Biochemistry Commons^™

Molecular Characterization Of Integrase-Rna Interactions And Their Role In The Replication Of Hiv-1 And Other Retroviruses, Christian Shema Mugisha

Arts & Sciences Electronic Theses and Dissertations

HIV-1 integrase (IN) enzyme has an emerging non-catalytic role in particle maturation, whichinvolves its binding to the viral genome in virions. Allosteric integrase inhibitors (ALLINIs) and class II integrase substitutions inhibit the binding of IN to the viral genome and cause formation of eccentric non-infectious HIV-1 particles. These viruses are characterized by the mislocalization of the viral ribonucleoprotein complexes between the translucent conical CA lattice and the viral lipid envelope. We have previously demonstrated that IN binding to the viral genome is mediated by basic residues within the C-terminal domain of IN. In the first chapter, we show how basic …

Rna Polymerase Binding Protein A (Rbpa) Regulation Of Mycobacteria Transcription And Sensitivity To Fidaxomicin, Jerome Prusa

Arts & Sciences Electronic Theses and Dissertations

Mycobacterium tuberculosis is the causative agent of the disease tuberculosis (TB) and remains one of the deadliest microorganisms on the planet. The effort to eradicate M. tuberculosis would benefit from the development of novel therapeutics, which requires a detailed understanding of M. tuberculosis physiology. Like all living organisms, M. tuberculosis gene expression requires transcription. Transcription in the phylum Actinobacteria, which includes mycobacteria, is unique because it includes RNA Polymerase Binding Protein A (RbpA) that is essential in both M. tuberculosis and the nonpathogenic model organism Mycobacterium smegmatis. RbpA increases the housekeeping A and housekeeping like B interactions with the RNA …

Protein Synthesis Adaptation To The Au-Rich Transcriptome Of Plasmodium Falciparum, Jessey Lee Erath

Arts & Sciences Electronic Theses and Dissertations

The process of protein synthesis whereby a messenger RNA is decoded into an amino acid chainis conserved among the domains. Fastidious protein synthesis is necessary for organism survival. However, exceptions negatively affecting the mRNA translation cycle – inadvertently or by design – may occur. Polyadenosine tracts are one such motif causing ribosomal stalling and frameshifting in almost all organisms tested thus far; save Plasmodium spp. Thus, with ~60% of their protein-coding genome harboring polyadenosine tracts, the elucidation of such paradigm-breaking adaptations enabling Plasmodium spp. to translate this typically problematic motif without issue is salient from both basic science and clinical …

Understanding The Molecular Mechanisms Of Photoferrotrophy And Phototrophic Extracellular Electron Uptake, Dinesh Gupta

Arts & Sciences Electronic Theses and Dissertations

Several anoxygenic phototrophs grow by utilizing soluble iron or insoluble mixed-valence iron minerals (such as rust) as electron donors to fix carbon dioxide using light energy, a process called photoferrotrophy. Photoferrotrophs can also use electron donors such as poised electrodes that serve as proxies for rust via phototrophic extracellular electron uptake (EEU). Despite the recognition that these two related microbial processes contribute to various biogeochemical cycles such as iron and carbon, the electron uptake mechanisms underlying photoferrotrophy and phototrophic EEU are poorly understood. To address the key knowledge gaps in our understanding of these microbial metabolisms, here we characterized Rhodopseudomonas …

Measuring And Manipulating Tension-Dependent Behavior Of Mechanosensitive Ion Channels, Angela M. Schlegel

Arts & Sciences Electronic Theses and Dissertations

Mechanical forces play critical roles throughout the lives of all organisms and, as such, diverse arrays of mechanotransduction systems have evolved to detect and initiate responses to force. Many mechanotransduction systems consist of mechanosensitive (MS) ion channels, membrane pores that open in response to sufficient mechanical force. My dissertation focuses on both the study and application of force-dependent conformational changes of MS channels. I tested whether charged pore-lining residues R326 and D327 of the Arabidopsis thaliana mitochondrial MS channel MSL1 function in inward rectification or gating kinetics. Mutating these residues showed no effect on MSL1 rectification; however, these residues are …

Activation And Regulation Of The Alkbh3-Ascc Alkylation Repair Pathway, Josh Brickner

Arts & Sciences Electronic Theses and Dissertations

DNA repair is essential to prevent the cytotoxic or mutagenic effects of various types of DNA lesions. These lesions are sensed by distinct pathways to recruit repair factors specific to type of damage. In particular, the ALKBH family of proteins recognizes and repairs specific alkylated lesions, including 1-methyladenine (m1A) and 3-methylcytosine (m3C). A major outstanding question in the field is how the AlkB homologue ALKBH3 and its associated protein partners are recruited to sites of alkylation damage and how this repair activity is regulated. Understanding the upstream signaling events that mediate recognition and repair of DNA alkylation damage is particularly …

Sideromycin Pathway Elucidation: Insights Into Salmycin Biosynthesis, Transport Paradigms, And Drug Release, Gerry Sann Macaraeg Rivera

Arts & Sciences Electronic Theses and Dissertations

Antibiotic resistance is an increasing threat in today’s society. In order to overcome resistant bacteria, it is necessary to discover new drugs with novel mechanisms of action. This work focuses on the sideromycin pathway, encompassing the biosynthetic production, mechanism of entry and hydrolysis-mediated drug release. Sideromycins are an interesting approach to combat the rise of antibiotic resistance since they provide a different avenue that overcomes problems that arise when entering the cell. The dissertation is separated into distinct sections dealing with the various areas of interest in the sideromycin pathway, particularly for the sideromycin, salmycin, produced by Streptomyces violaceus. The …

The Impact Of Mrna Structure On Trna Selection And Ribosome Rescue, Erica Nicole Thomas

Arts & Sciences Electronic Theses and Dissertations

The faithful and rapid translation of proteins from genetic information is an essential feature of the ribosome. The general process of tRNA selection is governed by the ability of the ribosome to select for the aminoacylated tRNA (aa-tRNA) that matches the codon in its A-site. The efficiency and accuracy of this selection depends on the ability of nucleotides to form proper hydrogen bonds. While much is known about how chemical alterations of tRNA and rRNA can impact the fidelity of translation, less is known about how similar changes to mRNA affect decoding. In this work, we describe several studies aimed …

Development Of Lc-Ms For The Identification And Characterization Of Non-Adjacent Dna Photoproduct Formation In G-Quadruplex Forming Sequences, Claudia Posadas

Arts & Sciences Electronic Theses and Dissertations

Ultraviolet light is well known to induce cyclobutane pyrimidine dimers (CPD) and pyrimidine (6–4) pyrimidone photoproducts in duplex DNA, which interfere with DNA replication and transcription. Recently, a new class of DNA photoproducts known as anti cyclobutanepyrimidine dimers have been discovered, which form in G-quadruplex forming sequences in solution. G-quadruplex structures have been proposed to form in human DNA telomeres and certain promoters in vivo but evidence for their existence has been lacking. Since anti-cyclobutante pyrimidine dimers have been shown to form in G-quadruplex forming sequences, their formation in irradiated human cells could be used to confirm the existence …

Regulation Of Gene Expression By Rna Binding Proteins And Micrornas, Kyle Cottrell

Arts & Sciences Electronic Theses and Dissertations

Regulation of gene expression is essential to life. Post-transcriptional regulation of gene expression is a complex process with many inputs that lead to changes in localization, translation and stability of mRNAs. The translation and stability of many mRNAs is regulated by cis-elements, such as mRNA-structure or codon optimality; and by trans-acting factors such as RBPs and miRNAs. Here I report on the complex interactions between RBPs, miRNAs and characteristics of their target mRNAs in respect to effects on translation and RNA stability.

Using a reporter based approach we studied modulation of microRNA-mediated repression by various mRNA characteristics. We observed the …

Mechanisms And Regulation Of Resection In Dna Damage Response, Sharad C. Paudyal

Arts & Sciences Electronic Theses and Dissertations

Deoxyribonucleic acid (DNA) encodes genetic information essential for cell survival and function. However, it is constantly under assault from endogenous and exogenous damaging agents that not only threaten our own survival but also affect the faithful transmission of genetic information to our offspring. Double-strand breaks (DSBs) are one of the most hazardous forms of DNA damage, which if unrepaired or improperly repaired could lead to plethora of systemic human diseases including cancer. To deal with this problem, cells have evolved with a mechanism called DNA damage response (DDR) to detect, signal, and repair the breaks by inducing multiple cellular events. …

Mechanisms Of G Protein Regulation By Rgs Proteins And Small Molecule Inhibitors, Stanley Michinobu Kanai

Arts & Sciences Electronic Theses and Dissertations

G protein coupled receptors transduce diverse extracellular signals like hormones, neurotransmitters, and photons to specific cellular responses through heterotrimeric G proteins. G proteins activate numerous effectors and signal transduction pathways, and therefore the regulation of G proteins is crucial for faithful propagation of specific cellular and physiological responses. A better understanding of the mechanisms that regulate G proteins should provide new insight into signaling pathways that govern healthy and disease states, and also provide opportunities for discovery of novel therapeutic targets.Regulator of G protein signaling (RGS) proteins are crucial regulators of G proteins, for they control amplitude and duration of …

Structural, Biophysical, And Functional Studies Of Trem2 In Neurodegenerative Disease, Daniel L. Kober

Arts & Sciences Electronic Theses and Dissertations

Alzheimer's disease (AD) and other neurodegenerative diseases present a large and growing challenge to global health. The immune system, particularly the innate immune system, is increasingly recognized as having a major role in these pathologies. The innate immune system is responsible to contain disease and promote healing. However, immune misregulation exacerbates disease. The innate immunomodulatory receptor Triggering receptor expressed on myeloid cells-2 (TREM2) is expressed on myeloid cells such as dendritic cells, macrophages, and in the brain, on microglia. TREM2 is a single-pass transmembrane receptor with an extracellular Ig domain that mediates ligand binding. This protein regulates inflammation in vitro …

The Rpl13a Snorna U33 Forms Novel Snornps During Lipotoxicity, Miquia Sherree Henderson

Arts & Sciences Electronic Theses and Dissertations

Lipid overload contributes to the pathogenesis of diabetic complications, causing tissue damage and cell death in a number of organ systems. This process is termed lipotoxicity. Animal and cell culture studies have demonstrated that oxidative stress and endoplasmic reticulum stress are major pathways engaged in the lipotoxic response. However, the molecular mechanisms of lipotoxicity are not well understood. A genetic screen revealed that small nucleolar RNAs (snoRNAs) encoded in the introns of the Rpl13a locus are critical for cell death in response to lipotoxicity. Initial studies have suggested that the Rpl13a snoRNAs function in this pathway through non-canonical modes of …