Biochemistry Commons^™

Functional Characterization Of Cancer-Associated Dna Polymerase Ε Variants, Stephanie R. Barbari

Theses & Dissertations

Replicative DNA polymerases ε (Polε) and δ (Polδ) achieve high fidelity DNA synthesis through a precise balance of polymerization and exonucleolytic proofreading. Errors that escape proofreading are corrected by DNA mismatch repair (MMR). Ultramutated human cancers with proficient MMR carry alterations in the exonuclease domain of Polε, which were initially predicted to abolish proofreading. However, functional studies in yeast of the most recurrent Polε-P286R variant suggested defects beyond a loss of exonuclease activity. Indeed, biochemical analysis of the yeast Polε-P286R analog revealed increased polymerization capacity in addition to decreased proofreading, which enables efficient mismatch extension and bypass of replication-blocking non-B …

Erecta Family Genes Regulate The Shoot Apical Meristem And Organ Formation, Daniel A. Degennaro

Doctoral Dissertations

Plants are sessile and must adjust their organ growth to their environments. A reservoir of stem cells in the shoot apical meristem (SAM) supplies cells for differentiation into organs. The SAM must balance organ production with stem cell maintenance. The ERECTA family (ERfs) encodes the leucine-rich repeat receptor-like kinases ERECTA (ER), ERECTA-LIKE 1 (ERL1), and ERL2. ERf signaling regulates organ initiation and stem cell maintenance. Results presented in this work include the following:

1) WUSCHEL (WUS) and CLAVATA3 (CLV3) make up a negative feedback loop to maintain SAM size. WUS and CLV3 expression localization is critical for …

Deciphering The Role Of Hsp110 Chaperones In Diseases Of Protein Misfolding, Unekwu M. Yakubu

Dissertations & Theses (Open Access)

Molecular chaperones maintain protein homeostasis (proteostasis) by ensuring the proper folding of polypeptides. Loss of proteostasis has been linked to the onset of numerous neurodegenerative disorders including Alzheimer’s, Parkinson’s, and Huntington’s disease. Hsp110 is a member of the Hsp70 class of molecular chaperones and acts as a nucleotide exchange factor (NEF) for Hsp70, the preeminent Hsp70-family protein folding chaperone. Hsp110 promotes rapid cycling of ADP for ATP, allowing Hsp70 to properly fold nascent or unfolded polypeptides in iterative cycles. In addition to its NEF activity, Hsp110 possesses an Hsp70-like substrate binding domain (SBD) whose biological roles are undefined. Previous work …

Insights Into Halophilic Microbial Adaptation: Analysis Of Integrons And Associated Genomic Structures And Characterization Of A Nitrilase In Hypersaline Environments, Sarah Sonbol

Theses and Dissertations

Hypersaline environments are extreme habitats that can be exploited as biotechnological resources. Here, we characterized a nitrilase (NitraS-ATII) isolated from Atlantis II Deep brine pool. It showed higher thermal stability and heavy metal tolerance compared to a closely related nitrilase.

We also studied integrons in halophiles and hypersaline environments. Integrons are genetic platforms in which an integron integrase (IntI) mediates the excision and integration of gene cassettes at specific recombination sites. In order to search for integrons in halophiles and hypersaline metagenomes, we used a PCR-based approach, in addition to different bioinformatics tools, mainly IntegronFinder.

We found that integrons and …

C. Elegans Response To Cadmium Toxicity, Brian James Earley

Arts & Sciences Electronic Theses and Dissertations

Cadmium is an environmental pollutant and significant health hazard that is similar to the physiological metal zinc. Residing in the same group of the periodic table, cadmium and zinc share chemical characteristics that are important for their industrial uses in electroplating, batteries, pigments, and metal alloys. The similarities of ionic cadmium and zinc have significant repercussions on biological systems. While it has long been clear that cadmium is toxic to biological systems, the mechanisms of cadmium toxicity remain poorly understood. In contrast, mechanisms of zinc homeostasis have been elucidated in growing detail. In C. elegans high zinc homeostasis is regulated …

Mucin And Splice Variant Profiles Of Pancreatic Adenocarcinoma Predict Patient Survival And Subtyping, Christopher M. Thompson

Theses & Dissertations

PDAC is a pancreatic epithelial malignancy and demonstrates aggressive progression and bleak patient prognosis. Despite decades of research, the evolution of novel diagnostics and intervention modalities for PDAC is stagnant. This dissertation explores the characteristic aberrant and elevated expression of mucins in PDAC. Beginning with the hypothesis that mucins are associated with disease aggressiveness, analysis of PDAC patient survival in TCGA revealed no associations between single mucin expression and patient survival. This led to the underlying issue of PDAC tumor cellularity since this disease demonstrates variability in the proportion of cancer cells within the tumor. Tumor purity assessed with the …

Development Of In-Silico Pipelines For Identification And Characterization Of Biomarker Panels And Therapeutic Interventions In Gastro-Intestinal (Gi) Cancers, Pranita Atri

Theses & Dissertations

Gastro-intestinal (GI) malignancies, including gastric, colorectal, and pancreatic cancers, have maintained their high overall mortality due to a lack of prognostic and diagnostic biomarkers and potential therapeutic modalities. While efforts have been made to improve both early detection and therapeutic interventions in these cancers, failure of conventional approaches have proven to be a big challenge, and alternate approaches are needed. Computational biology approaches owing to lesser time and more per target success rate offer a unique solution here. The current study explored the use of computational biology techniques to study the various aspects relating to GI malignancies. First, we sought …

Discovery Of Novel Ubiquitin- And Methylation-Dependent Interactions Using Protein Domain Microarrays, Jianji Chen

Dissertations & Theses (Open Access)

Post-translational modifications (PTMs) drive signal transduction by interacting with "reader" proteins. Protein domain microarray is a high throughput platform to identify novel readers for PTMs. In this dissertation, I applied two protein domain microarrays identifying novel readers for histone H2Aub1 and H2Bub1, and H3TM K4me3. Ubiquitinations of histone H2A at K119 (H2Aub1) and histone H2B at K120 (H2Bub1) function in distinct transcription regulation and DNA damage repair pathways, likely mediated by specific "reader" proteins. There are only two H2Aub1-specific readers identified and no known H2Bub1-specific readers. Using a ubiquitin-binding domain microarray, I discovered the phospholipase A2-activating protein (PLAA) PFU domain …

Validation Of Anti-Oxidative Stress Genes From Genome-Wide Screening Of Escherichia Coli, Carson Ercanbrack

Chemistry & Biochemistry Undergraduate Honors Theses

The primary purpose of this project is to evaluate the genes that play a role in the oxidative stress response in Escherichia coli. In doing so, the entire genome of E. coli was subject to throughput in which individual genes were determined to have a role in the bacteria’s oxidative stress response. Moreover, this project focused on the validation of the genes that were able to pass the initial throughput stage. The genes were subject to two forms of validation. In the first validation technique, candidate genes were overexpressed and minimum inhibitory concentrations of hypochlorous acid were taken. Following, a …

Understanding And Exploiting Protein Allostery And Dynamics Using Molecular Simulations, Sukrit Singh

Arts & Sciences Electronic Theses and Dissertations

Protein conformational landscapes contain much of the functionally relevant information that is useful for understanding biological processes at the chemical scale. Understanding and mapping out these conformational landscapescan provide valuable insight into protein behaviors and biological phenomena, and has relevance to the process of therapeutic design.

While structural biology methods have been transformative in studying protein dynamics, they are limited by technicallimitations and have inherent resolution limits. Molecular dynamics (MD) simulations are a powerful tool for exploring conformational landscapes, and provide atomic-scale information that is useful in understanding protein behaviors. With recent advances in generating datasets of large timescale simulations …

Functional Characterization Of Threonine 49 Phosphorylation Of Cytochrome C, Antoine Khobeir

Wayne State University Theses

Cytochrome c (Cytc) is a pivotal multifunctional mitochondrial protein that serves as a single electron carrier between complexes III and IV of the electron transport chain. It has important roles in both cellular respiration and apoptosis. The novel Thr49 (T49) phosphorylation of Cytc likely affects mitochondrial respiration, membrane potential, ROS production, ATP production, and apoptosis. Based on the functional characterization of previously mapped phosphorylation sites (Tyr97, Tyr48, Thr28, Ser47, Thr58) of the lab, we hypothesize that T49 phosphorylation will lead to controlled respiration, optimal intermediate mitochondrial membrane potential, lower ROS production, and inhibition of apoptosis compared to unphosphorylated Cytc. Here …

Mnrr1: Understanding The Role Of A Novel Mitochondrial-Nuclear Regulator, Stephanie L. Gladyck

Wayne State University Dissertations

Mitochondria are complex organelles that generate most of the energy required to sustain life and function in metabolic and signaling pathways required to maintain cellular homeostasis. MNRR1 (mitochondrial nuclear retrograde regulator 1 or CHCHD2) is a small, bi-organellar twin CX9C protein that is emerging as an important regulator of mitochondrial function, apoptosis, and cellular stress by participating in mitochondrial-nuclear crosstalk. Our lab has previously shown that in the mitochondria, MNRR1 regulates complex IV (Cytochrome c oxidase or COX) and is able to finetune the oxidase function through phosphorylation status. We have also shown that during stress, mitochondrial MNRR1 levels deplete, …

The Receptor Basis Of Serotonergic Modulation In An Olfactory Network, Tyler Ryan Sizemore

Graduate Theses, Dissertations, and Problem Reports

Neuromodulation is a nearly ubiquitous process that endows the nervous system with the capacity to alter neural function at every level (synaptic, circuit, network, etc.) without necessarily adding new neurons. Through the actions of neuromodulators, the existing neural circuitry can be adaptively tuned to achieve flexible network output and similarly dynamic behavioral output. However, despite their near ubiquity in all sensory modalities, the mechanisms underlying neuromodulation of sensory processing remain poorly understood. In this dissertation, I address three main questions regarding the mechanisms of one modulator (serotonin) within one sensory modality (olfaction). I begin by establishing a "functional atlas" of …

Genetic Analysis Of Cellular Adhesion In Arabidopsis Thaliana, Andrew Close Bolender

Honors Projects

Plant cell adhesion is mediated by the extracellular matrix (ECM) or cell wall and plays an important role in plant morphogenesis and development. The amount, modification, and cleavage of pectin in the cell wall are major contributors to the adhesive properties of the ECM. To gain a more complete picture of plant cell adhesion processes, Arabidopsis thaliana seedlings were previously mutagenized and screened for hypocotyl adhesion defects. Genomic sequencing of one plant exhibiting an adhesion defect, isolate 242, showed that two mutations, one in cellulose synthase (CesA1) and another in a sugar transporter, are candidates for the causative mutation. This …

Applications Of Machine Learning In Microbial Forensics, Ryan B. Ghannam

Dissertations, Master's Theses and Master's Reports

Microbial ecosystems are complex, with hundreds of members interacting with each other and the environment. The intricate and hidden behaviors underlying these interactions make research questions challenging – but can be better understood through machine learning. However, most machine learning that is used in microbiome work is a black box form of investigation, where accurate predictions can be made, but the inner logic behind what is driving prediction is hidden behind nontransparent layers of complexity.

Accordingly, the goal of this dissertation is to provide an interpretable and in-depth machine learning approach to investigate microbial biogeography and to use micro-organisms as …

Sars-Cov-2: An Investigation On Mutagenicity And Its Effects On Infectivity And Mortality, Tyler Elliott Silverwood

Honors Theses and Capstones

SARS-CoV-2, the etiological agent of the COVID-19 pandemic, has rapidly become a worldwide public health concern. Classified as a betacoronavirus, it is the third human coronavirus (HCoV) to emerge in the 21st century that causes severe disease, alongside SARS-CoV and MERS-CoV. The genome consists of open reading frames encoding accessory proteins and four structural proteins, including the spike protein which is a key determinant of host cell tropism. Mutations within the genome, particularly the spike gene, have been linked in-vitro to increased binding affinity to the human receptor angiotensin-converting enzyme 2 (hACE2), increased fitness in human hosts, and immune evasion. …