular dynamics with experimental validation to establish design rules linking peptide sequence to emergent structure and function. Chapter 1 outlines the molecular determinants governing peptide assembly. Chapter 2 reviews computational workflows that reveal sequence-dependent conformations and supramolecular organization. Chapter 3 applies these principles to Dynamic Peptide Libraries which identify tetrapeptides that selectively interact with neurometabolites. Chapter 4 extends the same interaction-driven framework to design tryptophan-rich pentapeptides that co-assemble with kinase inhibitors …

Immunomodulatory And Signaling Molecules From Plant-Associated Bacteria: Toll-Like Receptor 4 Agonist Adjuvants And Diketopiperazine-Mediated Communication, Marian Romaine

Dissertations, Theses, and Capstone Projects

Medicinal plants and their associated microbiomes constitute a rich source of bioactive natural products with applications in immunotherapy and microbial ecology. Herbal formulations have long been valued for safe immune enhancement, while bacterial signaling molecules govern community behaviors critical to pathogenesis, symbiosis, and environmental processes. Bacterial lipopolysaccharides (LPS) from plant-associated Gram-negative bacteria have emerged as potent TLR4 agonists, yet their endotoxic potential limits direct use, and diketopiperazines (DKPs) serve as versatile quorum-sensing mediators capable of modulating biofilms in mixed microbial systems.

The work in this thesis comprises two independent but complementary research strands. The first strand pursued the engineering of …

Structure Of Ergosteryl-Aspartate Synthase Reveals How An Entrapped Trna Is Used Like A Prosthetic Swinging Arm In The Synthesis Of Aminoacylated Sterols, Hanako Murayama, Nathaniel Yakobov, Nassira Mahmoudi, Sasha Legrosdidier, Nicolas Fournier, Solène Zuttion, Kanata Matsumoto, Michihiro Nishimura, Jingwei Ji, Bruno Senger, Laurence Huck, Howard Gamper, Yoshiaki Kise, Ralph Kleiner, Mathieu Frechin, Ya-Ming Hou, Hubert Becker, Yuzuru Itoh, Frédéric Fischer, Osamu Nureki

Department of Biochemistry and Molecular Biology Faculty Papers

Ergosteryl-3β-O-L-aspartate synthase (ErdS) catalyzes tRNA-dependent aspartylation of ergosterol, a lipid essential for fungal cell membrane integrity. However, the functional significance of ergosteryl-aspartate and the molecular mechanisms underlying its synthesis remain unclear. Here, we show that ErdS localization is highly dynamic and that Erg-Asp is required for proper hyphal growth, sporulation, and spore germination, and likely influences stress tolerance. The cryo-electron microscopy structure of ErdS revealed an unprecedented sterol-binding pocket. In addition, the structures in complex with a non-hydrolyzable Asp-N-tRNAAsp show a tRNA-guided intramolecular aminoacyl transfer mechanism between two functional domains of the enzyme. The CCA end of tRNAAsp undergoes a …

High-Throughput Robotic Ethanol Inhibition Assays For Engineered Thermophilic Biofuel Strains, Kevin He, Daniel Olson, Marybeth Maloney, Anthony Lanahan

Wetterhahn Science Symposium Posters

Ethanol stress assays are commonly used to evaluate microbial tolerance, metabolic adaptation, and fermentation performance. However, manual liquid handling introduces variability across replicate wells and small-volume pipetting steps, limiting reproducibility and throughput. This study developed an automated OT-2 robotic workflow to generate replicated ethanol concentration gradients for high-throughput inhibition assays in engineered thermophilic biofuel strains. Kinetic plate-reader measurements were used to quantify ethanol-dependent growth responses under anaerobic fermentation conditions. The reasearch question is: How do engineered thermophilic biofuel strains differ in ethanol-dependent growth inhibition under anaerobic fermentation conditions, and can automated robotic assays improve the reproducibility of these measurements? Can …

Somatic Prosthetics For Planetary Resonance, Disha Dharesh Kumar R

Masters Theses

This thesis investigates how industrial design can transcend extractive technological paradigms in favor of relational interfaces that foster planetary attunement. Framing the climate crisis as a 'crisis of imagination', the research challenges the Western bifurcation of nature and culture by drawing on Indic cosmologies- which recognize stones, plants, and ecosystems as conscious at different levels and participants in a shared cosmic field. By synthesizing research in Biosemiotics, Quantum Information Pansycishm, and Neuroscience, the project redefines intelligence as a distributed, more-than-human phenomenon.

The research materializes as a speculative design artifact: a device that functions as a somatic prosthetic for planetary resonance. …

Crystal Structure Of Mouse Dxo In Complex With The Udp-N-Acetylglucosamine Cap And Molecular Mechanism For The Decapping Reactions, Najeeb Ullah, Selom K. Doamekpor, Liang Tong

Department of Biochemistry and Molecular Biology Faculty Papers

Noncanonical metabolite 5' caps have recently been identified on RNAs, and the DXO/Rai1 family of enzymes can remove these caps in eukaryotes. While the binding modes of NAD, FAD and dephospho-CoA (dpCoA) caps in the active site of mouse DXO have been determined, how DXO recognizes the UDP-glucose (UDP-Glc) and UDP-N-acetylglucosamine (UDP-GlcNAc) caps is not known. In addition, the molecular mechanism by which DXO catalyzes the decapping reactions is still poorly understood, especially the location of the water/hydroxide that attacks the scissile phosphate to initiate the decapping. Here we report the crystal structure of mouse DXO in complex with UDP-GlcNAc …

Combating Β-Lactamase Resistance: From Inhibitor Design To Substrate Evolution, Lian M.C. Jacobs

USF Tampa Graduate Theses and Dissertations

β-lactamase production by bacteria is a major mechanism of antibiotic resistance. These enzymes hydrolyze β-lactam antibiotics, preventing them from binding to and inhibiting PBPs. Although new β-lactam scaffolds and inhibitors are continually introduced into the clinic, resistance often emerges within a few years. Therefore, the development of cross-class inhibitors with novel scaffolds is critical to mitigate this resistance. In parallel, a deeper understanding of the structural and mechanistic basis of β-lactamase resistance is essential. Together, these approaches provide an effective strategy for combating antibiotic resistance.

The first project addressed the need of effective cross-class β-lactamase inhibitors capable of targeting SBL …

The Heterogeneous Response Of Astrocytes In Different Brain Regions Under Metabolic Stress, Pawan Kumar Thapaliya

USF Tampa Graduate Theses and Dissertations

Astrocytes play a central role in maintaining ionic homeostasis, neurotransmitter clearance, and brain en-ergy metabolism. Their excitability, reflected in activity-evoked intracellular sodium (Na+, [Na+]i) and calcium (Ca2+,[Ca+]i) dynamics, is increasingly recognized as a critical determinant of neuronal function and vulnerability, particularly under metabolic stress. Despite their importance, the mechanisms underlying astrocytic ionic signaling and its regional heterogeneity remain incompletely understood. In this thesis, I developed detailed computational and biophysical models to investigate astrocytic Na+ and Ca2+ dynamics, their bioenergetic consequences, and the roles of key ion transporters under physiological and metabolically stressed conditions, validating the models against experi- mental data. …

In Vitro Reversal Of Abc Transporter Mediated Multidrug Resistance In Human Ovarian And Non-Small Cell Lung Cancer Models, Alison K. Kellom, Pia D. Vogel

Biological Sciences Theses and Dissertations

One of the major causes of treatment failure in aggressive cancers is multidrug resistance (MDR), which is linked to the overexpression of membrane efflux proteins that export chemotherapeutics from cancer cells. This mechanism prevents chemotherapeutic drugs from reaching cytotoxic concentrations intracellularly, allowing the cancer to survive. Two primary mediators of this mechanism are P-glycoprotein (P-gp) and Breast Cancer Resistance Protein (BCRP). P-gp and BCRP are transmembrane ATP-binding cassette (ABC) transporters that are frequently overexpressed in MDR cancers. They utilize the binding and hydrolysis of ATP to transport a diverse range of amphipathic molecules of varying size (Schinkel and Jonker, 2003), …

Microtubules In Breast Cancer: Exploring The Α/Β-Tubulin Toggle Switch And Its Implications In Human Breast Cancer, Annemarie Ianos

Student Theses and Dissertations

Microtubules, composed of a/b-tubulin heterodimers, play a central role in breast cancer tumor growth by polymerizing, leading to metastasis and depolymerizing, contributing to proliferation. Human enzymes protein kinase Ca (PKC-a) and cyclin-dependent kinase 1 (Cdk-1) mediate phosphorylation at sites a:Ser165 and b:Ser172, respectively, influencing the growth of microtubules. It is possible that alternating phosphorylation at these sites contribute to an a/b-tubulin “toggle switch” that mediates microtubule instability and tumor growth.

The project investigates the influence of the toggle switch model on microtubule stability by determining the impact of mutants (a:S165D, a:S165N, a:S165S_P, b:S172S_P and a:S165S_P/b:S172S …

Computational Design Of Peptides And Proteins Through Machine Learning Approaches, Emily J. Hendrix

Chemistry and Chemical Biology ETDs

Advancements in machine learning have emerged as a pivotal tool in computational biochemistry, offering new advancements to address challenges in protein structure and function. However, current machine-learning approaches offer limited insight in understanding protein dynamics. The purpose of this work is to combine traditional physics-based computational tools, such as molecular dynamics and coarse-grained simulations, with recently developed AI-driven computational tools to bridge gaps and advance the understanding of proteins in both structural and dynamic aspects. I investigated several approaches such as (i) traditional physics-based methods to study protein conformation and ensembles; (ii) identifying a peptide inhibitor for the PICK1 PDZ …

Virus-Like Particle Peptoid Conjugate As A Triple-Negative Breast Cancer Targeting Delivery System, Ricky Zhu

Chemistry Theses

Triple-negative breast cancer (TNBC), an aggressive form of breast cancer, characterized by its lack of estrogen receptors (ER), progesterone receptors (PR), and human epidermal growth factor receptors (HER2) poses a therapeutic challenge as common treatment options are rendered ineffective. Here is a strategy to develop a drug delivery system utilizing poly-glycinated LC129 8, a TNBC targeting peptoid, covalently attached to HK97 virus-like particles (VLP) containing a C-terminal LPETG sequence via a sortase mediated reaction. Using the properties of the cage-like structure of VLPs and the TNBC specificity of the LC129-8, high doses of chemotherapy can be efficiently loaded into the …