Biochemistry, Biophysics, and Structural Biology Commons^™

Nanoscale Morphological Perturbations Of Lipid Membranes Induced By Membrane Active Peptides, Yasith Sandeepa Indigahawela Gamage

USF Tampa Graduate Theses and Dissertations

Membrane-active peptides (MAPs) are a diverse group of biologically relevant molecules that induce nanoscale modulations during their interactions with cell membranes. Understanding the precise mechanism by which these MAPs perturb or modulate the cell membranes is a cornerstone of membrane biophysics, as it facilitates rational design of useful therapeutics. That is, if we have the knowledge to determine what the peptide can do, how selective it is, or how toxic it might be, we can optimize them and design new peptide therapeutics such as for antimicrobial, anticancer, or drug-delivery applications. In general, MAPs can be categorized into two classes based …

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. …

The Molecular Determinants Of Deglycation And Substrate Specificity In Fructosamine Kinases, Jenet Matlack

USF Tampa Graduate Theses and Dissertations

Protein glycation is a universal, non-enzymatic modification that occurs when a sugar covalently attaches to a primary amine. These spontaneous modifications may have deleterious or regulatory effects on protein function, and their removal is mediated by the conserved metabolic kinase fructosamine-3-kinase (FN3K). Despite its crucial role in protein repair, we currently have a poor understanding of how FN3K engages or phosphorylates its substrates. Additionally, the molecular basis for the distinct yet overlapping substrate specificities of FN3K and its paralog, ketosamine-3 kinase (KT3K), remains unresolved. By integrating structural biology, biochemistry, and ancestral protein reconstruction (APR), this thesis elucidates the catalytic mechanism …

The Role Of Fkbp51 In The Regulation Of Reproductive Aging And Prenatal Stress-Impaired Ovarian Function And Development, Monica C. Moore

USF Tampa Graduate Theses and Dissertations

FK506-binding protein 51 (FKBP51) is an immunophilin that acts as a co-chaperone with heat shock protein 90 that negatively regulates transcriptional activity of glucocorticoid receptor (GR) and progesterone receptor (PR), and FKBP51 levels are increased by stress conditions. Our previous studies demonstrate that Fkbp5 gene depletion was protective against maternal re-strained stress-induced preterm birth (PTB), fetal growth restriction (FGR), and maternal stress-induced age-related decline in live births. We hypothesize that FKBP51 contributes to impaired ovarian development and folliculogenesis induced by prenatal stress (PNS). Timed-pregnant Fkbp5+/+ (wild-type) and Fkbp5−/− (knockout) mice were randomly assigned to either the undis-turbed (nonstress) or PNS …

A Bioarchaeological Study Of The Individuals From The Városfalva Burial Mound In Transylvania, Romania (15th-19th Century), Vanessa C. Reeves

USF Tampa Graduate Theses and Dissertations

This study explores the lives and deaths of the Szekler people recovered from a burial mound in the Transylvanian village of Városfalva. The Transylvanian plateau is located in present day Romania, and is protected on the east and the south by the Carpathian Mountains. The Szekler people arrived in this area around 1000 CE, and were a nomadic group originating in the Asian Steppes region who later intermarried with various migratory groups as they moved across the Eurasian plains. The Szeklers eventually banded together with the proto-Hungarian Magyar peoples and settled in the Carpathian Basin, the easternmost frontier of the …

Parameterizing Ion–Lipid Interactions From Local Clusters To Reproduce Experimental Bulk Properties Of Lipid Bilayers, W. Matthew Saunders

USF Tampa Graduate Theses and Dissertations

Phospholipids are the main component of cell membranes, providing a delimiting boundary for cells from their environments or from their organelles from the cytosol. Thiscompartmentalization allows cells to maintain quite different solutions within their cells and organelles, including different mixtures dissolved ions. Consequently, these membranes are constantly flanked by complex mixtures of salts at varied concentrations. To study membrane structure, one cannot neglect the contribution of the salts in the local solution. Ions perturb bilayer structure via specific interaction with the phospholipids, primarily with the headgroups. Experimental studies of these systems are somewhat at odds — scattering experiments with different …

Improving Coral Restoration Outcomes Through Novel Molecular Applications, Matthew H. Gamache

USF Tampa Graduate Theses and Dissertations

Coral reef ecosystems are declining globally from numerous stressors, including localized pollution, disease, and marine heatwaves induced by climate change. To preserve these ecosystems, it is critical to identify corals that can withstand stressors—primarily future marine heatwaves—and prioritize them for coral restoration efforts until these stressors are mitigated. Coral responses to thermal stress can be influenced by several partners, including mutualistic microalgae and a vast prokaryotic community. Here, I use advanced molecular techniques to examine which partners (coral host, algal symbiont, and microbial communities) are associated with coral health, how they contribute to holobiont physiology, and their potential to increase …

Dnajb6: A Potent Dnajb Chaperone In Regulating Tau Proteostasis, Abigail R. Esquivel

USF Tampa Graduate Theses and Dissertations

Neurodegenerative diseases often feature the pathological buildup of misfolded proteins, and tau is a principal culprit in multiple tauopathies. One chaperone of emerging interest is DnaJB6b, a member of the Hsp40/DnaJ family, which exhibits potent anti-aggregation activity against several disease-related proteins. Recent investigations highlight its unique capacity to recognize and neutralize aggregation-prone forms of tau. DnaJB6b appears potent against multiple variants of tau and may be acting against tau, in part, by directing misfolded tau toward proteasomal clearance. The first lines of evidence come from systematic chaperone screens, where DnaJB6b repeatedly emerged as a strong suppressor of tau seeding. Further …

Γ -Aapeptides Targeting Amyloid-Β Pathway And Neural Repair For Alzheimer’S Disease Treatment, Ning Shen

USF Tampa Graduate Theses and Dissertations

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the accumulation of amyloid-beta (Aβ) plaques and progressive neuronal degeneration. Despite extensive research, no treatments have been able to effectively halt or reverse the progression of the disease. This study aimed to evaluate the therapeutic potential of two novel γ-AApeptides, HW-C9 and 125-6b, in AD treatment, assessing both their individual and combined effects. HW-C9 was designed to inhibit Aβ aggregation, while 125-6b was developed to promote neuronal growth and repair. Initially, the therapeutic effects of HW-C9 and 125-6b were assessed both in vitro and in vivo. The results showed that HW-C9 …

A Phenotypic Characterization Of Staphylococcus Aureus Bacteremia Clinical Isolates, Sara Dj Daniels

USF Tampa Graduate Theses and Dissertations

Staphylococcus aureus is a human pathogen of serious concern because of its ability to cause serious and wide-ranging disease. Of particular concern is the ability of S. aureus to cause bacteremia (SAB), allowing the bacteria to disseminate and spread to various organs. This study addressed this issue through the phenotypic characterization of two methicillin-resistant S. aureus (MRSA) clinical isolates taken from patients with sustained complicated bacteremia at Tampa General Hospital, referred to as SA1097 and SA1098. A battery of phenotypic tests was conducted on these strains, including a growth curve, hemolysis and proteolysis screenings, cytotoxicity assays using human neutrophils, blood …

Rictor, A Mtorc2 Protein, Regulates Lymphatic Valve Formation And Maintenance Through The Akt-Foxo1 Signaling Axis, Richa Banerjee

USF Tampa Graduate Theses and Dissertations

The lymphatic vasculature maintains tissue fluid homeostasis by absorbing interstitial fluid to form lymph and transporting it back to the bloodstream. Collecting lymphatic vessels have lymphatic valves (LVs) that prevent the retrograde flow of lymph generated by hydrostatic pressure from the blood vasculature. Backflow and accumulation of lymph leads to a lymphatic pathology called lymphedema. This implicates the involvement of defective LVs in the pathogenesis of lymphedema and warrants the study of lymphatic valve development and maintenance. The LVs are formed through a process called mechanotransduction which signals through the intracellular PI3K-AKT pathway in lymphatic endothelial cells. However, the activation …

Selective Pericyte Recruitment To Ec-Lined Tubes, Vessel Assembly Enhancement Through Pericyte Timp-3 Induction, And Pericyte Tbx2 In Capillary Formation And Maturation, Ksenia Marilyn Yrigoin Kaluguina

USF Tampa Graduate Theses and Dissertations

Capillaries, the smallest blood vascular networks, are formed by narrow and elongated endothelial cell (EC)-lined tubes with associated pericytes anchored to the abluminal tube surface. Our laboratory demonstrated that dynamic interactions between ECs and pericytes during capillary tube network assembly are required for basement membrane matrix deposition and maturation. We have also shown that key EC-derived factors promote pericyte recruitment, proliferation, and pericyte-induced basement membrane formation during capillary assembly. In the first section, we aim to identify if vascular smooth muscle cells (VSMCs) respond to the same factors and have the same invasive ability as pericytes since they are both …

Exploring Biosignatures And Biogeochemical Processes In Lanzarote Lava Tubes: Implications For Martian Analog Research, Vera Palma, Ana Z. Miller, Francesco Sauro, Bogdan P. Onac, José M. De La Rosa, Sara Gutiérrez-Patricio, Beatriz Cubero, José A. Gonzalez-Perez, Jesus Martínez-Frías, A Teresa Caldeira

FRONTIERS UNBOUND: Exploring Extreme Environments

No abstract provided.

Exploring Pristine Microbial Ecosystems From The Uninhabited Volcanic Selvagens Islands, Pedro N. Jiménez-Morillo, Sara Gutiérrez-Patricio, Vera Palma, Ana Teresa Caldeira, Nicasio Tomás Jiménez-Morillo, Ana Z. Miller

FRONTIERS UNBOUND: Exploring Extreme Environments

No abstract provided.

Malat1 Mediates Tet2 Loss Of Function-Driven Oncogenic Inflammation Via Rna Shielding Of Nf- Kappa B P65, Nana Adjoa Ben-Crentsil

USF Tampa Graduate Theses and Dissertations

TET2 is a dioxygenase that regulates gene expression and hematopoiesis by oxidizing 5-methylcytosine residues on DNA to 5-hydroxymethylcytosine. TET2 mutations are common genetic events in hematological disorders. For example, TET2 is the most frequently mutated gene in Chronic Myelomonocytic Leukemia and occurs in about 33% of other myeloid malignancies. It is also the second commonest mutation in clonal hematopoiesis of indeterminate potential (CHIP), a common premalignant condition in the elderly. TET2 mutations arise in founding clones and are implicated in many non-hematological sequelae seen in CHIP like atherosclerotic disease, chronic liver disease, and severe microbial infections.

The development of TET2-deficient …

Heparan Sulfate Roles In Amyloid-Beta Clearance And Alzheimer’S Disease Pathogenesis, Ilayda Ozsan

USF Tampa Graduate Theses and Dissertations

Alzheimer's disease (AD) is the most common form of dementia yet remains without an effective treatment due to its poorly understood etiology. Mounting evidence points to the accumulation and aggregation of amyloid-β peptides (Aβ), which constitute amyloid plaques in the brain, as pivotal in initiating and accelerating AD pathogenesis. Extensive efforts have focused on uncovering the molecular underpinnings and fundamental origins of impaired Aβ metabolism in AD. Heparan sulfate (HS), a linear polysaccharide of the glycosaminoglycan family, co-deposits with Aβ in plaques within the AD brain. It directly binds to and accelerates Aβ aggregation, interacts with key players in Aβ …

Roles Of Mitochondrial Chchd2 And Gpcr-Associated Β-Arrestin2 In The Pathogenesis Of Lewy Body Disorders, Teresa R. Kee

USF Tampa Graduate Theses and Dissertations

Coiled-coil-helix-coiled-coil-helix domain containing 2 (CHCHD2) is a mitochondrial protein that plays important roles in cristae structure, oxidative phosphorylation, and apoptosis. Multiple mutations in CHCHD2 have been associated with Lewy body disorders (LBDs), such as Parkinson’s disease (PD) and dementia with Lewy bodies (DLB), with the CHCHD2T61I mutation being the most widely studied. We generated the first transgenic mouse models expressing human CHCHD2WT and the PD-linked CHCHD2T61I mutation driven by the mPrP promoter. CHCHD2T61I Tg, but not CHCHD2WT Tg mice exhibit perinuclear mitochondrial aggregates, neuroinflammation, and have impaired long-term synaptic plasticity associated with synaptic dysfunction. Dopaminergic neurodegeneration, a hallmark of PD, …

Functional Studies Of Dcaf14 In Replication Fork Stability And Genome Integrity, Neysha Tirado-Class

USF Tampa Graduate Theses and Dissertations

The response to replication stress is critical for ensuring the stability of replication forks and preserving genome integrity. To aid this response, several factors are recruited to stalled replication forks to prevent irreversible collapse of the replication machinery. Replication fork proteomic analyses of stalled forks reveal enrichment of DCAF14, a component of the Cullin4-RING (CRL4) E3 ubiquitin ligase complex, that mediates replication fork protection by blocking nuclease-mediated digestion of nascent DNA. However, little is known about the molecular mechanism by which DCAF14 functions in the context of replication stress. Notably, loss of function mutations in DCAF14 are associated with a …

Group B Streptococcus Intestinal Barrier Disruption And The Protective Role Of Butyrate, Kristen Dominguez

USF Tampa Graduate Theses and Dissertations

Group B Streptococcus (Streptococcus agalactiae; GBS) is a leading cause of neonatal sepsis worldwide. Intrapartum antibiotics in GBS-colonized mothers significantly reduced the incidence of early-onset sepsis occurring in the first week of life; however, there are currently no prophylactic interventions for late-onset sepsis, occurring within the first 3 months of life. GBS is a pathobiont that primarily colonizes the gastrointestinal tract and can cross the intestinal barrier via both the paracellular and transcellular routes, causing invasive disease. Neonatal susceptibility to GBS intestinal translocation is mediated by inadequate epithelial barrier function and microbiome immaturity; however, the mechanisms by which GBS exploits …

Cornus Officinalis Extract Activates The Keap1/Nrf2 Pathway And Delays T1d Onset In The Nod Mouse, Justin D. Fletcher

USF Tampa Graduate Theses and Dissertations

Type 1 diabetes (T1D) is an autoimmune disorder that results in the destruction of the insulin producing pancreatic β cells. The only therapeutic option following T1D clinical onset is exogenous insulin supplementation. At present, there is no cure for T1D and attempted interventional therapy has been focused on modulating the immune system. Few attempts have been pursued at preserving β cell function and survival. Here we provide a novel approach using extract from the fruit of the Cornus officinalis (CO) tree to preserve β cell function through the prevention of β cell stress. CO has been used in traditional Chinese …

Investigation Of Self-Assembly Of Hen Egg White Lysozyme Fibrils, Nabila Bushra

USF Tampa Graduate Theses and Dissertations

Amyloid proteins are a large group of proteins that tend to aggregate and form insoluble fibrils with a characteristic cross-β sheet structure. Intriguingly, this process of “amyloid formation” has been simultaneously linked to devastating human diseases called amyloidoses, ranging from Alzheimer’s Disease, cardiac amyloidoses to type II diabetes, as well as functional biological responses such as hormone storage and sperm quality control. Amyloid fibrils have also attracted significant attention for their unique mechanical, chemical, and optical characteristics, establishing them as promising tough biomaterials. The urgent need to find treatments for Alzheimer’s disease, and the demand for safe and renewable biomaterials …

Macrophage-Driven Car T Cell Resistance In B Cell Lymphoma, Sae Bom Lee

USF Tampa Graduate Theses and Dissertations

Chimeric antigen receptor (CAR) T-cell therapy has revolutionized the treatment of patients with relapsed/ refractory large B cell lymphoma (LBCL). Despite its promising efficacy, a subset of patients experiences primary resistance or relapse. In Chapter 2, we explore the tumor microenvironment (TME)-induced resistance mechanisms in patients with LBCL. Analysis of the intratumoral immune infiltrates in pre-infusion tumor biopsies revealed that the levels of immunoregulatory macrophages were elevated in patients who responded poorly to axicabtagene ciloleucel (axi-cel). Using preclinical mouse B cell tumor models, we found that the CAR T-cell-produced interferon-gamma (IFN-γ) enhanced the expression of inducible nitric oxide synthase (iNOS, …

Tetr Family Regulator, Farr, Influences Rot-Mediated Control Of Virulence Factor Expression In Staphylococcus Aureus, Julia C. Schumacher

USF Tampa Graduate Theses and Dissertations

Point-mutation variants of the TetR family regulator, FarR, have emerged across Staphylococcus aureus sequence types as conferring antibiotic and fatty acid resistance, particularly in Hospital-Associated Methicillin Resistant S. aureus (HA-MRSA) strains. FarR also exhibits an additional largely uncharacterized relationship to virulence factor production, seemingly through the global repressor of toxins—Rot, which functions to regulate S. aureus’ ability to colonize and persist in the host via a complex cascade of signaling. While Rot protein is post-transcriptionally regulated by the highly characterized Agr system, there is little known about its transcriptional regulation. Herein, we explored these dynamics by initially characterizing virulence phenotypes …

Multivalency Of The Mdmx Acidic Domain Slims Use Different Binding Modes To Inhibit Mdmx And P53, Malissa Fenton

USF Tampa Graduate Theses and Dissertations

Regulation of protein binding through autoinhibition commonly occurs via interactions involving intrinsically disordered regions (IDRs). These intramolecular interactions can directly or allosterically inhibit intermolecular protein or DNA binding, regulate enzymatic activity, and control the assembly of large macromolecular complexes. Autoinhibitory interactions mediated by protein disorder are inherently transient, making their identification and characterization challenging. In this work, we explore the structural and functional diversity of disorder-mediated autoinhibition for a variety of biological mechanisms, with a focus on the role of multivalency and effective concentration. We also discuss the evolution of disordered motifs that participate in autoinhibition using examples where sequence …

Effects Of Diminazene Aceturate On Drosophila Melanogaster: A Lipidomic Analysis, Gabriela Suarez

USF Tampa Graduate Theses and Dissertations

Pesticides are agents designed to eradicate living organisms to preserve agricultural needs.¹ Today the most commonly used pesticides are termed “modern pesticides”, they are characterized by lower lipophilicity and limited stability, making them less time persistent in the environment. Among these modern pesticides are organophosphorus, urea, phenoxy alkanoic, triazine, chloroacetanilide, and glyphosate-based pesticides.² The issue faced with most of these pesticides is that they affect more than just the targeted pest and pose a danger to not only humans, but also entire ecosystems.^1,3,4 While there are many different types of pesticides, insecticides show the most variance and …

Preliminary Investigation Of Differences In Host Mitochondria Membrane Potential During Toxoplasma Gondii Infection, Bryan L. Ortega

USF Tampa Graduate Theses and Dissertations

Toxoplasma gondii is an obligate intracellular protozoan with a broad host range of hosts, including various warm-blooded mammals, including humans. While infections can often be asymptomatic in immunocompetent individuals, they can pose significant risks to those who are immunocompromised, as well as pregnant women. Toxoplasmosis represents a significant burden on public health in the United States, with over 800,000 annual infections reported, often leading to severe complications such as symptomatic eye disease and congenital infections. Recent attention has developed regarding its potential association with human neuropathies such as Alzheimer's disease, dementia, and mood disorders. This project investigated differences in host …

Metatranscriptomic Insights Into The Interaction Between Microcystis Blooms And Hydrogen Peroxide, Taylor L. Hancock

USF Tampa Graduate Theses and Dissertations

For this dissertation I studied the interactions of hydrogen peroxide and cyanobacterial harmful algal blooms (cHABs) dominated by Microcystis in the Caloosahatchee River, FL. Specifically, I examined how taxonomic and functional succession relates to both natural hydrogen peroxide dynamics and hydrogen peroxide added to the environment as a cHAB treatment. Chapter 2 investigated how taxonomic succession and gene expression patterns relate to blooms and associated elevated hydrogen peroxide concentrations. The results showed that gene expressions related to cyanobacterial growth were positively correlated with hydrogen peroxide. The genes identified included enzymes capable of hydrogen peroxide generation which were expressed by blooming …

Androgen Drives Melanoma Invasiveness And Metastatic Spread By Inducing Tumorigenic Fucosylation, Qian Liu

USF Tampa Graduate Theses and Dissertations

Melanoma incidence and mortality rates are historically higher for men than women, with an estimated ~47% more new cases and twice the lethality in men in the US in 2023. Consistent with these discrepancies, emerging studies have highlighted the tumorigenic role of the male sex hormone androgen and its receptor (AR) in promoting melanoma aggressiveness. However, underlying cellular and molecular mechanisms and their precise pathological contributions are not well-defined. We recently discovered a sex-associated disparity in melanoma fucosylation, the post-translational modification of proteins with the dietary sugar L-fucose. Fucosylation, the conjugation of fucose moieties onto different glycan linkages on target …

Why Should Early-Career Scientists Publish In Society Journals, Stephen K. Dolan, Lori D. Banks, Wenqi Yu

Molecular Biosciences Faculty Publications

In this editorial, written by early-career scientists, we advocate for the invaluable role of society journals in our scientific community. By choosing to support these journals as authors, peer reviewers, and as editors, we can reinforce our academic growth and benefit from their re-investment back into the scientific ecosystem. Considering the numerous clear merits of this system for future generations of microbiologists and more broadly, society, we argue that early-career researchers should publish our high-quality research in society journals to shape the future of science and scientific publishing landscape.