Biochemistry, Biophysics, and Structural Biology Commons^™

Biochemical Analyses Of Udgx-A Crosslinking Uracil-Dna Glycosylase, Chuan Liang

All Dissertations

DNA base damage is common due to exposure to various endogenous and exogenous factors. To repair the base lesions, such as uracil from cytosine deamination, enzymes from the uracil-DNA glycosylase (UDG) superfamily are critical, which can recognize the damaged base and initiate the base excision repair (BER) pathway. There used to be six families of proteins identified in the UDG superfamily until a new member, UDGX, was found in Mycobacterium smegmatis, which is a unique DNA-crosslinking UDG. In this dissertation work, a series of biochemical analyses of the newly found UDGX are performed, including the analyses of structures, functions, …

Characterizing The Structural, Biophysical And Functional Effects Of S-Glutathionylation On Stim1 Ca2+ Sensing, Christian Michael Sirko

Electronic Thesis and Dissertation Repository

Stromal interaction molecule 1 (STIM1) is an endo/sarcoplasmic reticulum (ER/SR) calcium (Ca²⁺) sensing protein that initiates cytoplasmic Ca²⁺ influx via store-operated calcium entry (SOCE). STIM1, in conjunction with Orai, a plasma membrane (PM) protein, function as mediators of SOCE through the formation of calcium-release activated calcium (CRAC) channels. S-Glutathionylation of STIM1 at Cys56 has been shown to evoke constitutive Ca²⁺ entry in DT40 cells, however no studies have carefully investigated the biophysical and structural effects of this covalent modification to the luminal domain, which are critical for understanding the molecular mechanism underlying the regulation of …

Engineering Of Recombinant Fortilin For Structure Activity Studies, Maranda S. Cantrell

Boise State University Theses and Dissertations

Cardiovascular disease (CVD) is the leading cause of death worldwide affecting approximately 40% of all adults over the age of 20 and is responsible for an economic burden upwards of $3 billion annually. Treatments for CVD are limited to either hypertension medication to treat symptoms, and/or statin-based drugs to reduce low-density lipoprotein (LDL) cholesterol formation. However, recent studies suggest that approximately 50% of patients diagnosed with CVD have normal to low LDL cholesterol levels. Therefore, a critical need exists to develop new treatments for CVD that are independent of cholesterol lowering statins. Fortilin, also known as translationally controlled tumor protein …

Unveiling Global Roles Of G-Quadruplexes And G4-22 In Human Genetics, Ruth Barros De Paula

Dissertations & Theses (Open Access)

G-quadruplexes are non-B DNA structures formed by four or more runs of repeated guanines that confer unique features to living organism’s genomes. These sequences are enriched in regulatory regions, such as promoters and 5’ UTRs, and have distinct regulatory roles in both health and disease states. Even though previous studies showed the impact of G4 in gene expression, none of them summarized the location-specific effect of G4. Also, there is no broad understanding about the most common G4 repeat in the human genome, named here as G4-22, and how it links to the evolution of mammals and their biology. In …

Exploring The Dynamics Of Biological Macromolecules At Angstrom Scale, Calvin Foss

Honors Thesis

This thesis studied the Guanylate Kinase (GK) enzyme, which catalyzes the reaction of ATP into ADP, using nano-rheological techniques. A unique experimental setup was created in order to observe the conformational dynamics of the biological macromolecules. An oscillatory force was applied by attaching enzymes to a gold-coated surface and gold nanoparticles. An additional gold-coated surface was placed on top of the setup in order to create a parallel plate capacitor configuration. An oscillatory voltage was then applied across the capacitor to drive the gold nanoparticles and exert a force on the enzymes. The setup detected the ensemble averaged movement of …

Discovery And Characterization Of Small Molecule Inhibitors Of Bromodomains, Md Rezaul Karim

USF Tampa Graduate Theses and Dissertations

The epigenetic “reader” modules bromodomains (BRDs) exert their diverse cellular functions through the recognition of acetylated lysines on histones and other proteins. Small molecule inhibitors of bromodomains have emerged as a promising therapeutic strategy to treat atherosclerotic cardiovascular diseases and cancers. Therefore, a large number of small molecule bromodomain inhibitors have been developed in the last decade, some of which are currently being assessed in the clinic. However, the success of bromodomain inhibitors is currently limited to the bromodomain and extra-terminal domain (BET) subfamily.

To address these, bromodomains outside the BET subfamily (non-BETs) such as TAF1, BRD7/9, TRIM28, and BRD8 …

Structural And Functional Characterization Of Cazyme And Cazyme-Related Proteins From: Bacteroides Thetaiotaomicron And Porphyromonas Gingivalis: Two Abundant Colonizers Of The Human Microbiome, James Stevenson

Theses and Dissertations (Comprehensive)

The human body consists of approximately 30 trillion cells, while non-human microbes that reside on and within the body outnumber human somatic cells by a factor of 1.3 – 2.3. The interplay between our cells and those of the colonizing microorganisms affect physiology in a multitude of ways, both beneficial and detrimental. Microbes found in the oral cavity, such as the Red Complex member Porphyromonas gingivalis, are associated with pathology, namely periodontal diseases including gum deterioration, tooth decay, and loss of underlying alveolar bone. At the other end of the gastrointestinal tract, microbes such as Bacteroides thetaiotaomicron are found …

Effects Of The Dihydrouracil Lesion On Dna Using 1h/31p 1d And 2d Solution Nmr, Benjamin M. Boyd

MSU Graduate Theses

The effects of the dihydrouracil lesion in DNA were studied using two dimensional NMR spectroscopy. The sequence used was based off of the Drew-Dickerson Dodecamer, with the cytosine in the three position replaced by a dihydrouracil. All of the nonexchangeable proton chemical shifts, with the exception of the H2, H5’, and H5’’, of the lesioned DNA were identified using NOESY spectra and then compared to the chemical shift values of the Drew Dickerson Dodecamer. The largest differences in chemical shifts were observed in the nucleotides neighboring the lesion, both within the strand and on the opposite strand. The imino exchangeable …

Electron Decoupling With Chirped Microwave Pulses For Magic Angle Spinning Dynamic Nuclear Polarization Nuclear Magnetic Resonance Spectroscopy, Edward Paul Saliba

Arts & Sciences Electronic Theses and Dissertations

Dynamic nuclear polarization (DNP) is a method of generating hyperpolarization of nuclear spins for nuclear magnetic resonance (NMR) spectroscopy. Coherent, time domain techniques make the possibility of DNP directly to spins of interest at room temperature and higher feasible in magic angle spinning (MAS) NMR, allowing for optimal experimental repetition times to be limited by the T_1 of the electron, rather than a much longer T_1DNP, with excellent resolution. The strong hyperfine couplings that make such direct DNP transfers possible, however, can lead to short nuclear relaxation times that result in broadening of nuclear resonances and reduce sensitivity. This dissertation …

Structural Studies On Calcium/Calmodulin-Dependent Activation Of Eukaryotic Elongation Factor 2 Kinase, Kwangwoon Lee

Dissertations, Theses, and Capstone Projects

Eukaryotic elongation factor 2 kinase (eEF-2K) is a key modulator of the rate of protein synthesis. Activated by calcium-loaded calmodulin (Ca²⁺-CaM), eEF-2K phosphorylates its only known physiological substrate, eEF-2, on a specific threonine residue (Thr-56). Phosphorylated eEF-2 has reduced affinity for the ribosome, and results in a significant decrease in the rate of translation elongation. Modulation of the rate of translation elongation plays a crucial role in proteostasis – adequate regulation of protein synthesis, protein folding, and protein degradation that greatly influences cellular growth and survival. Binding of Ca²⁺-CaM triggers activation of eEF-2K and remains intact …

A Journey Towards Understanding Biology Holistically At The Nanoscale, Trevor Moser

Dissertations, Master's Theses and Master's Reports

Characterizing biological processes with microscopy techniques that allow one to directly visualize the complexity of life is an important component of understanding both physiological function and structure. The wide spectrum of biological structures from individual proteins to whole ecosystems necessitates that multiple techniques are used to characterize all levels of organization. While existing techniques cover portions of this spectrum, continued improvement of established methods and development of new techniques is needed. This dissertation outlines my journey in enabling new approaches for imaging biosystems at various scales. Chapters 1 and 2 provide motivation for bioimaging and background for the use of …

Rep-Dna Complexes And Their Role In Aav Dna Transactions, Vishaka Santosh

Theses and Dissertations

Adeno-associated Virus (AAV) Rep proteins are multifunctional proteins that carry out various DNA transactions required for the life cycle of AAV. The Rep proteins have been found to be important for genome replication, gene regulation, site-specific integration and play an essential role in genome packaging. There are two main groups of Rep proteins: large and small Reps; both groups are SF3 helicase family members. During DNA packaging, studies have shown that the small Rep proteins are critical to produce fully packed particles. Using stopped-flow kinetic analysis, we show a significant difference in helicase activity between the small and large Rep …

Intrinsic Disorder Where You Least Expect It: The Incidence And Functional Relevance Of Intrinsic Disorder In Enzymes And The Protein Data Bank, Shelly Deforte

USF Tampa Graduate Theses and Dissertations

Intrinsically disordered proteins (IDPs) and intrinsically disordered protein regions (IDPRs) exist as interconverting conformational ensembles, without a single fixed three-dimensional structure in vivo. The focus in the literature up to this point has been primarily on IDPs that are mostly or entirely disordered. Therefore, we have an incomplete understanding of the incidence and functional relevance of IDPRs in proteins that have regions of both order and disorder. This work explores these populations, by examining IDPRs in the Protein Data Bank (PDB) and in enzymes. By applying disorder prediction methods combined with an analysis of missing regions in crystal structure data, …

Structural Mechanisms Of Glucan Phosphatase Activity In Starch Metabolism, David A. Meekins

Theses and Dissertations--Molecular and Cellular Biochemistry

Starch is a water-insoluble glucose biopolymer used as an energy cache in plants and is synthesized and degraded in a diurnal cycle. Reversible phosphorylation of starch granules regulates the solubility and, consequentially, the bioavailability of starch glucans to degradative enzymes. Glucan phosphatases release phosphate from starch glucans and their activity is essential to the proper diurnal metabolism of starch. Previously, the structural basis of glucan phosphatase activity was entirely unknown. The work in this dissertation outlines the structural mechanism of activity of two plant glucan phosphatases called Starch EXcess4 (SEX4) and Like Sex Four2 (LSF2). The crystal structures of SEX4 …

Structure, Dynamics, And Evolution Of The Intrinsically Disordered P53 Transactivation Domain, Wade Michael Borcherds

USF Tampa Graduate Theses and Dissertations

in numerous disease states, including cancers and neurodegenerative diseases. All proteins are dynamic in nature, occupying a range of conformational flexibilities. This inherent flexibility is required for their function, with ordered proteins and IDPs representing the least flexible, and most flexible, respectively. As such IDPs possess little to no stable tertiary or secondary structure, they instead form broad ensembles of heterogeneous structures, which fluctuate over multiple time scales. Although IDPs often lack stable secondary structure they can assume a more stable structure in the presence of their binding partners in a coupled folding binding reaction.

The phenomenon of the dynamic …