Biochemistry, Biophysics, and Structural Biology Commons^™

The Alphaproteobacterial General Stress Response: Investigating Protein Structure, Dynamics, And Regulatory Mechanisms, Danielle Swingle

Dissertations, Theses, and Capstone Projects

Bacteria are relatively simple organisms that face a wide variety of environmental challenges. Their survival is determined by their ability to sense and respond to changes in their surroundings. Alphaproteobacteria commonly accomplish this using the general stress response (GSR). During the first step in this system, a signal is detected by a sensor histidine kinase (HK), modulating autophosphorylation within its kinase domain. HKs involved in the GSR generally belong to the HWE/HisKA2 family, a lesser studied group of HKs with noncanonical features. The signal is propagated when the HK phosphorylates the next protein in the pathway, PhyR. Once activated, PhyR …

Taming Biological Complexity Through The Use Of Symmetries, Luis A. Álvarez-García

Dissertations, Theses, and Capstone Projects

The study of biological systems is, inherently, the study of very complex systems. This is essentially due to the fact that they are made up of numerous, often very complicated, interactions between an extensive number of components. Often necessitating an abundance of quantitative parameters and details for a precise description. The human brain for ex- ample, consisting of ∼ 80 billion neurons with ∼ 800 to 100 trillion connections between them, each of them depending on a large set of parameters. Even simpler examples such as bacterial organisms, such as E. coli and B. subtilis, which we focus on …

The Role Of Secondary And Tertiary Structure In The Cap-Independent Translation Of Fgf-9 And Hif-1-Alpha, Amanda Michelle Whittaker

Dissertations, Theses, and Capstone Projects

Under normoxic conditions, eukaryotes initiate translation of RNA through eIF4E recognition of the 5’ cap. However, under cellular stress, eukaryotic translation must be initiated through a 4E-independent, or “cap-independent” mechanism, involving eukaryotic initiation factor 4G (eIF4G) binding directly to the 5’ untranslated regions (5’ UTR) of the RNA. eIF4G binding then recruits the ribosome to the transcript. While this mechanism is useful for translation of apoptotic transcripts and transcripts involved in cell survival, cap-independent translation is also utilized by oncogenic RNA for tumorigenesis. Previous work by our lab and others has categorized this recruitment and initiation mechanism as either internal-ribosome-entry-site …

Solvation Thermodynamic Mapping Approaches For Computer-Aided Drug Discovery, Vjay Molino

Dissertations, Theses, and Capstone Projects

The drug discovery process is inherently long and costly, prompting the development and integration of computational tools to mitigate these challenges. One of area explored in computer-aided drug discovery is to understand the role of solvation in protein-drug binding and to develop computational tools and methods that can be integrated in the drug discovery process. Grid Inhomogeneous Solvation Theory (GIST) is a tool that provides a framework for mapping solvation thermodynamiproperties of water molecules on the protein surface.This thesis explores the use of GIST in generating pharmacophore models and elucidates the role of solvation in protein structural fluctuations.

One of …

Optimizing Biofilm Assay Reproducibility And Characterizing The 12-Hydroxystearic Acid On Escherichia Coli, Khilola Khusanova

Theses and Dissertations

Biofilm formation in Escherichia coli plays a critical role in microbial chemical communication and surface-associated persistence. This study investigates the antibiofilm activity of 12-hydroxystearic acid (12-HSA), evaluating its R and S enantiomers as well as a racemic mixture. E. coli BL21, biofilms were grown under standardized laboratory conditions and quantified using the Crystal Violet staining assay. Treatment with 12-HSA resulted in a measurable reduction in biofilm biomass, with differences observed between the individual enantiomers and the mixture. These findings suggest that 12-HSA influences early adhesion and biofilm development, supporting its potential as a small-molecule modulator of bacterial surface behavior. This …

Caspases Protect Against Hyperglycemia Induced Necroptosis-Like Cell Death In Brain Endothelial Cells, Aleena S. Mathew

Theses and Dissertations

Acute diabetes characterized by high spikes in blood glucose levels in association with severe hyperglycemia can lead to an increased risk of ischemic stroke in the brain. To better understand high blood glucose levels, hyperglycemia, in the brain we explored its effects on endothelial cells. Endothelial cells line the inner walls of blood vessels and are directly impacted in hyperglycemia. Brain endothelial cells are a major component of the blood brain barrier (BBB) which tightly regulates the brain’s microenvironment. The type of cell death such as apoptosis, caspase dependent, or necroptosis, caspase independent, can exacerbate diabetes associated complications. There is …

Developing Coexpression Systems To Introduce Hydroxyproline Into Protein Engineered Collagen Peptides Utilizing Hydroxylase From Acanthamoeba Polyphaga Mimivirus, Jennifer Soldatich

Theses and Dissertations

A major challenge of developing collagen mimetic peptides (CMPs) by bacterial expression is to include hydroxyproline for biomedical applications. Coexpression of Prolyl-4-hydroxylase from A.mimivirus with CMPs was investigated. Additionally, four expression designs were created for potential applications in mammalian cells to utilize their natural ability of proline-hydroxylation by post-translational modification.

Incorporating Solvation Thermodynamic Mapping In Computer-Aided Drug Design, Yeonji Ji

Dissertations, Theses, and Capstone Projects

Advancements in computational techniques have revolutionized structure-based drug design, substantially improving the efficiency and effectiveness of the drug discovery process by reducing time, costs, and labor requirements. These advancements include various methods, such as investigating small molecule ligands binding to proteins, exploring alternative protein conformations, and solvation mapping on the protein surfaces. Among these methods, understanding the correlation between protein-ligand binding and the role of solvation is important.

A fundamental concept in protein-ligand binding is shape and electrostatic complementarity, which is complicated by the inherent flexibility of proteins. In the absence of small molecule ligands, proteins are complementary to surface …

Guardians Of The Bacterial Genome: Mechanistic Insights Of The Ner Atpase Uvra With Damaged Dnas; Molecular Interactions Between The V.Cholerae Initiator Rctb With Cognate Oricii Dna, Devon Semoy

Dissertations, Theses, and Capstone Projects

Nucleotide excision repair (NER) is one of the fundamental DNA repair pathways in all organisms. A unique facet of NER is the large set of DNA lesions the pathway is capable of repairing (Truglio, Croteau, et al. 2006). The NER proteins may thus be responding to global features of native DNA such as changes in thermodynamic stability, geometry and kinetic properties (Maillard et al. 2007). In this study we set out to investigate the first and primary responder to NER in bacteria, UvrA (Kraithong et al. 2021). UvrA is a homo-dimeric ABC ATPase; proteins that are known to transduce the …

Structural Insights Into Bacterial Helicase Loading At A Replication Origin By Cryogenic Electron Microscopy, Abhipsa Shatarupa

Dissertations, Theses, and Capstone Projects

DNA replication is a meticulously regulated and intricate process crucial for cellular viability. Replicative helicases, essential for unwinding DNA during replication, rely on helicase loader proteins for efficient loading and assembly at replication origins. In Escherichia coli, the replicative helicase DnaB forms a complex with six copies of the bacteriophage Lambda λP loader, resulting in a B₆P₆ conformation. The conformation of the BP complex, with a 6:6 stoichiometry, indicates that the isolated DnaB is initially captured by λP (B₆P₆) through its carboxy-terminal domain lassos/grappling hooks, serving as an early intermediate before transitioning …

Development Of Collagen Mimetic Mini-Fibrils With Tunable Collagenase Susceptibility, Jui Chaugule

Dissertations, Theses, and Capstone Projects

Collagen fibrils are the primary molecular scaffold of all connective tissues and provide the essential support for cell migration and differentiation. Collagen fibrils represent one of the most complex molecular hierarchies: three polypeptide chains in Gly-Xaa-Yaa repeating amino acid sequences, first form the rod-shaped collagen triple helix. These triple helices further self-assemble laterally in a specific manner to form fibrils having the characteristic 67 nm axially repeating structure known as the D-period. Enzymatic digestion of collagen fibrils by matrix metalloproteinases (MMPs) is critical for several physiological processes and is of particular consequence during wound healing. Many of the mechanisms of …

The Epigenetic Impact Of Dietary Choline On Growth Outcomes Of Children Exposed To Gestational Diabetes Mellitus, Ismail Kadam

Dissertations, Theses, and Capstone Projects

Maternal insulin resistance and hyperglycemia lead to gestational diabetes mellitus (GDM) which can cause fetal hyperinsulinemia, ultimately leading to excessive fetal growth associated with macrosomia and increased adiposity at birth. Increased placental macronutrient transport and epigenetic changes in growth and metabolic genes affected by GDM contribute to fetal overgrowth and can result in complications such as overweight/obesity, insulin resistance/type 2 diabetes, cardiovascular disease risk factors, as well as cognitive impairment later in life. Choline, an essential nutrient, participates in lipid and energy metabolism by providing methyl groups for DNA methylation and thus may overcome the hypomethylation of growth and metabolic …

Newly Synthesized Pyroglutamate Amide And Its Neuroprotective Effect Against Neurotoxicity Induced Cell Death In Alzheimer's Disease, Nourelhouda Joutey Elamrani

Dissertations, Theses, and Capstone Projects

The neurodegenerative disorder is an umbrella term for a range of conditions that affects the neurons in the human brain causing neuronal cell death. The common pathway is the excitotoxicity, a phenomenon that describes the toxic actions of excitatory neurotransmitters, primarily glutamate, where the exacerbated or prolonged activation of glutamate receptors starts a cascade of neurotoxicity leading to the cell death. One of the most common neurodegenerative disorders is Alzheimer’s disease (AD), which represents 60 – 70% of cases and it ranked fourth cause of mortality in the USA. In Alzheimer’s disease, glutamate released from astrocytes and activates extrasynaptic N-methyl-D-aspartate …

Exploiting The Heavy Chain Glycans For The Improvement Of Radioimmunoconjugates, Cindy Rodriguez

Dissertations, Theses, and Capstone Projects

Radiolabeled antibodies have become indispensable tools in nuclear medicine. However, the natural roles of antibodies within the immune system mean that they have several intrinsic limitations as a platform for radiopharmaceuticals. A handful of recent preclinical studies suggest that binding by FcR and particularly FcyRI can affect the pharmacokinetic profiles of 89Zr-labeled radioimmunoconjugates. Fc receptors (FcR) are responsible for many of the interactions between immunoglobulins (IgG) and immune cells. In biomedicine, this interplay is critical to the activity of several types of immunotherapeutics; however, relatively little is known about how FcRs affect the in vivo performance of radiolabeled antibodies. Antibodies …

Regulation Of P21 Function By A Sense Long Non-Coding Rna Generated By Alternative Polyadenylation, Anthony Ramadei

Dissertations, Theses, and Capstone Projects

As cells are continually undergoing damage to the genome, a coordinated change in gene expression across thousands of genes is required for the progression of the DNA damage response (DDR). After initial sensing of DNA damage, the transcription factor p53 induces expression of target genes to halt the cell-cycle to allow DNA repair and induce either senescence or apoptosis. One of the p53 target genes is CDKN1A which encodes the cyclin dependent kinase inhibitor p21. p21 halts cell-cycle progression in response to DNA damage and can also induce senescence. However, p21 expression in cancer cells undergoing chemotherapy allows survival by …

Retinoblastoma Malignance And Exosome Mechanisms Facilitating Optic Nerve Head Metastatic Niche Formation, Cui Shi

Dissertations, Theses, and Capstone Projects

Retinoblastoma (RB) is a rare pediatric ocular tumor that occurs before five years of age and it is the most common intraocular cancer of childhood with more than 300 children in the United States and 8000 diagnosed globally each year. RB arises from the proliferation of cone photoreceptor precursor cells in the retina as a result of mutations in the RB1 gene. The influence of RB secreted factors on cells in the retinal environment has not been fully elucidated. Cancer cell released exosomes have been shown to transform their microenvironment through transfer of metastasis promoting molecular cargo. Cancer cell extracellular …

The Seat Of Singular Gene Choice: Dissecting The Role Of Odorant Receptor Enhancer Elements That Lead To Mammalian Olfactory System Expression, Alessandro M. Rosa

Dissertations, Theses, and Capstone Projects

Odorant receptors (ORs) were first identified in 1991 and the initial data strongly suggested that ORs were part of a large superfamily of G-protein-coupled receptors. Within a few years of the discovery of the OR superfamily, it became clear that each OR allele was exclusively expressed in olfactory sensory neurons (OSN), and that this singular expression leads to cellular identity. Many studies over the past thirty years have sought to unlock the mysteries of the mechanism for monoallelic and monogenic OR gene activation and expression in OSNs, however no definitive model for singular gene expression has emerged.

Using a series …

Voltage Set Points For Sodium Channel Inactivation: Intrinsic And Modulatory Mechanisms, Akshay Sharma

Dissertations, Theses, and Capstone Projects

During an action potential, voltage-gated sodium channels (VGSC) control sodium ion flow into the cytoplasm of cells by using membrane voltage to alter channel conformation. These membrane proteins exhibit three main functional conformations: closed, open, and fast-inactivated, with transitions between these states dependent on membrane voltage and kinetics. The channels open within 1 millisecond and swiftly transition from open to fast-inactivated within 1-2 milliseconds following membrane depolarization. Subsequent membrane repolarization resets the channels to the closed state. Notably, even at mildly depolarized potentials that preclude channel opening, VGSCs can undergo transitions between the closed and inactivated states, known as closed-state …

Assessment Of Tripeptides Self-Assembly & Er Stress On Cell Viability And Exosome Secretion In Mda-Mb231, Azmat Parveen

Theses and Dissertations

This study delves into the effects of tripeptides KYpF and WYpK(NBD) on MDA-MB-231 cells, uncovering KYpF's ability to reduce cell proliferation and exosome secretion in peptide treated cells. Conversely, WYpK(NBD) demonstrated significant toxicity at 10 μM. These insights pave the way for optimizing peptide-based cellular treatments for exosome secretion purposes.

Interleukin 24 Induces Apoptosis Through Glycogen Synthase Kinase-3 Beta Inactivation In Prostate Cancer Cells, Sual J. Lopez, Moira Sauane

Theses and Dissertations

Interleukin 24 (IL-24) is a tumor-suppressing protein currently in clinical trials. IL-24 induces cancer-specific apoptosis by activating endoplasmic reticulum (ER) stress and mitochondria dysfunction. We have previously demonstrated that IL-24 leads to apoptosis in cancer cells by protein kinase A (PKA) activation in human breast cancer cells. To further understand the mechanism by which IL-24 induces apoptosis, I analyzed the role of glycogen synthase kinase-3 (GSK3), a highly conserved and normally active serine/threonine kinase in cancer cells and downstream target of PKA. The work reported here provides direct evidence that GSK3 was inhibited following IL-24 treatment in human prostate cancer …

Effect Of Plumbagin On Chemo-Resistant Metastatic Retinoblastoma, John J. Soto

Theses and Dissertations

Retinoblastoma, which is an ocular malignancy, usually results in poor prognoses in pediatric patients worldwide. Retinoblastoma in some events, can develop metastatic phenotypes which can lead to secondary tumor formation, furthering deleterious patient outcomes. It is of paramount importance to identify and research potent novel compounds that can be used to increase the likelihood of remission. Plumbagin (PLB) is a plant-derived, neuroprotective agent, which exhibits significant anticancer activities during in vitro study. PLB has been shown to have a high therapeutic efficacy against chemoresistant sublines as well as their normal counterparts. We attempted to show that the chemoresistant ABCC1 could …

Machine-Learning Qsar-Based Novel Drug Identification To Inhibit Retinoblastoma Extracellular Vesicle Release And Metastatic Signaling, Kunhui Huang

Dissertations, Theses, and Capstone Projects

Extracellular vesicles (EVs) are lipid-enclosed particles that are generated by most types of cells and have been identified as an important mechanism for cell communication aside from cell direct contact. EVs contain a variety of functional macromolecules including proteins, lipids, RNA, which can be transferred from the host cells to target cells at a distance. The molecular pathways of EV biogenesis have been studied intensely in recent decades and the process involves several key genes and proteins. Cancer cell released EVs target distant tissues and upregulate signals that are attractive to cancer cell homing, playing a role in tumor progression …

Development Of Platinum(Iv)-Gold(I)-Based Anticancer Agents, Javier E. Lopez-Hernandez

Dissertations, Theses, and Capstone Projects

Heterometallic compounds have emerged as prospective multitarget anticancer drugs. These species may display improved efficacy and physicochemical properties compared to the individual metallic fragments, while helping combat drug resistance by exerting effects on multiple pathways. In this thesis we describe the synthesis of new bi- and tri-metallic compounds based on platinum(IV) compounds containing FDA-approved platinum agents, and gold(I) derivatives with known anticancer properties. We demonstrate their toxicity and selectivity against a small panel of renal, bladder, ovarian, and breast cancer cell lines, as well as their synergistic effects. We have selected a trinuclear PtAu₂compound containing the Pt(IV) core …

Positron Emission Tomography In Oncology And Environmental Science, Samantha Delaney

Dissertations, Theses, and Capstone Projects

The last half century has played witness to the onset of molecular imaging for the clinical assessment of physiological targets. While several medical imaging modalities allow for the visualization of the functional and anatomical properties of humans and living systems, few offer accurate quantitation and the ability to detect biochemical processes with low-administered drug mass doses. This limits how physicians and scientists may diagnose and treat medical issues, such as cancer, disease, and foreign agents.

A promising alternative to extant invasive procedures and suboptimal imaging modalities to assess the nature of a biological environment is the use of positron emission …

Mechanistic, Biochemical, And Theoretical Studies Of Phototoxicity And Photobluing, Lloyd M. Lapoot

Dissertations, Theses, and Capstone Projects

This thesis consists of four chapters as detailed below:

Chapter 1 discusses the photoconversion of heptamethine to pentamethine cyanines and of pentamethine to trimethine cyanines. Here, we report mechanistic studies and initial experimental evidence for a previously unexplored 4-carbon truncation reaction that converts the simplest heptamethine cyanine to the corresponding trimethine cyanine. We propose a DFT-supported model describing a singlet oxygen (¹O₂) mediated formation of an allene hydroperoxide intermediate and subsequent 4-carbon loss through a retro-Diels-Alder process. Fluorescence and mass spectrometry measurements provide evidence for this direct conversion process. This 4-carbon truncation reaction adds to growing …

Modeling Hydroxide In Classical Proton Hopping Simulations And Amyloid Beta Membrane Pores, Ankita Dutta

Dissertations, Theses, and Capstone Projects

H3O+ and OH- ions display anomalously large diffusion coefficients, a property that is often attributed to their ability to perform structural diffusion which allow these ions to move through aqueous solutions by sequential proton transfers, also known as ‘Grotthuss hopping’. A rearrangement of the local solvation structure is known to be the prerequisite for proton transfer events via these ions. Studying this phenomenon using classical molecular dynamics simulations that do not allow bond rearrangements poses significant obstacles. Here we use a Monte Carlo augmented classical Molecular Dynamics method called the MOBHY algorithm which allows instantaneous changes in protonation states in …

Integrating In Vitro And In Silico Approaches To Gain Insight Into The Mechanism Of Amyloid Fibrillogenesis, Marvin M. Bilog

Dissertations, Theses, and Capstone Projects

Amyloid fibril formation, the hallmark of numerous amyloid-related diseases, has been the subject of a vast number of scientific studies due to its pathological implications. Since the fibrillization process exhibits a certain level of intricacy, its investigation requires a multidisciplinary approach that integrates both experimental and computational methods. In vitro techniques involve biophysical assays and imaging tools for characterizing the structural and kinetic aspects of amyloid fibril formation. In parallel, in silico techniques offer programs for predicting atomistic details and behaviors of amyloidogenic proteins and peptides at the nanoscale level. Serum amyloid A (SAA), human islet amyloid polypeptide (hIAPP), and …

Using Rapid Protein Degradation To Determine The Effect Of Runx1 Loss-Of- Function On Dna Damage Accumulation And Repair., Jackriel Pina Morales

Theses and Dissertations

Germline mutations in RUNX1 are associated with familial platelet disorder with a predisposition to myeloid malignancy (RUNX1-FPDMM), in which patients present with low platelet counts,excessive bleeding and bruising, and an increased risk of Acute Myeloid Leukemia (AML)/Myelodysplastic Syndrome (MDS) development throughout their lifetime. To understand how these loss-of-function mutations in RUNX1 drive predispose to malignancy, it is important to develop a detailed understanding of the molecular basis of RUNX1 function. While RUNX1 is a transcription factor, preliminary data from our group and work from others suggests that RUNX1 also interacts with proteins that are critical for DNA damage …

Towards A New Role Of Mitochondrial Hydrogen Peroxide In Synaptic Function, Cliyahnelle Z. Alexander

Student Theses and Dissertations

Aerobic metabolism is known to generate damaging ROS, particularly hydrogen peroxide. Reactive oxygen species (ROS) are highly reactive molecules containing oxygen that have the potential to cause damage to cells and tissues in the body. ROS are highly reactive atoms or molecules that rapidly interact with other molecules within a cell. Intracellular accumulation can result in oxidative damage, dysfunction, and cell death. Due to the limitations of H₂O₂ (hydrogen peroxide) detectors, other impacts of ROS exposure may have been missed. HyPer7, a genetically encoded sensor, measures hydrogen peroxide emissions precisely and sensitively, even at sublethal levels, during …

A Study Of The Effects Of An Amino Acid Residue On The Thermal Stability Of A Collagen Triple Helix In Varied Sequence Context, Ph, And Ionic Strength Of The Buffer, Zhenxun Xu

Theses and Dissertations

Collagen mimetic peptides are used broadly for collagen research and biomedical applications. Unlike the synthetic peptides obtained by solid phase chemical synthesis, recombinant peptides have more than 100 amino acid residues in length and are expressed in E. coli using designed genes. These longer peptides can offer improved, more native-like functions of native collagen for biomedical applications. One major challenge is the intrinsically low stability of native collagen, which has a melting temperature just above the physiological temperature of the organism. To understand how to enhance the thermostability of the peptides, I investigated the effects of amino acid sequences on …