Molecular Biology Commons^™

Investigating The Role Of The Three N-Terminal Hamp Domains Of The Aer2 Chemoreceptor From Pseudomonas Aeruginosa, Selina Anaya

Loma Linda University Electronic Theses, Dissertations & Projects

Pseudomonas aeruginosa is a ubiquitous environmental bacterium and opportunistic human pathogen. It readily adapts to changing environmental conditions with the aid of 26 chemoreceptors that signal to four distinct chemosensory systems. The Aer2 chemoreceptor from P. aeruginosa is an O2 sensor implicated in stress responses, virulence and fine-tuning the chemotaxis (Che) system. Aer2 is the sole chemoreceptor of the Che2 chemosensory system, which forms complexes at the cell pole during stationary phase. Aer2 is soluble, yet membrane-associated and displays an unusual arrangement with its PAS sensing domain sandwiched between three N-terminal and two C-terminal HAMP domains. HAMP domains are widespread …

Improving The Ribozyme Toolbox: From Structure-Function Insights To Synthetic Biology Applications, Jessica Michelle Roberts

Boise State University Theses and Dissertations

Self-cleaving ribozymes are a naturally occurring class of catalytically active RNA molecules which cleave their own phosphate backbone. In nature, self-cleaving ribozymes are best known for their role in processing concatamers of viral genomes into monomers during viral replication in some RNA viruses, but to a lesser degree have also been implicated in mRNA regulation and processing in bacteria and eukaryotes. In addition to their biological relevance, these RNA enzymes have been harnessed as important biomolecular tools with a variety of applications in fields such as bioengineering. Self-cleaving ribozymes are relatively small and easy to generate in the lab using …

Determining The Full-Length Structure Of Collagenase H Using Small-Angle X-Ray Scattering, Josie Carson

Chemistry & Biochemistry Undergraduate Honors Theses

Known to cause gas gangrene, Hathewaya histolytica secretes two sister collagenases, collagenase G (Col G) and collagenase H (Col H), to degrade the triple helical structure of collagen to further infection in a host. Individual domains of Col H have been crystalized in previous studies, but methods in x-ray crystallization of full-length Col H have been unsuccessful. Using Small Angle X-Ray Scattering (SAXS) data, atomistic modeling was used to generate multiple conformations of Col H while accounting for flexibility between domains. Full-length Col H was found to adopt a two-state conformational model exhibiting a majority compact and a minority elongated …

The Effects Of Stress On The Mammalian Nucleolus And Ribosome Synthesis, Russell T. Sapio

Graduate School of Biomedical Sciences Theses and Dissertations

Ribosomes are responsible for translating every protein in the cell and are essential in all domains of life. Ribosome biosynthesis (RB) takes place in the nucleolus and is an intricate hierarchical process involving over 200 factors, including ribosomal proteins, ribosomal RNA (rRNA), and trans-acting ribosome biogenesis factors (RBFs). Inhibiting RB can disrupt nucleolar integrity, causing ribosomal- and nucleolar-factors to delocalize. This can stabilize the transcription factor p53, which is normally degraded rapidly, ultimately causing cell cycle arrest or apoptosis, through a mechanism termed the nucleolar stress response (NSR). This thesis explores the effects of inhibiting RB post rRNA transcription and …

Complex Regulatory Pathways Connect Vfm Quorum-Sensing And Cyclic-Di-Gmp Signaling To Bacterial Virulence In The Phytopathogen Dickeya Dadantii 3937, Biswarup Banerjee

Theses and Dissertations

The bacterial second messenger Bis-(3’-5’)-cyclic dimeric guanosine monophosphate (c-di-GMP) regulates multiple cellular behaviors in most bacteria. Bacterial c-di-GMP signaling involves enzymes that synthesize and degrade c-di-GMP, c-di-GMP binding effectors, and targets that are acted upon by the effectors. So far, the c-di-GMP signaling pathways have been understudied. In this work, we explore the c-di-GMP signaling network further in the phytopathogen Dickeya dadantii 3937. In Chapter 2, we identified VfmE as a c-di-GMP binding transcriptional activator that represses pectate lyase production under a high c-di-GMP condition. VfmE was found to bind c-di-GMP in vitro via the RxxxR motif, similar to PilZ …

Identifying A Glucocorticoid-Activated Gpcr That Rapidly And Non-Genomically Increases Camp Levels In Mammalian Cells, Francisco Nunez

Pharmaceutical Sciences (PhD) Dissertations

Glucocorticoids (GCs) are steroid hormones that regulate diverse physiological processes. Synthetic versions of GCs are commonly used to treat inflammatory diseases such as asthma by modulating gene expression to suppressing several inflammatory activities. However, it is estimated that 5-10% of asthmatics are unresponsive to GCs, which may be explained by receptor desensitization and/or the presence of a neutrophilic endotype. One understudied phenomenon of GCs is their ability to induce rapid, non-genomic actions. For example, GCs can acutely modulate calcium concentrations levels, induce smooth muscle relaxation and modulate nitric oxide synthase activity, within minutes and sometimes seconds, which is too rapid …

The Role Of The Hypoxia-Inducible Factor 2 In Pancreatic Cancer: Mechanisms Of Tumor Immunosuppression And Intestinal Radioprotection, Carolina Garcia Garcia

Dissertations & Theses (Open Access)

Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease with dismal prognosis. The only curative option for patients is surgery, but over 80% of patients are not surgical candidates. Unfortunately, PDAC is resistant to the three remaining options. PDAC is characterized by a profoundly hypoxic and immunosuppressive stroma, which contributes to its therapeutic recalcitrance. Alpha-smooth muscle actin+ (αSMA+) cancer-associated fibroblasts (CAFs) are the most abundant stromal component, as well as mediators of stromal deposition. The hypoxia-inducible factors (HIF1 and HIF2) coordinate responses to hypoxia, yet, despite their known association to poor patient outcomes, their functions within the PDAC tumor microenvironment (TME) …

Parallel Networks That Govern The Transcriptional Response To Stress, Serene Anne Durham

Legacy Theses & Dissertations (2009 - 2024)

The transcription factor, p53, plays a pivotal role in the oversight of many stimulus-dependent pathways. Its ability to respond to a wide variety of cellular stress stimuli by activating a broad range of target genes has led it to be characterized as a stress-dependent transcription factor. Our research focuses on deconvoluting the varied transcriptional response to distinct stress signals in an attempt to define the regulatory strategies leading to gene activation after cell stress. We have found that distinct stress response networks, some of which are p53-independent, are converging at activation of a common set of target genes. Our data …

N6-Methyladenosine Rna Modifications In Myogenesis / Narrative Competence And Cognitive Mapping As A Culturally Sustaining Pedagogy In The Education Of Emergent Bilinguals, Marina Danielle Infantado

Legacy Theses & Dissertations (2009 - 2024)

Myogenesis involves skeletal muscle stem cells (MuSCs) that produce and regenerate skeletal muscle during regular growth and repair. However, when this system fails to function normally, it can lead to musculoskeletal diseases like Duchenne Muscular Dystrophy (DMD). Therefore, it is important to study the molecular mechanisms behind this developmental process in order to seek therapies and solutions for these types of diseases. Our interest lies in the field of epitranscriptomics, which focuses on post-transcriptional ribonucleic acid (RNA) modifications, particularly N6-methyladenosine (m6A), which involves the addition of a methyl group to the adenosine nucleotide, a process that is mediated by the …

Modeling Electrostatics In Molecular Biology And Its Relevance With Molecular Mechanisms Of Diseases, Mahesh Koirala

All Dissertations

Electrostatics plays an essential role in molecular biology. Modeling electrostatics in molecular biology is complicated due to the water phase, mobile ions, and irregularly shaped inhomogeneous biological macromolecules. This dissertation presents the popular DelPhi package that solves PBE and delivers the electrostatic potential distribution of biomolecules. We used the newly developed DelPhiForce steered Molecular Dynamics (DFMD) approach to model the binding of barstar to barnase and demonstrated that the first-principles method could also model the binding. This dissertation also reflects the use of existing computational approaches to model the effects of Single Amino Acid Variations (SAVs) to reveal molecular mechanisms …

Characterization Of The Wee1 Homologues And The Investigation Of Factors Promoting Cellular Enlargement In Cryptococcus Neoformans, Rodney J. Colón Reyes

All Dissertations

Cryptococcus neoformans is an opportunistic fungal pathogen, infecting mainly immunocompromised individuals. As the main cause of cryptococcosis, it is responsible for over 180,000 deaths every year. As an environmental yeast, it has unique adaptations that allow it to proliferate in the human host. Among these adaptations its capacity to transition to an extreme phenotype known as Titan cells is of special interest to researchers. With sizes above 10 um and able to reach 70 um or more in cell size. This size is accompanied with a large vacuole, larger polysaccharide capsule, and an increased resistance to fluconazole (FLC). FLC is …

Investigating The Biochemical Properties Of A Novel Mutation, A194v, In Human Rad51, Briana Vollbeer

All Theses

DNA double-strand breaks (DSB) are one of the most serious DNA lesions because improper repair of a DSB can lead to loss of heterozygosity, aneuploidy, and cancer. One of the primary pathways to repair DSBs is homologous recombination (HR). HR resects the DNA around the DSB and then uses homologous DNA as a template to restore the broken sequence. RAD51 has a vital function in this pathway by forming a nucleoprotein filament on a resected end of the DSB. The nucleoprotein filament searches for homology within the homologous DNA. Once homology is located, strand invasion followed by strand exchange occurs. …

Perturbation Modeling For Molecular Design Of Protein Tyrosine Kinase Inhibitors Using Unsupervised Machine Learning, Keerthi Krishnan

Computational and Data Sciences (MS) Theses

The field of computational drug discovery and development has grown, with the aid of new computational tools for novel molecule discovery. In specific, generative deep learning models have excelled as tools to aid in navigating the large space of known molecules and in the creation of new molecules. These models are fed various representations of molecules as inputs and learn to perform a variety of things, such as the optimization of these molecules towards a targeted property. Ultimately, these generative learning models allow us to build bridges between chemical and continuous spaces to understand the compromise between invoking small incremental …

Grk3 Connects Angiogenesis And Neuroendocrine Differentiation In Prostate Cancer By Activating Hdac2 That Epigenetically Represses Tsp1 And Rest, Samira Naderinezhad

Dissertations & Theses (Open Access)

Prostate cancer (PCa) is the second most frequent cancer and the second leading cause of mortality in men in the United States. Neuroendocrine prostate cancer (NEPC) is the aggressive subset of castration-resistant prostate cancer (CRPC), found in ~20% lethal CRPC. The mechanisms underlying the progression of PCa to NEPC are still largely unclear, and new drug targets are desperately needed. NEPC is highly vascularized (angiogenic) and characterized by high expression of neuroendocrine markers. However, direct molecular links connecting angiogenesis and neuroendocrine differentiation are elusive.

Since epigenetic regulation has been implicated in NEPC progression, we examined expression patterns of 147 epigenetic …

A Novel Transcription Factor Cder Regulates The Type Iii Secretion System In A C-Di-Gmp Dependent Manner In Dickeya Dadantii, Alaleh Ghasemimianaei

Theses and Dissertations

The enterobacterium, Dickeya dadantii, is an opportunistic bacterial pathogen that causes disease in many plants. C-di-GMP is a ubiquitous bacterial second messenger, regulating multiple cellular behaviors through several c-di- GMP-associated components. Here, we identified a novel transcriptional regulator named CdeR that regulates T3SS in a c-di-GMP-dependent manner. GcpD is a diguanylate cyclase responsible for the synthesis of c-di-GMP. Compared to a gcpD mutant, the gcpD and cdeR double mutant exhibited a reduced T3SS expression. In addition, we found that, under the gcpD mutant background, CdeR regulates T3SS by manipulating intracellular c-di-GMP levels, involving an additional diguanylate cyclase GcpL upregulated by …

Isolation Of Rat Adipose Tissue Mesenchymal Stem Cells For Differentiation Into Insulin-Producing Cells, Dina H. Kassem, Sarah A. Habib, Omar I. Badr, Mohamed M. Kamal

Pharmacy

Mesenchymal stem cells (MSCs)-especially those isolated from adipose tissue (Ad-MSCs)-have gained special attention as a renewable, abundant source of stem cells that does not pose any ethical concerns. However, current methods to isolate Ad-MSCs are not standardized and employ complicated protocols that require special equipment. We isolated Ad-MSCs from the epididymal fat of Sprague-Dawley rats using a simple, reproducible method. The isolated Ad-MSCs usually appear within 3 days post isolation, as adherent cells display fibroblastic morphology. Those cells reach 80% confluency within 1 week of isolation. Afterward, at passage 3-5 (P3-5), a full characterization was carried out for the isolated …

A Computational Model Of The Line-1 Retrotransposon Life Cycle And Visualization Of Metabolic Networks In 3-Dimensions., Michael D. Martin

Electronic Theses and Dissertations

Computational modeling of metabolic reactions and cellular systems is evolving as a tool for quantitative prediction of metabolic parameters and reaction pathway analysis. In this work, the basics of computational cell biology are presented as well as a summary of physical processes within the cell, and the algorithmic methods used to find time dependent solutions. Protein-protein and enzyme-substrate interactions are mathematically represented via mass action kinetics to construct sets of linear differential equations that describe reaction rates and formation of protein complexes. Using mass action methods, examples of reaction networks and their solutions are presented within the Virtual Cell simulation …

Heat Stress Response And Excystation In Entamoeba Histolytica, Irem Bastuzel

All Dissertations

Entamoeba histolytica is a water- and food-borne intestinal protozoan parasite that causes amoebiasis and liver abscess and is responsible for symptomatic disease in approximately 100 million people each year leading to ~ 100,000 deaths. The most common disease transmission follows the oral-fecal route, but it can also be transmitted by mechanical vectors such as animals carrying the amoeba from contaminated sources to water systems. In rare cases, disease transmission has been recorded in some patients in which men-to-men sexual practices were preferred.

The life cycle of E. histolytica starts through ingestion of infectious cysts, which are non-dividing, quadri-nucleated structures surrounded …

Determination Of The Functional Role Of Rab-Ggt In Physcomitrium Patens., Hyun Jin Jung

Electronic Theses and Dissertations

Protein prenylation, a common lipid post-translational modification, is required for growth and development in eukaryotes. Rab geranylgeranylation involves the addition of one or two 20-carbon geranylgeranyl moieties to Rab-GTPase target proteins, which regulate intracellular vesicle trafficking. The reaction is carried out by heterodimeric Rab geranylgeranyltransferase (Rab-GGT), which is composed of two associated α- and β-subunits, with the assistance of an additional protein called Rab escort protein (REP). Loss of function of the Rab-GGT α subunit RGTA1 has not been reported in any plant. While knockout of either of the two β subunits RGTB1 or RGTB2 results in …

Applications Of Nuclear Magnetic Resonance Spectroscopy: From Drug Discovery To Protein Structure And Dynamics., Mark Vincent C. Dela Cerna

Electronic Theses and Dissertations

The versatility of nuclear magnetic resonance (NMR) spectroscopy is apparent when presented with diverse applications to which it can contribute. Here, NMR is used i) as a screening/ validation tool for a drug discovery program targeting the Phosphatase of Regenerating Liver 3 (PRL3), ii) to characterize the conformational heterogeneity of p53 regulator, Murine Double Minute X (MDMX), and iii) to characterize the solution dynamics of guanosine monophosphate kinase (GMPK). Mounting evidence suggesting roles for PRL3 in oncogenesis and metastasis has catapulted it into prominence as a cancer drug target. Yet, despite significant efforts, there are no PRL3 small molecule inhibitors …

Gliding Motility, Protein Secretion, And Virulence Of Fish Pathogen Flavobacterium Columnare., Nicole C. Thunes

Theses and Dissertations

Flavobacterium columnare is an opportunistic fish pathogen that causes columnaris disease in freshwater fish worldwide. Columnaris disease is of particular concern in aquaculture settings where high population density leads to stress and greater infection frequency. High mortality rates and inadequate methods of control exacerbate the problem, creating an urgent need to better understand the mechanisms underlying F. columnare virulence. F. columnare has a type IX secretion system (T9SS), as do many other members of the Bacteroidetes phylum. The F. columnare T9SS secretes cytolysins, proteases, adhesins, and other proteins. The T9SS is also involved in a unique type of movement called …

Improved Molecular Detection Tools For The Invasive Crop Pest Helicoverpa Armigera (Hübner), Mitchell D. Rich

All Theses

Helicoverpa armigera is a major crop pest native to Europe, Asia, Australia, and Africa. H. armigera has recently invaded South America and has caused billions of dollars in agricultural losses. It is difficult to differentiate H. armigera from H. zea, a closely-related species native to North and South America. A few genetic tests have been previously developed to detect H. armigera DNA in pooled samples of moth legs. In this study, an improved qPCR melt curve assay with higher detection sensitivity and a field-based recombinase polymerase amplification (RPA) assay were developed for specific detection of H. armigera DNA …

Bacterial Chondronecrosis With Osteomyelitis In Broilers: Genomics, Phylogenomics, And Methods To Detect Specific Pathogens During Outbreaks., Abdulkarim Abdulaziz A. Shwani

Graduate Theses and Dissertations

Lameness is a major issue in animal welfare and the broiler industry. Bacterial chondronecrosis with osteomyelitis (BCO) is one of the main causes of lameness. Many staphylococcal species, including Staphylococcus agnetis isolate 908, have been isolated from the bones and blood of lame broilers at the University of Arkansas. Staphylococcus agnetis is a coagulase-variable, Gram-positive bacterial species that has been previously associated with subclinical or mild clinical cases of mastitis in dairy cattle. The annotated complete genome of hypervirulent strain 908 was published at NCBI. In this study, it has been compared to nine genomes we assembled for hypervirulent isolates …

Examining The Expression Patterns Of Desulfotalea Psychrophila Dsrab Operon And Pit At Subfreezing Temperatures And Different Concentrations Of Sulfate Salts As A Model For Mars And Icy Worlds Survival And Colonization, Sergio Luis Mosquera Mora

Graduate Theses and Dissertations

Since ancient times, Humanity has been fascinated with the idea of what lies beyond the borders of our planet. Fortunately, the combined efforts of many nations have made it possible to send unmanned spacecraft to orbit planets located close to Earth. These missions have the principal goal to collect data that could help us understand the basic environmental conditions that persist on those planets, or for evidence of past or present life. Equally important, landers and rovers have been successfully deployed to start the in-situ exploration of many planets of the Solar System. Among them, Mars has been extensively studied …

Characterization Of Genetic Pathways Involved In Resistance To A Novel Antifungal Peptide, Kayla L. Haberman

Graduate Theses and Dissertations

Antibiotic resistance is increasing prevalence, particularly in Candida glabrata. This opportunistic pathogen is closely phylogenetically related to Saccharomyces cerevisiae; however, its characterization is limited. C. glabrata is only second to Candida albicans as a fungal pathogen in immunocompromised patients. Commonly resistant to azoles, the most common fungal therapy, it has become costly and challenging to treat. A histatin 5 derived antifungal peptide, KM29, has a high degree of efficacy in Candida species and S. cerevisiae. The objective of this work is to advance our understanding of the mechanism of action of KM29 against C. glabrata. Previous work in the lab …

Validation Of Whole Genome Resequencing For Mapping The Genetics Of Ascites In Broilers And Viral Susceptibility In Layers, Katherine Pepper Lee

Graduate Theses and Dissertations

This dissertation focused on the efficacy and validity of whole genome resequencing (WGR) for fine mapping genetic determinants of particular traits in a given organism. Previously, our research group used WGR to identify haplotype blocks of single nucleotide polymorphisms associated with ascites resistance with some as strong candidates for use in marker-assisted selection (MAS). Chapter 2 discusses the completion of a MAS project through evaluation of ascites incidence as well as production traits of economic value to poultry producers. Thus, the MAS project also covered viability of this methodology in the industry. The MAS significantly reduced ascites incidence in broilers …

Identification Of Genomic, Proteomic, And Metabolomic Signatures Associated With Pulmonary Hypertension Syndrome In Broilers, Duaa Almansaf

Graduate Theses and Dissertations

The present dissertation contains a collection of studies that examine the genomic, proteomic, and metabolomic association to pulmonary hypertension or ascites phenotype in fast-growing broilers. Pulmonary hypertension is a multifactorial metabolic disease influenced by physiological, environmental, and nutritional factors. It is characterized by a number of structural changes including, thrombosis and adverse pulmonary vascular remodeling. Thus, the atrial pressure is increased, and the right ventricle becomes hypertrophied, resulting in heart failure and the death of the bird. Pulmonary hypertension or ascites is a global problem that has negatively impacted the economy. The increased mortality rate of broilers (25%) is estimated …

Investigating The Biorisk Of Genetically Engineered Thermosynechococcus Elongatus Bp1, Cherrelle Leah Barnes

Chemistry & Biochemistry Theses & Dissertations

Cyanobacteria, also known as blue-green algae, are an ancient group of microorganisms that use simple materials, such as sunlight, carbon dioxide and water, to produce energy while providing oxygen to the atmosphere by performing photosynthesis. Synthetic biology approaches have been employed with cyanobacteria as a platform to produce a range of products, such as biofuels, by inserting a series of genes into the cyanobacterial genome that will allow the conversion of metabolic intermediates to such desired products. Although these methods are promising, it is important to understand any potential bio-risk they pose. This research evaluates the potential bio-risk of genetically …

Tetr Family Regulator Farr Variation Controls Antimicrobial Fatty Acid Efflux In Staphylococcus Aureus, Camryn M. Bonn

Electronic Thesis and Dissertation Repository

To colonize human skin and survive within abscesses, Staphylococcus aureus has evolved mechanisms to evade host innate defenses. USA300 has become the predominate community-acquired methicillin-resistant S. aureus (CA-MRSA) clone, which can be in part attributed to detoxification of unsaturated free fatty acids (uFFA) found in sebum and the nares. Our lab has previously identified the TetR family regulator FarR responsible for induction of the resistance-nodulation-division (RND) superfamily efflux pump FarE to promote efflux of toxic uFFA. However, RND family efflux pumps remain poorly characterized in Gram-positive species and the mechanism by which FarR regulates FarE has yet to be determined. …

Leafing Through Literature: Late Embryogenesis Abundant Proteins Coming Of Age – Achievements And Perspectives, Itzell E. Hernandez-Sanchez, Israel Maruri Lopez, Coral Martinez-Martinez, Brett Janis, Juan Francisco Jimenez Bremont, Alejandra A. Covarrubias, Michael A. Menze, Steffen P. Graether, Anja Thalhammer

Faculty Scholarship

To deal with increasingly severe periods of dehydration related to global climate change, it becomes increasingly important to understand the complex strategies many organisms have developed to cope with dehydration and desiccation. While it is undisputed that late embryogenesis abundant (LEA) proteins play a key role in the tolerance of plants and many anhydrobiotic organisms to water limitation, the molecular mechanisms are not well understood. In this review we recap the current knowledge of the physiological roles of LEA proteins and discuss their potential molecular functions. As these are ultimately linked to conformational changes in the presence of binding partners, …