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Articles 1 - 30 of 119
Full-Text Articles in Biochemistry, Biophysics, and Structural Biology
Roles Of Phospholipases And Ribosomal S6 Kinase In Lipid Remodeling And Growth In Arabidopsis Response To Phosphate Deprivation, Yuan Su
Phosphate (Pi) is one of three macronutrients for plants, which is vital for plant growth and development. Understanding the mechanism by which plants respond and adapt to Pi deficiency not only unveils functions of genes and pathways involved, but also provides potential tools to manipulate crops to better stand Pi stress in low Pi-containing lands. One of the significant metabolic changes in plants under Pi starvation is the membrane lipid remodeling that converts Pi-containing lipids such as phospholipids to Pi-free lipids, such as glycolipids. To elucidate the metabolism and regulation of lipid remodeling, this dissertation characterizes the role of two ...
The Characterization Of The Transcription Factor Msab And Its Role In Staphylococcal Virulence, Justin Batte
Staphylococcus aureus is a common human pathogen that is responsible for a wide range of infections, ranging from relative minor skin infections to life-threatening disease such as bacteremia, septicemia, and endocarditis. S. aureus possesses many different virulent factors that aid in its ability to cause this wide array of infections. One major virulence factor includes the production of capsular polysaccharide (CP). The production of CP plays a major role in the virulence response during infection specifically by providing S. aureus an antiphagocytic mechanism that allows the pathogen to evade phagocytosis during an infection. S. aureus has developed complex genetic regulatory ...
A Mechanistic Understanding Of Self-Propagating Amyloid-Β Oligomer Conformations In Alzheimer Disease, Dexter Nathanael Dean
Alzheimer disease (AD) is a fatal neurodegenerative disorder characterized by the widespread deposition of proteinaceous plaques abundant in amyloid-β (Aβ) aggregates. Although the plaques mainly contain high molecular weight, insoluble Aβ fibrils, the low molecular weight soluble aggregates called oligomers have been shown as the primary toxic species responsible for synaptic dysfunction and neuronal loss in AD. The process of aggregation is nucleation-dependent, but also highly stochastic and inhomogeneous resulting in biophysically diverse assemblies. Recent advances in the field indicate a potential correlation between the phenotypic diversity observed in AD subtypes and aggregate polymorphism. Therefore, understanding the molecular mechanisms which ...
Thermodynamics In Large Hairpin Polyamide-Dna Interactions, Yang Song
Human papillomavirus (HPV) is a common sexually transmitted virus responsible for cervical cancers, and its infection is currently incurable. Only a few vaccines against high-risk HPV strains are available. Hairpin polyamides (PAs) in different sizes (8-20 units long) bind DNA in different lengths. They have been shown to have different anti-HPV activities in cell culture.
The interaction between PA and DNA is stabilized by two types of molecular forces: attractive and repulsive forces. Attractive forces include hydrogen bonds, van der Waals contacts and electrostatic forces between PA and DNA. Repulsive forces include the hydrophobic effect, which forces the PA out ...
Comparison Between The Structure-Function Relationship In The Wild Type Gαi1 Protein And Its Oncogenic Mutant, Jesse Lee Goossens
Many signal transduction pathways are regulated by guanine nucleotide-binding (G?) proteins, which function as molecular switches fluctuating between active and inactive conformations. Proper function depends on three flexible switch regions that are involved in the relatively slow hydrolysis of GTP. Deep sequencing studies have found mutations in the GNAS and GNAI1 genes involved in tumorigenesis, among which include a mutation corresponding to a highly conserved arginine residue in the switch II region. A mutation in GNAI1 encoding an R208Q change in G?i1 has been linked to intestinal cancers. We investigated the molecular basis of oncogenesis of this mutant by ...
A Discrete Loop In Serca N-Domain Plays A Role In Serca Headpiece Dynamics And Function, Olga N. Raguimova
The sarco/endoplasmic reticulum calcium ATPase (SERCA) is the major regulator of Ca2+ levels in the cell. Deficient calcium handling in the heart has been linked to heart failure, a leading cause of death in developed countries. As of today, targeting SERCA to enhance cardiac function has not been successful due to lack of details about SERCA structural dynamics during Ca2+ transport.
In my research, I utilized MD simulations and variety of physical assays to determine the role of Nβ5-β6 loop in regulation of SERCA structural dynamics during Ca2+ transport. Previous MD simulations by our lab predicted that the Nβ5-β6 ...
Elucidating Mechanisms Of Protein Aggregation In Alzheimer’S Disease Using Antibody-Based Strategies., Benjamin A. Colvin
Alzheimer’s Disease (AD) is a devastating neurodegenerative disorder. There are two characteristic histopathological hallmarks in the brain: senile plaques and neurofibrillary tangles, composed of insoluble aggregates of the amyloids Amyloid-β (Aβ) and tau protein, respectively. These diagnostic markers, though distinctive, are not apparent effectors of AD pathology. Evidence has mounted suggesting smaller soluble aggregates (oligomers) of Aβ or tau are the true drivers of disease progression. This dissertation presents several amyloid biophysics projects. Aggregate biophysical parameters such as weight, shape, and conformation were measured using a range of methodologies, including Multiangle Light Scattering, Dynamic Light Scattering, UV-Circular Dichroism, UV-Fluorescence ...
Disorder In Cysteine-Rich Granulin-3 And Its Implication In Alzheimer Disease, Gaurav Ghag
Granulins (GRNs) are a family of small, cysteine-rich proteins that are generated upon proteolytic cleavage of their precursor, progranulin (PGRN) during inflammation. All seven GRNs (1 – 7 or A – G) contain twelve conserved cysteines that form six intramolecular disulfide bonds, rendering this family of proteins unique. GRNs play multiple roles and are involved in a myriad of physiological as well as pathological processes. They are known to a play role in growth and embryonic development, wound healing, and signaling cascades as well as in tumorigenesis. They are also implicated in neurodegenerative diseases like frontotemporal dementia (FTD), Alzheimer disease (AD), and ...
Uncovering The Identity And Metabolism Of Bacterial Coa-Rna, Joseph R. Spangler
Uncovering The Identity And Metabolism Of Bacterial Coa-Rna, Joseph R. Spangler
Coenzyme A is an indispensable molecule in all known life with roles in metabolism, gene regulation, and macromolecule synthesis. As CoA is derived from RNA itself, it’s incorporation into RNA by in vitro methods has proven useful in research probing the origin of life based on the RNA World theory. The discovery in contemporary bacteria of RNA modified with CoA, however, provided an unexpected twist to previously well-characterized bacterial systems. The identity of sequences associated with CoA-RNA has been elusive since their discovery in 2009 based on the difficulties in isolation while maintaining RNA quality. The aim of this ...
Dna-Binding And Cellular Uptake Properties Of Pyrrole-Imidazole Polyamides, Maria J. Scuderi
Pyrrole-imidazole polyamides (PAs) represent a class of synthetic ligands that bind to the minor groove of DNA through hydrogen bonds and can be programmed to recognize predetermined DNA sequences. Potential applications of these compounds include gene expression modulation, antimicrobial activity and cell imaging.
Studies conducted in our lab in collaboration with NanoVir have shown that large PAs exhibit antiviral activity against Human Papillomavirus (HPV), which is the most common sexually transmitted infectious agent in the US and the primary factor for the development of cervical cancer. PAs act against HPV by targeting the viral DNA and promoting its selective elimination ...
Biophysical Studies Of Hairpin Polyamides With Broad-Spectrum Activity Against High-Risk Human Papillomaviruses, Carlos H. Castaneda
Human papillomavirus is a small dsDNA virus that infects mucosal and cutaneous epithelial tissues. Persistent infection with high-risk HPV is the main etiological agent in the development of cervical cancer worldwide. Although prophylactic vaccines against HPV are available, these preventative measures are type-specific and are ineffective against existing infections. Thus, there is a pressing need for antiviral drugs with a broad-spectrum activity against HPV to eradicate existing infections, no matter the subtype.
Our group and collaborators have synthesized an extensive library of novel N-methylpyrrole/N-methylimidazole (Py/Im) hairpin polyamides (PAs) with broad-spectrum activities against three prevalent oncogenic-HPV types ...
Frnk Regulatory Complex Formation With Fak Is Regulated By Erk Mediated Serine 217 Phosphorylation, Taylor J. Zak
Focal adhesion kinase related non-kinase (FRNK) is an endogenous inhibitor of focal adhesion kinase (FAK) that has traditionally been used to inhibit FAK signaling in a variety of experiments and is also an important endogenous regulator of FAK signaling. More recently, FRNK has been shown to be of increasing importance in some pathologic conditions. Despite the increasing importance of FRNK, the molecular mechanism by which it functions remains unclear. In addition, FRNK contains several phosphorylation sites with unknown importance and function. Here I hypothesize that FRNK can inhibit FAK by binding directly to FAK within focal adhesions. Furthermore, I propose ...
Investigating The Functional Role Of Tick Antioxidants In Hematophagy And Vector Competence, Deepak Kumar
Ticks are obligate hematophagous arthropods and harbor several pathogens which transmit various diseases to humans and their domesticated animals. Host blood- digestion in a tick midgut (MG) generates several reactive oxygen species (ROS), which are extremely toxic to essential macromolecules (e.g. DNA, proteins, and lipids) within the cell, resulting in high oxidative stress. Thus, this dissertation focuses on the questions of how tick homeostasis responds to high oxidative stress, and how ticks and their harbored pathogens survive the high surge of oxidative stress during blood digestion. We are specifically interested in the tick-pathogen, Rickettsia parkeri (R. parkeri, Rp), harbored ...
Electrogenerated Chemiluminescence Study Of Semiconductor Nanoparticles Towards Sensitive Detection Of Biomolecules, Yiliyasi Wusimanjiang
The main focus of this dissertation is to unfold the fundamental aspects of electrogenerated chemiluminescence (ECL) generation from semiconductor nanoparticles (also known as quantum dots or QDs) within different ECL systems. The ECL and photo-physical interactions between the CdTe QDs (λemission= ~760 nm) and the CdSe QDs (λemission= ~550 nm), as well as the effects of carbon nanotubes on ECL of QDs were separately investigated. Optimum experimental conditions for peptide bond formation on an electrode surface through EDC (1-ethyl-3-(-3-dimethylaminopropyl) carbodiimide hydrochloride)/NHS (N-Hydroxysulfosuccinimide) coupling were also revealed using cyclic voltammetry technique. Based on the information obtained ...
Analysis Of The Intricacies Of Substrate Recognition Of High Mobility Group Proteins And Aminoacyl-Trna Synthetases Using Non-Cognate Substrates, Douglas Van Iverson Ii
The studies presented in section 1 (Chapters I-IV) focus on the design and development of nucleic acid four-way junctions (4WJs) to target a member of the high mobility group (HMG) proteins, the proinflammatory cytokine high mobility group box 1 protein (HMGB1). In the present study, hybrid PNA-DNA 4WJs based on a model DNA 4WJ were constructed to improve the thermal stability of 4WJs while maintaining strong binding affinity toward HMGB1. An electrophoretic mobility shift assay (EMSA) was used to examine the binding affinity of an isolated DNA binding domain of HMGB1, the HMGB1 b-box (HMGB1b), toward a set of PNA-DNA ...
Characterization Of Glycine Rich Proteins From The Salivary Glands Of The Lone Star Tick Amblyomma Americanum, Rebekah Lynn Bullard
Ticks are blood sucking arthropods that feed on living hosts for up to three weeks. The ticks secrete a multitude of pharmacologically active proteins into the host during feeding which allow the tick to avoid the host immune response, establish a blood pool, and form a firm attachment. The firm attachment is facilitated by the formation of a cement cone which surrounds the tick mouthparts and intertwine between the host skin layers. In this study, gene expression of 44 A. americanum genes was measured throughout the bloodmeal to reveal the differential expression of these genes. Each of the genes tested ...
Mechanistic Variations Of The Bronsted Linear Free Energy Relationships For Nonezymatic Nucleotidyl Transfer Reactions, Zheng Zhang
As the essential enzymes in human bodies, DNA polymerases play a significant role in DNA replication, repair, genetic recombination, and reverse transcription. In 1956, the enzyme of DNA polymerase I, also named as Pol I, was discovered by Arthur Kornberg and colleagues. Subsequently, the Noble Committee had decided that the Noble Prize in Physiology or Medicine for 1959 was to be awarded to Kornberg for his excellent original work that describes the DNA replication process whereby the DNA polymerase copies the nucleotide sequence of a DNA template strand. Because of the complex enzyme structure in the DNA polymerase, it is ...
Heart And Sole: The Functional Role Of Fast-Skeletal Myosin Binding Protein-C In Cardiac And Skeletal Muscle, Brian Leei Lin
The goal of my dissertation was to compare and contrast the function of all three major isoforms of Myosin Binding Protein-C (MyBP-C): slow-skeletal, fast-skeletal, and cardiac (ssMyBP-C, fsMyBP-C, and cMyBP-C, respectively), with a focus on the least characterized isoform, fsMyBP-C. Using a variety of ex vivo, in vitro, and in silico methods, my research demonstrated that the N-terminal region of all MyBP-C isoforms bind to actin and shift tropomyosin, thus activating the thin filament during contraction. Furthermore, each isoform differentially activated the thin filament over isoform-specific ranges of Ca2+: slow-skeletal activates at low Ca2+, fast-skeletal activates at higher Ca2+, and ...
Studies Into The Allosteric Regulation Of Adp-Glucose Pyrophosphorylases, Benjamin Luke Hill
Studies Into The Allosteric Regulation Of Adp-Glucose Pyrophosphorylases, Benjamin Luke Hill
The synthesis of glycogen in bacteria and starch in plants is allosterically controlled by the production of ADP-glucose by ADP-glucose pyrophosphorylase. Using computational studies, site directed mutagenesis, and kinetic characterization, and protein crystallography we found a critical region for transmitting the allosteric signal in the Escherichia coli and A. tumefaciens ADP-glucose pyrophosphorylase. Molecular dynamics simulations and structural comparisons with other ADP-glucose pyrophosphorylases provided information to hypothesize communication pathways that link allosteric and active sites, and this was tested by site-directed mutagenesis and kinetic characterization of the mutant enzymes. In addition, the application of x-ray crystallography enabled the pinpointing of the ...
The Role Of Foxo Transcription Factors In Alcohol-Induced Deficient Fracture Repair, Philip M. Roper
Proper and complete repair of a bone fracture is essential in quality of life maintenance, but poor healing and fracture malunion are still medically and socially relevant problems. Alcohol abuse impairs normal fracture healing, leading to delayed or incomplete union. This dissertation aims to clarify mechanisms behind this alcohol-induced impaired healing, thereby elucidating potential methods of intervention.
Alcohol-induced oxidative stress has been linked to many morbidities associated with alcohol abuse. This dissertation elucidates a potential mechanism through which alcohol inhibits fracture healing by increasing oxidative stress. Using a rodent model, I found that alcohol exposure decreases fracture callus formation and ...
The Role Of Microrna In Cardioprotection: Ischemic Preconditioning And Mesenchymal Stem Cell Paracrine Effects, Kristin Luther
Changes in gene expression and protein levels are an important aspect of cardioprotection in which short non-coding RNA known as miRNA may play a key regulatory role. We investigated the functions of several miRNAs in the context of two cardioprotective stimuli, ischemic preconditioning (IPC) and mesenchymal stem cell (MSC) paracrine effects. We hypothesized that downregulation of a set of miRNAs (miR-148a/b, miR-30b, and let-7a*) augments expression of protective heat shock proteins during IPC, and that MSC exosomes transfer miR-21 to cardiomyocytes, resulting in downregulation of pro-apoptotic genes and reduction of infarct size.
IPC increased the level of Hsp70, Hsp90 ...
Development Of "Inside-Out" Pegylated Crosslinked Hemoglobin Polymers: Novel Hemoglobin-Based Oxygen Carriers (Hboc), Kyle Douglas Webster
The development of an effective blood substitute is urgent due to increasingly common blood shortages, the need to type-match donated blood, and communicable diseases (e.g. HIV) posing risks for blood transfusions around the world. There have been many attempts at creating hemoglobin-based oxygen carriers (HBOC) using a variety of techniques centered around the use of polyethylene glycol (PEG) conjugated to hemoglobin (Hb) tetramers. A novel method, “Inside-Out” PEGylation, has been developed by our lab to produce a polyethylene glycol crosslinked hemoglobin (PEG XL-Hb) polymer. This method utilizes a single PEG backbone that is surrounded by multiple proteins, instead of ...
Investigations Of Filarial Nematode Motility, Response To Drug Treatment, And Pathology, Charles Nutting
More than a billion people live at risk of chronic diseases caused by parasitic filarial nematodes. These diseases: lymphatic filariasis, onchocerciasis, and loaisis cause significant morbidity, degrading the health, quality of life, and economic productivity of those who suffer from them. Though treatable, there is no cure to rid those infected of adult parasites. The parasites can modulate the immune system and live for 10-15 years. Testing of compounds against filarial nematodes is complicated due to a lack of an objective platform on which to analyze in vitro treatments. There is no published, immunocompetent laboratory model for lymphatic filariasis. This ...
The Endosomal Sorting Complex Required For Transport Pathway Mediates Chemokine Receptor Cxcr4 Akt Signaling By Promoting Lysosomal Degradation Of Mtor Antagonist Deptor, Rita Ramkaran Verma
The chemokine receptor CXCR4 is a member of the G protein-coupled receptor (GPCR) family. The cognate ligand for CXCR4 is the C-X-C chemokine known as CXCL12. The CXCL12/CXCR4 signaling axis is essential for a number of developmental processes including organogenesis, vascularization of the GI tract and hematopoiesis. Dysregulated CXCR4 signaling is also implicated in a variety of pathological conditions such as WHIM (Warts, Hypogammaglobunemia, Infections and myelokathexis) syndrome, cardiovascular disease and cancer. Despite its role in several pathologies, the molecular mechanisms mediating CXCR4 signaling are not completely understood. Upon CXCL12 binding to CXCR4, several signaling pathways are activated including ...
Regulation Of Cxcr4 Intracellular Trafficking By Ubiquitin, Justine Elizabeth Kennedy
Regulation Of Cxcr4 Intracellular Trafficking By Ubiquitin, Justine Elizabeth Kennedy
G protein-coupled receptor (GPCR) sorting into the degradative pathway is important for attenuating signaling. Perturbations in this process can manifest in a variety of diseases. Upon agonist activation of the chemokine receptor CXCR4, a GPCR, it is rapidly ubiquitinated, internalized to endosomes and sorted for degradation in lysosomes via the endosomal sorting complex required for transport (ESCRT) pathway. This process culminates in attenuation of CXCR4 signaling. CXCR4 overexpression and increased CXCR4 signaling have been associated with several pathologies including immune deficiency disorders and over 23 cancers. Yet the mechanisms governing the regulation of CXCR4 signaling remain elusive.
CXCR4 is ubiquitinated ...
Study Of Escherichia Coli Adp-Glucose Pyrophosphorylase Catalysis: Investigating Critical Roles Of Conserved Arg32 And Lys42 Residues, Angela Lynn Mahaffey
Carbohydrates have been most notable as energy sources for mammals, bacteria (glycogen) and plants (starch) – and in many other species. As such the biosynthesis of carbohydrates is essential to the sustainability of many forms of life, on earth. Adenosine-‘5-diphosphate glucose pyrophosphate (ADP-Glc pyrophosphorylase; ADP-Glc PPase) is the allosterically controlled “first committed step” in both the biosynthetic pathways of starch (~25% amylose and ~75% amylopectin, in plants and algae) and glycogen (in bacteria), preceding the starch/glycogen synthase reaction. By catalyzing the following reaction, ATP + α –D-Glc-1P ADP-Glc + PPi , ADP-Glc PPase functions as the primary enzyme in the reaction that ...
Structure And Molecular Mechanism Of A Plp/Gaba Dependent Transcription Regulator Gabr, Rui Wu
GabR is a member of the MocR/GabR subfamily of the GntR family of bacterial transcription regulators. It regulates the metabolism of γ-aminobutyric acid (GABA), an important nitrogen and carbon source in many bacteria. The crystal structures reported here show that this protein has evolved from the fusion of a type I aminotransferase and a winged helix-turn-helix (wHTH) DNA binding protein to form a chimeric protein that adopts a dimeric head-to-tail configuration. The pyridoxal 5′-phosphate (PLP)-binding regulatory domain of GabR is therefore an example of a coenzyme playing a role in transcription regulation rather than in enzymatic catalysis ...
Eliminating Acute Myeloid Leukemia Stem Cells By Targeting The Niche Microenviromnent: Co-Inhibition Of Tnf/Il1- Jnk And Nf-Κb, Andrew Volk
Leukemia Stem Cells (LSCs) from Acute Myeloid Leukemia (AML) require the activity of the transcription factor NF-kB to maintain stemness and drive tumor formation. Blocking NF-kB can preferentially eliminate LSCs in vitro with minimal effects on healthy Hematopoietic Stem and Progenitor Cells (HSPCs), making NF-kB a compelling target for anti-leukemia therapies. However, blocking NF-kB in vivo can only extend survival for a short period of time before transplanted mice succumb to the disease. I propose this is due to components of the in vivo niche supporting LSC survival and compensating for the inhibition of NF-kB.
I observed patients with partially ...
The Mir-17-92 Cluster Contributes To Mll Leukemia Development Through The Repression Of The Meis1 Competitor Pknox1, Yousaf Anwar Mian
Mixed lineage leukemias have a relatively poor prognosis and arise as a result of translocations between the MLL gene and one of multiple partner genes. Downstream targets of MLL are aberrantly upregulated and include the developmentally important HOX genes and MEIS1, as well as multiple miRNAs, including the miR-17-92 cluster and miR-196b. Here I utilize custom anti-miRNA oligonucleotides to examine the contribution of specific miRNAs to MLL leukemias both as individual miRNAs and in cooperation with other miRNAs. Combinatorial treatment with antagomirs against miR-17 and miR-19a of the miR-17-92 cluster dramatically reduces colony forming ability of MLL-fusion containing cell lines ...
Characterization And Role Of Msaabcr In Biofilm Development And Virulence In Staphylococcus Aureus, Gyan Sundar Sahukhal
Community-acquired, methicillin-resistant Staphylococcus aureus strains often cause localized infections in immune-compromised hosts, but some strains show enhanced virulence leading to severe infections even among healthy individuals with no predisposing risk factors. The genetic basis for this enhanced virulence has yet to be determined. S. aureus possesses a wide variety of virulence factors, the expression of which is carefully coordinated by a variety of regulators. Several virulence regulators have been well characterized, but others have yet to be thoroughly investigated. Previously, the msa gene as a regulator of several virulence genes, biofilm development, and antibiotic ...