Structural Biology Commons^™

Swarna Ramaswamy_Thesis, Swarna S. Ramaswamy

Dissertations and Theses (Open Access)

STRUCTURAL INVESTIGATIONS OF LIGAND GATED ION CHANNELS

Swarna Ramaswamy, B.S

Advisor: Vasanthi Jayaraman, Ph.D.

Ion channels form an integral part of membrane proteins. In the nervous system including the central and the peripheral nervous system, ligand gated ion channels form a very important part of intercellular communications. They receive chemical signals and convert them to electrical signal, mainly by allowing ion passage across the cell membrane. Ion passage also translates into downstream signaling events. Faithful translation of these signals and transmittance is crucial for several physiological functions, implying that irregular ion channel function could lead to serious consequences.

This thesis …

Numerical Simulations Of In Vitro Nanoparticle Toxicity – The Case Of Poly(Amido Amine) Dendrimers., Marcus Maher, Pratap Naha, Sourav Prasanna Mukherjee, Hugh Byrne

Articles

A phenomenological rate equation model is constructed to numerically simulate nanoparticle uptake and subsequent cellular response. Polyamidoamine dendrimers (generations 4-6) are modelled and the temporal evolution of the intracellular cascade of; increased levels of reactive oxygen species, intracellular antioxidant species, caspase activation, mitochondrial membrane potential decay, tumour necrosis factor and interleukin generation is simulated, based on experimental observations.

The dose and generation dependence of several of these response factors are seen to well represent experimental observations at a range of time points. The model indicates that variations between responses of different cell-lines, including murine macrophages, human keratinocytes and colon cells, …

Development Of Electron Microscopy Analysis And Simulation Tools For Nanohub, Mingxuan Lu, Chang Wan Han, Benjamin P. Haley, Volkan Ortalan

The Summer Undergraduate Research Fellowship (SURF) Symposium

Electron microscopy has a crucial role in the field of materials science and structural biology. Although electron microscopy gives lots of important results and findings, some additional simulations and image processing/reconstruction is required to get more information from the data that are collected from the experiments. For this purpose, researchers are using IMOD¹ and QSTEM² for electron microscopy analysis and simulation. IMOD is a set of programs used for tomographic reconstruction and 3D visualization and QSTEM is used for quantitative simulations of TEM and STEM images. However, IMOD and QSTEM are hard to install or use for beginners …

Developing Crosslinking Constructs Of Protein Kinase R, Prisma E. Lopez

Honors Scholar Theses

Protein Kinase R (PKR) is a key component of the innate immune antiviral response. PKR is activated upon binding to dsRNA. However, recent studies have shown that PKR can also bind to and become activated by duplex RNAs containing complex secondary structure. The mechanism of PKR binding and activation by these RNAs is currently not known. The approach taken here to determine the mechanism of PKR binding by these RNAs is through the development of PKR constructs that are capable of covalently binding to RNAs. Constructs were created by site-specific incorporation of an unnatural, photoactivatable amino acid within PKR. These …

A Comparison Of Angiography Versus Intravascular Ultrasound In The Treatment Of Peripheral Arterial Disease, Michael Pompliano

Senior Theses

Peripheral Arterial Disease is a growing epidemic throughout the United States. It is estimated that 8 to 12 million Americans currently suffer from PAD, a disease of the circulatory system that limits blood flow to your hands and feet. This limited blood flow is due to the narrowing of the arteries that supply blood throughout your body and can disrupt the balance of the nerves and tissues that make up your extremities. If left untreated, it can cause irreparable, life- threatening damage that may result in amputation of the diseased limb. Although the mechanism of PAD is known and well …

Mutagenesis Of 8-Oxoguanine Adjacent To An Abasic Site In Escherichia Coli Cells Proficient Or Deficient In Dna Polymerase Iv, Savas T. Tsikis

Honors Scholar Theses

It is well established that clustered DNA damages or multiply damaged sites (MDS) are the result of ionizing radiation and that they are characterized by an enhanced mutagenic potential. As a model MDS, we have evaluated the mutagenic and cytotoxic properties of the ubiquitous oxidative DNA damage 8-oxoguanine (G^8-oxo) adjacent to the abasic site lesion (Z) using a single stranded M13mp7L2 vector. The recombinant DNA was used to transform wild type E. coli strains and strains deficient in the translesion DNA polymerase of the Y-family, DNA polymerase IV, in the presence or absence of SOS induction. The percent …

Clpxp Modulates Cell Growth And Morphology In Cell Shape Mutants Of E.Coli, Ryann Murphy

Senior Honors Projects

ClpXP modulates cell growth and morphology in cell shape mutants of E. coli

Ryann Murphy¹ and Jodi L. Camberg¹

¹University of Rhode Island, Department of Cell and Molecular Biology, Kingston, RI, 02881

Penicillin Binding Proteins (PBPs) are a family of prokaryotic membrane proteins named for their propensity to bind the antibiotic penicillin and are involved in remodeling and deposition of peptidoglycan. In wild type Escherichia coli cells, the uniform rod shape is conserved across generations. E.coli cells containing multiple deletions of Low Molecular Weight (LMW) PBPs exhibit irregular shapes. LMW PBP5 (dacA) is a potential …

Comparing And Informing Morphological Species Identifications And Boundaries In Arthropod Gut-Dwelling Protists Using Molecular Phylogenetic Analyses, Mason Hinchcliff, Nicole Reynolds, Eric Tretter, Dustin Heeney, Justin Gause, Tyler Pickell, Prasanna Kandel

College of Arts and Sciences Presentations

Trichomycetes are fungal and protistan symbionts of arthropods and have been found in marine, freshwater, and terrestrial habitats on every continent except Antarctica. Minimally, trichomycetes associate commensally with their immature aquatic hosts (including black flies, mayflies, stoneflies, isopods, and others) attaching to the chitinous lining of the mid or hindgut. Classified with trichomycetes are Paramoebidium, a group of protists which associate in an obligate manner with their hosts. To date, 16 species of Paramoebidium have been identified by morphological approaches. These descriptions have included characterization and discrimination of species based on thallus (body) length and width, differences in the …

Structural Dynamics Of A Mitochondrial Trna Possessing Weak Thermodynamic Stability, Hari Bhaskaran, Takaaki Taniguchi, Takeo Suzuki, Tsutomu Suzuki, John J. Perona

Chemistry Faculty Publications and Presentations

Folding dynamics are ubiquitously involved in controlling the multivariate functions of RNAs. While the high thermodynamic stabilities of some RNAs favor purely native states at equilibrium, it is unclear whether weakly stable RNAs exist in random, partially folded states or sample well-defined, globally folded conformations. Using a folding assay that precisely tracks the formation of native aminoacylable tRNA, we show that the folding of a weakly stable human mitochondrial (hmt) leucine tRNA is hierarchical with a distinct kinetic folding intermediate. The stabilities of the native and intermediate conformers are separated by only about 1.2 kcal/mol, and the species are readily …

Pathoscope 2.0: A Complete Computational Framework For Strain Identification In Environmental Or Clinical Sequencing Samples., Changjin Hong, Solaiappan Manimaran, Ying Shen, Joseph F Perez-Rogers, Allyson L Byrd, Eduardo Castro-Nallar, Keith A Crandall, William Evan Johnson

Computational Biology Institute

BACKGROUND: Recent innovations in sequencing technologies have provided researchers with the ability to rapidly characterize the microbial content of an environmental or clinical sample with unprecedented resolution. These approaches are producing a wealth of information that is providing novel insights into the microbial ecology of the environment and human health. However, these sequencing-based approaches produce large and complex datasets that require efficient and sensitive computational analysis workflows. Many recent tools for analyzing metagenomic-sequencing data have emerged, however, these approaches often suffer from issues of specificity, efficiency, and typically do not include a complete metagenomic analysis framework.

RESULTS: We present PathoScope …

Characteristics And Prediction Of Rna Structure., Hengwu Li, Daming Zhu, Caiming Zhang, Huijian Han, Keith A Crandall

Computational Biology Institute

RNA secondary structures with pseudoknots are often predicted by minimizing free energy, which is NP-hard. Most RNAs fold during transcription from DNA into RNA through a hierarchical pathway wherein secondary structures form prior to tertiary structures. Real RNA secondary structures often have local instead of global optimization because of kinetic reasons. The performance of RNA structure prediction may be improved by considering dynamic and hierarchical folding mechanisms. This study is a novel report on RNA folding that accords with the golden mean characteristic based on the statistical analysis of the real RNA secondary structures of all 480 sequences from RNA …

Split-Spinach Monitoring Of Rna Aptamer Assembly, Tucker A. Rogers, Grant Andrews

Honors Projects

As insights into RNA’s many diverse cellular roles continue to be gained, interest and applications in RNA self-assembly and dynamics remain at the forefront of structural biology. The bifurcation of functional molecules into nonfunctional fragments provides a useful strategy for controlling and monitoring cellular RNA processes and functionalities. Herein we present the bifurcation of the preexisting Spinach aptamer and demonstrate its utility as a novel split aptamer system for monitoring RNA self-assembly as well as the processing of pre-short interfering substrates. We show for the first time that the Spinach aptamer can be divided into two nonfunctional halves that, once …

Investigating Structure And Protein-Protein Interactions Of Key Post-Type Ii Pks Tailoring Enzymes, Theresa E. Downey

Theses and Dissertations--Pharmacy

Type II polyketide synthase (PKS) produced natural products have proven to be an excellent source of pharmacologically relevant molecules due to their rich biological activities and chemical scaffolds. Type II-PKS manufactured polyketides share similar polycyclic aromatic backbones leaving their diversity to stem from various chemical additions and alterations facilitated by post-PKS tailoring enzymes. Evidence suggests that post-PKS tailoring enzymes form complexes in order to facilitate the highly orchestrated process of biosynthesis. Thus, protein-protein interactions between these enzymes must play crucial roles in their structures and functions. Despite the importance of these interactions little has been done to study them. In …

Understanding The Chemical Gymnastics Of Enzyme-Catalyzed 1’-1 And 1’-3 Triterpene Linkages, Stephen A. Bell

Theses and Dissertations--Plant and Soil Sciences

Squalene synthase (SS) is an essential enzyme in eukaryotic systems responsible for an important branch point in isoprenoid metabolism that leads to sterol formation. The mechanistic complexity of SS has made it a difficult enzyme to study. The green alga Botryococcus braunii race B possesses several squalene synthase-like (SSL) enzymes that afford a unique opportunity to study the complex mechanism of triterpene biosynthesis. SSL-1 catalyzes presqualene diphosphate (PSPP) formation, which can either be converted to squalene by SSL-2 or botryococcene by SSL-3. A rationally designed mutant study of B. braunii squalene synthase (BbSS) and SSL-3 was conducted to understand structure-function …

Neuropilin In The Vascular System: Mechanistic Basis Of Angiogenesis, Hou-Fu Guo

Theses and Dissertations--Molecular and Cellular Biochemistry

The vascular system is critical for maintaining homeostasis in all vertebrates. Structural studies of Neuropilin (Nrp), an essential angiogenic receptor, have defined its role in regulating angiogenesis, the formation of new vessels from the existing vasculature. Utilizing biochemical and biophysical tools we describe the ability of Nrp to function as a co-receptor for the VEGFR receptor tyrosine kinase. Two families of Nrp-1 ligands, Vascular Endothelial Growth Factor A (VEGF-A) and Semaphorin3F (Sema3F), physically compete for binding to the Nrp-1 b1 domain, and have opposite roles. VEGF-A is a potent pro-angiogenic cytokine while Sema3F is an angiogenesis inhibitor. Using coupled structural …

Molecular Mechanisms Of Neuropilin-Ligand Binding, Matthew W. Parker

Theses and Dissertations--Molecular and Cellular Biochemistry

Neuropilin (Nrp) is an essential cell surface receptor with dual functionality in the cardiovascular and nervous systems. The first identified Nrp-ligand family was the Semaphorin-3 (Sema3) family of axon repulsion molecules. Subsequently, Nrp was found to serve as a receptor for the vascular endothelial growth factor (VEGF) family of pro-angiogenic cytokines. In addition to its physiological role, VEGF signaling via Nrp directly contributes to cancer stemness, growth, and metastasis. Thus, the Nrp/VEGF signaling axis is a promising anti-cancer therapeutic target. Interestingly, it has recently been shown that Sema3 and VEGF are functionally opposed to one another, with Sema3 possessing potent …

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 …

Stability Studies Of Membrane Proteins, Cui Ye

Theses and Dissertations--Chemistry

The World Health Organization has identified antimicrobial resistance as one of the top three threats to human health. Gram-negative bacteria such as Escherichia coli are intrinsically more resistant to antimicrobials. There are very few drugs either on the market or in the pharmaceutical pipeline targeting Gram-negative pathogens. Two mechanisms, the protection of the outer membrane and the active efflux by the multidrug transporters, play important roles in conferring multidrug resistance to Gram-negative bacteria. My work focuses on two main directions, each aligning with one of the known multidrug resistance mechanisms.

The first direction of my research is in the area …