Biochemistry, Biophysics, and Structural Biology Commons^™

Conformational Motions Associated With Ligand Binding In Dihydrofolate Reductase From Bacillus Stearothermophilus, Mayam Tobilola Alapa

Theses, Dissertations and Culminating Projects

A fluorescently-labeled, conformationally-sensitive Bacillus stearothermophilus (Bs) dihydrofolate reductase (DHFR) (C73A/S131C_MDCC DHFR) was developed and used to investigate kinetics and protein conformational motions associated with methotrexate (MTX) binding. This construct bears a covalently attached fluorophore, N-[2-(lmaleimidyl) ethyl]-7-(diethylamino)coumarin-3-carboxamide (MDCC) attached at a distal cysteine, introduced by mutagenesis. The probe is sensitive to the local molecular environment, reporting on changes in the protein structure associated with ligand binding. Intrinsic tryptophan fluorescence of the unlabeled Bs DHFR construct (C73A/S131C DHFR) also showed changes upon MTX association. Stopped-flow analysis of all data can be understood by invoking the presence of two native state DHFR …

A Leishmania Mitogen Activated Protein Kinase As A Potential Anti-Parasitic Drug Target : Purification, Characterization And Inhibitor Interactions, Aysenur Sayakci

Theses, Dissertations and Culminating Projects

The disease, Leishmaniasis, is caused by the protozoal parasite Leishmania, which is transmitted by the bite of an infected Phlebotomine female sandfly. It is a significant health problem in tropical regions of the world and new therapeutic approaches for treating this disease are urgently needed.

Protozoal MAPKs (Mitogen Activated Protein Kinases) play important roles in parasite viability and infectivity and as such, represent viable drug targets. It has been demonstrated that LmxMPKl is an essential MAPK required for the parasite to establish infection and for proliferation of the amastigote stage (the mammalian stage of the parasite) of the parasite. In …

Structural Analysis Of The Drosophila Innexin Shakb: Role Of The N-Terminus In Rectifying Electrical Synapses, William Marks

Biology Theses

Gap junction channels mediate direct intercellular communication in all multicellular animals. They are comprised of the connexin family of proteins in vertebrates and the innexin family in prechordates. Connexins and innexins share many functional and structural similarities as orthologous proteins. Both types are capable of forming electrical synapses. Rectifying junctions are specialized electrical synapses found in neural systems that control escape responses. It has been shown that heterotypic gap junction channels mediate asymmetric properties of rectifying junctions. Shaking B N+16 and Shaking B lethal are variants of the ShakB locus in Drosophila and the organization of these innexins into heterotypic …

Does Vibrational Loading Modulate The Effects Of Radiotherapy On Growing Bone?, Samantha Hay

Renée Crown University Honors Thesis Projects - All

Radiotherapy is an important part of cancer therapy, used in addition to surgery for treatment of patients with soft tissue sarcomas, and alternatively for treatment of patients with Ewing sarcoma of bone. Treating pediatric extremity tumors with radiotherapy has been shown to have harmful effects on the epiphyseal plate, resulting in permanent limb shortening and deformity when bone growth centers are exposed to radiation. Mechanical signals, specifically low-magnitude high-frequency vibrations (LMHFV), have been shown to be non-invasive and non-pharmacological growth factors in bone that have the potential to serve as a safe treatment for a number of clinical conditions. Thus, …

Expression And Purification Of Recombinant Saposin B For Coenzyme Q10 Purification, Vivian Yaci Yu

Renée Crown University Honors Thesis Projects - All

Coenzyme Q10 (CoQ10) plays a critical role in energy production in humans. Low levels of CoQ10 have been linked to diseases such as Parkinson's and Huntingtons's disease. CoQ10 levels decrease as we age, and use of statin drugs also lowers CoQ10 levels. Oral supplementation however increases CoQ10 levels. However, the lack of industrial sources of CoQ10 and the difficulty in CoQ10 purification has resulted the need to address these problems. Sporidiobolus johnsonii (S. johnsonii) has been reported as a natural producer of CoQ10. This work is aim to increase the production of CoQ10 in S. johnsonii through genetic …

Gold (Iii) Macrocycles Are Dna Intercalators That Inhibit Topoisomerase I And Ii, Alexander Fagenson

HIM 1990-2015

Human Topoisomerase IB (TOP1) and Topoisomerase II? (TOP2?) are essential nuclear enzymes that control DNA topology during DNA replication, gene transcription and cell division. These enzymes carry out their catalytic function by making transient single-strand (type I) or double-strand (type II) breaks in the DNA. In vivo, these complexes are short-lived but can be exploited by anti-cancer drugs to mechanistically kill cancer cells. Two general classes of compounds can kill cancer cells through a topo-targeted mechanism. Interfacial Poisons (IFPs) act at the enzyme-DNA interface to inhibit the religation reaction, resulting in the accumulation of DNA double-stand breaks (DSBs) in the …

Design, Construction, And Characterization Of The Ysgr Minimal Codon Fab Library For Chaperone-Assisted Rna Crystallography, Sean Holmes

HIM 1990-2015

Of the entire human genome, 90% of all genetic information is transcribed but only a fraction of that subsequent RNA is translated into proteins. RNAs which are not translated into proteins are deemed non-coding RNAs. Little is known about this large category of noncoding RNAs, although they perform a variety of functions within the cell. RNA crystallography is used to study RNA tertiary structure, which gives insight to the function of these non-coding RNAs. However, complications associated with RNA crystallography arise due to RNA's lack of surface functional group diversity, flexible tertiary structure, and conformational heterogeneity. A novel technique, Chaperone-assisted …

Determination Of The Hydrogen Peroxide Concentration In Rotenone Induced Dopaminergic Cells Using Cyclic Voltammetry And Amplex Red, Kishan Patel

HIM 1990-2015

Parkinson's disease (PD) is a neurodegenerative condition that affects millions of people worldwide. The exact etiology of PD is unknown. However, it is well established that environmental factors contribute to the onset of PD. In particular, chemicals such as the insecticide Rotenone have been shown to increase the death of dopaminergic (DA) neurons by increasing levels of reactive oxygen species (ROS). ROS such as hydrogen peroxide (H2O2) have been shown to be elevated above basal levels in PD patients. Currently, to measure H2O2 concentrations, a commercially available (Amplex® Red) fluorescent assay is used. However, the assay has limitations: it is …

Identification Of Plasmodium Falciparum Protein Kinase Substrates And Interacting Proteins, Jessica Yap

HIM 1990-2015

Characterization of PfPKA and PfPK5 substrates, as well as the proteins they interact with, will help us to develop innovative therapies targeting binding sites.; Malaria is a devastating disease that results in almost one million deaths annually. Most of the victims are children under the age of five in Sub-Saharan Africa. Malaria parasite strains throughout developing countries are continually building resistance to available drugs. Current therapies such as mefloquine, chloroquine, as well as artemisinin are becoming less effective, and this underscores the urgency for therapeutics directed against novel drug targets. In order to identify new drug targets, the molecular biology …

1. Improving The Yield Of Biodiesel From Microalgae And Other Lipids. 2. Studies Of The Wax Ester Biosynthetic Pathway And Potential Biotechnological Application, Bradley D. Wahlen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The production of biofuels and oleochemicals from renewable sources offers an opportunity to reduce our dependence on fossil fuels. The work contained in this dissertation has focused on developing and improving methods for the production of biodiesel from non-traditional feedstocks and understanding biosynthetic pathways that result in the production of oleochemicals and fuels.

Pure vegetable oil can account for 70-80% of the total cost of biodiesel production. Many low-cost oils contain high amounts of free fatty acids, which are unsuitable for base-catalyzed transesterification. Herein an approach is described that efficiently accomplishes the simultaneous esterification and transesterification of both free fatty …

Structure Of The Catalytic Chain Of Methanococcus Jannaschii Aspartate Transcarbamoylase In A Hexagonal Crystal Form: Insights Into The Path Of Carbamoyl Phosphate To The Active Site Of The Enzyme, Jacqueline Vitali, Aditya K. Singh, Alexei S. Soaresb, Michael J. Colaneri

Physics Faculty Publications

Crystals of the catalytic chain of Methanococcus jannaschii aspartate transcarbamoylase (ATCase) grew in the presence of the regulatory chain in the hexagonal space group P6₃22, with one monomer per asymmetric unit. This is the first time that crystals with only one monomer in the asymmetric unit have been obtained; all known structures of the catalytic subunit contain several crystallographically independent monomers. The symmetry-related chains form the staggered dimer of trimers observed in the other known structures of the catalytic subunit. The central channel of the catalytic subunit contains a sulfate ion and a K⁺ ion as …

Synthesis And Structural Studies Of Calcium And Magnesium Diphosphonate Compounds, Seungmo Suh

Renée Crown University Honors Thesis Projects - All

The purpose of this project is to study synthetic methodologies leading to the designing of various calcium and magnesium based diphosphonates with possible applications as bone scaffolding materials. In tissue engineering scaffolds are frequently employed to enhance the growth of new cells, providing the motivation to study alkaline earth metal based diphosphonates as a possible source for scaffold for bone growth.

While the transition metal phosphonates based frameworks are well studied, alkaline earth metal based phosphonates and diphosphonates remain at its infancy. The challenge to the chemistry of the alkaline earth metal phosphonates and diphosphonates based frameworks includes poor solubility …

Studies On The Small Ubiquitin-Like Modifier (Sumo) E2 Conjugases Of The Sumoylation System In Chlamydomonas Reinhardtii And Their Role In Stress Physiology, Amy R. Knobbe

Department of Biochemistry: Dissertations, Theses, and Student Research

The eukaryotic protein post-translational modification by SUMOylation is involved in a diverse array of cellular processes, including various stress responses. A fully functional SUMOylation system is present in the unicellular green alga Chlamydomonas reinhardtii, and SUMOylation of multiple high molecular weight proteins is induced in response to abiotic stress in this organism. We report here the characterization of a SUMO E2 conjugase deletion mutant in C. reinhardtii, mut5. SUMO E2 conjugase enzymes are responsible for the conjugation of the protein SUMO to a lysine residue within a target protein. C. reinhardtii mutants in which the SUMO E2 …

Developing A High Throughput Protocol For Using Soil Molecular Biology As Trace Evidence, Sabreena A. Larson

Department of Biochemistry: Dissertations, Theses, and Student Research

The use of soil as trace evidence has changed significantly with the addition of new techniques. These techniques include using the biochemical molecules from soil microbial communities to make a fingerprint of the specific soil. This research examines the changes to the microbial community profile that take place during storage of a soil sample. To observe such changes both the DNA and fatty acid profiles will be examined.

The DNA profiles were made with capillary electrophoresis-single stranded conformation polymorphism (CE-SSCP). After statistical analysis using Bray-Curtis distances and ANOSIM (analysis of similarity) it was shown that storage of soil does not …

Development Of An Assay To Screen For Novel Proteins From Bacillus Thuringiensis With Antibacterial Activity, Auriole T. Tamegnon

Theses and Dissertations - UTB/UTPA

Bacillus thuringiensis (Bt) produces the non specific Cyt protein and the specific Cry protein. Past research has shown these proteins are toxic to insects, red blood cells, cancer cells, and some bacteria. While many antibacterial substances are known to exist, efforts to find new ones still continue. In this project we used Bt 6-2-56 (containing a novel filament associated parasporal body which appears non-toxic to insects and protozoan) and Bt 4Q13 (which has been shown to have activity against E. coli and S. aureus) to develop a simple, easy, scalable assay in a 96 well Microtitre plate to look for …

Activation Of The Carbon Concentrating Mechanism By Co2 Deprivation Coincides With Massive Transcriptional Restructuring In Chlamydomonas Reinhardtii, Andrew J. Brueggeman, Dayananda S. Gangadharaiah, Matyas F. Cserhati, David Casero, Donald P. Weeks, Istvan Ladunga

Department of Biochemistry: Faculty Publications

A CO₂-concentrating mechanism (CCM) is essential for the growth of most eukaryotic algae under ambient (392 ppm) and very low (ppm) CO₂ concentrations. In this study, we used replicated deep mRNA sequencing and regulatory network reconstruction to capture a remarkable scope of changes in gene expression that occurs when Chlamydomonas reinhardtii cells are shifted from high to very low levels of CO₂ (£100 ppm). CCM induction 30 to 180 min post-CO₂ deprivation coincides with statistically significant changes in the expression of an astonishing 38% (5884) of the 15,501 nonoverlapping C. reinhardtii genes. Of these genes, …

Development And Evaluation Of A Mouse Neocortical Cells Neurodevelopment Assay To Assess The Effects Of Pyrethroids, Stephanie I. Savino

Pell Scholars and Senior Theses

Pyrethroid insecticides have been used for more than 40 years and account for 25% of the global insecticide market with household, agricultural and public health applications. With increasing use of pyrethroids over recent years, human exposure to these chemicals is likely. The acute toxicity of pyrethroids to mammalian adults has been documented as moderately toxic by the U.S. Environmental Protection Agency. However, little evidence is available regarding the potential toxicological effects of pyrethroids on mammalian neurodevelopment. In this study, a neurodevelopment assay was developed for future investigation of potential pyrethroid effects on the neuronal development of Mus musculus neocortical cells.

Syntaxin 6- And Microtubule- Mediated Intracellular Trafficking Contributes To Golgi And Nuclear Translocation Of Egfr, Yi Du

Dissertations and Theses (Open Access)

Receptor-mediated endocytosis is well known for its degradation and recycling trafficking. Recent evidence shows that these cell surface receptors translocate from cell surface to different cellular compartments, including the Golgi, mitochondria, endoplasmic reticulum (ER), and the nucleus to regulate physiological and pathological functions. Although some trafficking mechanisms have been resolved, the mechanism of intracellular trafficking from cell surface to the Golgi is not yet completed understood. Here we report a mechanism of Golgi translocation of EGFR in which EGF-induced EGFR travels to the Golgi via microtubule (MT)-dependent movement by interacting with dynein and fuses with the Golgi through syntaxin 6 …

Structural And Mechanistic Investigations Of Phosphothreonine Lyase Class Of Enzymes, Alok Gopalkrishna Shenoy

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Phosphorylation and dephosphorylation are a highly pervasive mechanism in biology that is used by the cell to modulate enzymes and proteins. The presence of a phosphate group can activate or deactivate an enzyme. The phosphate group is linked to a protein by a phosphoester bond that is known to be highly stable in cytoplasmic pH range. Thus the breaking and formation of these bonds need to be effected by enzymes.

Recent discovery of the activity carried out by certain virulence related proteins (OspF released by Shigella and SpvC released by Salmonella) have resulted in a necessity to create a new …

Biochemical Characterization Of Sac9, A Putative Phosphoinositide Phosphatase In Arabidopsis Thaliana, And Its Role In Cellular Abnormalities, Almut H. Vollmer

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Since the early colonization of land by fungi and plants some 700 million years ago, plants have been continuously faced with changes in their environment. Unlike animals, plants are not free to move about, and can therefore not evade many stress factors. How plants sense and respond to their environment has been of interest not only to scientific research but also in more practical applications such as agriculture.

Signals (such as light or salinity) from the outside of plant cells trigger a flow of information to the inside of the cell. The final target for most of the information is …

Determining The Genotype-Phenotype Connection In Synthetic Inducible Gene Expression Systems, Rhys M. Adams

Dissertations and Theses (Open Access)

Introduction Gene expression is an important process whereby the genotype controls an individual cell’s phenotype. However, even genetically identical cells display a variety of phenotypes, which may be attributed to differences in their environment. Yet, even after controlling for these two factors, individual phenotypes still diverge due to noisy gene expression. Synthetic gene expression systems allow investigators to isolate, control, and measure the effects of noise on cell phenotypes. I used mathematical and computational methods to design, study, and predict the behavior of synthetic gene expression systems in S. cerevisiae, which were affected by noise.

Methods I created probabilistic …

Increased Geranylgeranylated K-Ras Contributes To Antineoplastic Effects Of Farnesyltransferase Inhibitors., Mandy A. Hall

Dissertations and Theses (Open Access)

The Ras family of small GTPases (N-, H-, and K-Ras) is a group of important signaling mediators. Ras is frequently activated in some cancers, while others maintain low level activity to achieve optimal cell growth. In cells with endogenously low levels of active Ras, increasing Ras signaling through the ERK and p38 MAPK pathways can cause growth arrest or cell death. Ras requires prenylation – the addition of a 15-carbon (farnesyl) or 20-carbon (geranylgeranyl) group – to keep the protein anchored into membranes for effective signaling. N- and K-Ras can be alternatively geranylgeranylated (GG’d) if farnesylation is inhibited but are …

Regulation Of Protein Degradation In The Heart By Amp-Activated Protein Kinase, Kedryn K. Baskin

Dissertations and Theses (Open Access)

The degradation of proteins by the ubiquitin proteasome system is essential for cellular homeostasis in the heart. An important regulator of metabolic homeostasis is AMP-activated protein kinase (AMPK). During nutrient deprivation, AMPK is activated and intracellular proteolysis is enhanced through the ubiquitin proteasome system (UPS). Whether AMPK plays a role in protein degradation through the UPS in the heart is not known. Here I present data in support of the hypothesis that AMPK transcriptionally regulates key players in the UPS, which, under extreme conditions can be detrimental to the heart. The ubiquitin ligases MAFbx /Atrogin-1 and MuRF1, key regulators of …

Chemosensitization Of Hepatocellular Carcinoma To Gemcitabine By Non-Invasive Radiofrequency Field-Induced Hyperthermia, Mustafa Raoof

Dissertations and Theses (Open Access)

Gemcitabine is a potent nucleoside analogue against solid tumors however drug resistance rapidly emerges. Removal of gemcitabine incorporated in the DNA by repair mechanisms could potentially contribute to resistance in chemo-refractory solid tumors. In this study, we evaluated homologous recombination repair of gemcitabine-stalled replication forks as a potential mechanism contributing to resistance. We also studied the effect of hyperthermia on homologous recombination pathway to explain the previously reported synergy between gemcitabine and hyperthermia. We found that hyperthermia degrades and inhibits localization of Mre11 to gemcitabine-stalled replication forks. Furthermore, gemcitabine-treated cells that were also treated with hyperthermia demonstrate a prolonged passage …

Regulation Of Protein Degradation In The Heart By Amp-Activated Protein Kinase, Kedryn K. Baskin, Kedryn K. Baskin

Dissertations and Theses (Open Access)

The degradation of proteins by the ubiquitin proteasome system is essential for cellular homeostasis in the heart. An important regulator of metabolic homeostasis is AMP-activated protein kinase (AMPK). During nutrient deprivation, AMPK is activated and intracellular proteolysis is enhanced through the ubiquitin proteasome system (UPS). Whether AMPK plays a role in protein degradation through the UPS in the heart is not known. Here I present data in support of the hypothesis that AMPK transcriptionally regulates key players in the UPS, which, under extreme conditions can be detrimental to the heart. The ubiquitin ligases MAFbx /Atrogin-1 and MuRF1, key regulators of …

A Fast Response Highly Selective Probe For The Detection Of Glutathione In Human Blood Plasma, Yixing Guo, Xiaofeng Yang, Lovemore Hakuna, Aabha Barve, Jorge O. Escobedo, Mark Lowry, Robert M. Strongin

Chemistry Faculty Publications and Presentations

A fluorescent probe for glutathione (GSH) detection was developed. Our study indicates a possible mechanism which couples a conjugate addition and micelle-catalyzed large membered ring formation/elimination sequence. This method enables excellent selectivity towards GSH over other biological thiols such as cysteine (Cys) and homocysteine (Hcy). The proposed method is precise with a relative standard deviation (R.S.D) lower than 6% (n = 3) and has been successfully applied to determine GSH in human plasma with recoveries between 99.2% and 102.3%.

Characterization Of Novel Histone H2b Mutants Associated With Chromosome Segregation Defects In Saccharomyces Cerevisiae, Thiruchelvam Rajagopal

Graduate Theses and Dissertations

Histones are small basic proteins that associate with DNA to form the basic unit of chromatin, the nucleosome. Histones H3 and H4 form a tetramer that is bound by two H2A-H2B dimers to form the histone octamer, to which approximately 146 bp of DNA wrap around to form the nucleosome. High resolution structural information and recent advances in the understanding of histone post-translational modifications have illuminated the many regulatory functions chromatin exerts in the cell, from the transcriptional control of gene expression to chromosome segregation. However, the specific role that histones play in these processes is not well understood. Previous …

Genome-Wide Identification Of Conditionally Essential Genes In Salmonella Typhimurium Using Tn-Seq Method, Anita Khatiwara

Graduate Theses and Dissertations

ABSTRACT

As more whole genome sequences become available, there is an increasing need for high-throughput methods that link genes to phenotypes and facilitate discovery of new gene functions. The objective of this study was to develop a high-throughput method to study gene functions in bacteria and use this method to study gene functions of S. enterica serotype Typhimurium (S. Typhimurium) under various environmental conditions encountered during its life cycle. Chapter I of this dissertation reviews the history and evolution of functional genomics in bacteria with focus on Salmonella, along with the recent techniques available. Chapter II, deals with the development …

An Investigation Of Trypanosoma Brucei Hexokinases: Localization, Oligomerization, And Inhibition, April Joice

All Dissertations

Trypanosoma brucei is the causative agent of African sleeping sickness in humans and nagana in livestock. The parasite inhabits multiple environmental niches including the bloodstream of the mammalian host and the mid-gut of the tsetse fly vector. While in the bloodstream of its mammalian host, the organism depends solely on glycolysis for production of ATP. My studies focus on the first enzyme in glycolysis, hexokinase.
T. brucei has two hexokinases, TbHK1 and TbHK2 that are 98.5% identical at the nucleotide level. The hexokinases are expressed in the glycosomes of both procyclic form and bloodstream form parasites. Glycosomes are peroxisome-like organelles …

Stromal-Epithelial Interactions Modulate Cross Talk Between Prolactin Receptor And Her2/Neu In Breast Cancer, Cong Xu

All Dissertations

The tumor microenvironment is a crucial factor in breast tumorigenesis. Tumor epithelial cells maintain 3D structure in tumor stroma and they interact with soluble factors secreted by stromal cells such as cancer associated fibroblasts (CAFs) or directly with the extracellular matrix (ECM). Recent studies have shown that the hormone prolactin (PRL) promotes the proliferation and survival of breast cancer cells in part via the transactivation of human epidermal growth factor receptor 2 (HER2), also known as Neu in rodents. A PRL receptor (PRLR) antagonist, G129R, has been demonstrated not only to be able to directly inhibit PRLR activation but also …