Life Sciences Commons^™

Enzymatic Analysis Of Yeast Cell Wall-Resident Gapdh And Its Secretion, Michael J. Cohen, Brianne Philippe, Peter N. Lipke

Publications and Research

In yeast, many proteins are found in both the cytoplasmic and extracellu- lar compartments, and consequently it can be difficult to distinguish nonconventional secretion from cellular leakage. Therefore, we monitored the extracellular glyceralde- hyde-3-phosphate dehydrogenase (GAPDH) activity of intact cells as a specific marker for nonconventional secretion. Extracellular GAPDH activity was proportional to the number of cells assayed, increased with incubation time, and was dependent on added substrates. Preincubation of intact cells with 100mM dithiothreitol increased the reac- tion rate, consistent with increased access of the enzyme after reduction of cell wall di- sulfide cross-links. Such treatment did not increase …

Unconventional Constituents And Shared Molecular Architecture Of The Melanized Cell Wall Of C. Neoformans And Spore Wall Of S. Cerevisiae, Christine Chrissian, Coney Pei-Chin Lin, Emma Camacho, Arturo Casadevall, Aaron M. Neiman, Ruth E. Stark

Publications and Research

The fungal cell wall serves as the interface between the cell and the environment. Fungal cell walls are composed largely of polysaccharides, primarily glucans and chitin, though in many fungi stress-resistant cell types elaborate additional cell wall structures. Here, we use solid-state nuclear magnetic resonance spectroscopy to compare the architecture of cell wall fractions isolated from Saccharomyces cerevisiae spores and Cryptococcus neoformans melanized cells. The specialized cell walls of these two divergent fungi are highly similar in composition. Both use chitosan, the deacetylated derivative of chitin, as a scaffold on which a polyaromatic polymer, dityrosine and melanin, respectively, is assembled. …

Two And Three-Dimensional Radiographic Imaging Of Contrast Agents In Heterogeneous Live Cell Media To Understand Contrast-Induced Toxicity, Fahaneda Hassan, Aldona Gjoni, Subhendra Sarkar

Publications and Research

Radiographic imaging was done using low and high energy radiography equipment. The test hypothesis that macromolecular aggregation changes sample noise in imaging samples for optical imaging methods. Inorganic complexes scatter radiation at the molecular level and may increase the sample noise locally. At high and low photon energies in various x-ray machines, sample and background noise were gathered and compared with those from mammography systems from mammography researchers. The samples with high macromolecular aggregates were prepared using various animal cell compositions and imaged under different conditions that produced different macromolecular dynamics within the samples and thus different image-based sample noise. …

3,7-Dihydroxytropolones Inhibit Initiation Of Hepatitis B Virus Minus-Strand Dna Synthesis, Ellen Bak, Jennifer T. Miller, Andrea Noronha, John Tavis, Emilio Gallicchio, Ryan P. Murelli, Stuart F. J. Le Grice

Publications and Research

Initiation of protein-primed (-) strand DNA synthesis in hepatitis B virus (HBV) requires interaction of the viral reverse transcriptase with epsilon (ε), a cis-acting regulatory signal located at the 5’ terminus of pre-genomic RNA (pgRNA), and several host-encoded chaperone proteins. Binding of the viral polymerase (P protein) to ε is necessary for pgRNA encapsidation and synthesis of a short primer covalently attached to its terminal domain. Although we identified small molecules that recognize HBV ε RNA, these failed to inhibit protein-primed DNA synthesis. However, since initiation of HBV (-) strand DNA synthesis occurs within a complex of viral and host …

Retrieving Functional Pathways Of Biomolecules From Single-Particle Snapshots, Ali Dashti, Ghoncheh Mashayekhi, Mrinal Shekhar, Danya Ben Hail, Salah Salah, Peter Schwander, Amedee Des Georges, Abhishek Singharoy, Joachim Frank, Abbas Ourmazd

Publications and Research

A primary reason for the intense interest in structural biology is the fact that knowledge of structure can elucidate macromolecular functions in living organisms. Sustained effort has resulted in an impressive arsenal of tools for determining the static structures. But under physiological conditions, macromolecules undergo continuous conformational changes, a subset of which are functionally important. Techniques for capturing the continuous conformational changes underlying function are essential for further progress. Here, we present chemically-detailed conformational movies of biological function, extracted data-analytically from experimental single-particle cryo-electron microscopy (cryo-EM) snapshots of ryanodine receptor type 1 (RyR1), a calcium-activated calcium channel engaged in the …

A Paradigm For Peptide Hormone-Gpcr Analyses, Fred Naider, Jeffrey M. Becker

Publications and Research

Work from our laboratories over the last 35 years that has focused on Ste2p, a G protein-coupled receptor (GPCR), and its tridecapeptide ligand α-factor is reviewed. Our work utilized the yeast Saccharomyces cerevisiae as a model system for understanding peptide-GPCR interactions. It explored the structure and function of synthetic α-factor analogs and biosynthetic receptor domains, as well as designed mutations of Ste2p. The results and conclusions are described using the nuclear magnetic resonance interrogation of synthetic Ste2p transmembrane domains (TMs), the fluorescence interrogation of agonist and antagonist binding, the biochemical crosslinking of peptide analogs to Ste2p, and the phenotypes of …

Machine Learning Applications For Drug Repurposing, Hansaim Lim

Dissertations, Theses, and Capstone Projects

The cost of bringing a drug to market is astounding and the failure rate is intimidating. Drug discovery has been of limited success under the conventional reductionist model of one-drug-one-gene-one-disease paradigm, where a single disease-associated gene is identified and a molecular binder to the specific target is subsequently designed. Under the simplistic paradigm of drug discovery, a drug molecule is assumed to interact only with the intended on-target. However, small molecular drugs often interact with multiple targets, and those off-target interactions are not considered under the conventional paradigm. As a result, drug-induced side effects and adverse reactions are often neglected …

Small Molecule Synthetic Carbohydrate Receptors, Marcelo F. Bravo Carranco

Dissertations, Theses, and Capstone Projects

Carbohydrate – receptor interactions are often involved in the attachment of viruses to host cells, and this docking is a necessary step in the virus life cycle that precedes infection and, ultimately, replication. Despite the conserved structures of the glycans involved in docking, they are still considered “undruggable”, meaning these glycans are beyond the scope of conventional pharmacological strategies. Recent advances in the development of synthetic carbohydrate receptors (SCRs) – small molecules that bind carbohydrates – could bring carbohydrate-receptor interactions within the purview of druggable targets. Here we discuss the role of carbohydrate-receptor interactions in viral infection, the evolution of …

Pointing The Zinc Finger On Protein Folding: Energetic Investigation Into The Role Of The Metal-Ion In The Metal-Induced Protein Folding Of Zinc Finger Motifs, Inna Bakman-Sanchez

Dissertations, Theses, and Capstone Projects

Interactions between inorganic metal-ion cofactors and organic protein scaffolds are important for the proper structure and function of metalloproteins. Zinc finger proteins (ZFPs) are an example of proteins with such crucial metal-protein interactions. Incorporation of the Zn(II)-ion into ZFPs allows for their correct folding into structures that can carry out vital biological functions which include gene expression and tumor suppression. In addition, engineered ZFPs have shown to be promising genetic therapeutics in the clinic. And yet, there is still a gap in a quantitative understanding of the energetic contribution of the metal-protein interactions towards the structure and function of these …

Performance Of A Dna And Protein Co-Extraction With Trypsin In Comparison To Two Proteinase K Based Dna Extraction Methods, Dinura A. Gunatilake

Student Theses

Effective DNA extraction methods are important for forensic applications. The main goal of this experiment was to determine if a newly developed trypsin based protein/DNA co-extraction method applied to contact traces would yield comparable results to a commercial Proteinase K method (QIAamp DNA Investigator Kit) and a Chelex extraction method with Tween 20 used in forensic laboratories. This was tested on 20 sets of sebaceous fingerprints on glass slides.

The results of this study demonstrate the trypsin co-extraction method yielded the highest amount of DNA. In the first comparison, the mean total DNA yields for the trypsin-co extraction method and …

Ionophoric Polyphenols Are Permeable To The Blood Brain Barrier, Interact With Human Serum Albumin And Calf Thymus Dna, And Inhibit Ache Enzymatic Activity, Alberto Martinez, Mai Zahran, Miguel Gomez, Johnny Guevara, Rosemary Pichardo-Bueno, Junaid Asim, Gabriel Ortiz, Yaa Andoh, Sinji Shibutani, Baljit Kaur

Publications and Research

Alzheimer’s disease (AD) is the most common form of dementia that affects more than 40 million people around the world. The incidence is expected to rapidly increase due to the lack of any effective treatment. In previous work we synthesized a family of five ionophoric polyphenols (compounds 1–5) that targeted important aspects related to AD, such as the toxic aggregation of amyloid-β peptides, the production of reactive oxygen species, or the excessive presence of Cu²⁺ ions. Here, in order to gain insights into their potential therapeutic value, we have tested the ability of compounds 1– …

Analysis Of Olfactory Mrna Cap Modifications Using Rnaseh And Lc-Ms, Ilinca M. Giosan

Theses and Dissertations

In the olfactory system, olfactory sensory neurons (OSNs) express odorant receptors (ORs) in a singular fashion through unknown mechanisms. Published data supports the notion that singularity is achieved, in part, through a modification the mRNA strand, perhaps in its 5’cap region. This theoretical study aims to test this 5’cap hypothesis.

Snow-Albedo Feedback In Northern Alaska: How Vegetation Influences Snowmelt, Lucas C. Reckhaus

Theses and Dissertations

This paper investigates how the snow-albedo feedback mechanism of the arctic is changing in response to rising climate temperatures. Specifically, the interplay of vegetation and snowmelt, and how these two variables can be correlated. This has the potential to refine climate modelling of the spring transition season. Research was conducted at the ecoregion scale in northern Alaska from 2000 to 2020. Each ecoregion is defined by distinct topographic and ecological conditions, allowing for meaningful contrast between the patterns of spring albedo transition across surface conditions and vegetation types. The five most northerly ecoregions of Alaska are chosen as they encompass …

Evolutionary Algorithms Converge Towards Evolved Biological Photonic Structures, Mamadou Aliou Barry, Vincent Berthier, Bobo D. Wilts, Marie-Claire Cambourieux, Pauline Bennet, Rémi Pollès, Olivier Teytaud, Emmanuel Centeno, Nicolas Biais, Antoine Moreau

Publications and Research

Nature features a plethora of extraordinary photonic architectures that have been optimized through natural evolution in order to more efciently refect, absorb or scatter light. While numerical optimization is increasingly and successfully used in photonics, it has yet to replicate any of these complex naturally occurring structures. Using evolutionary algorithms inspired by natural evolution and performing particular optimizations (maximize refection for a given wavelength, for a broad range of wavelength or maximize the scattering of light), we have retrieved the most stereotypical natural photonic structures. Whether those structures are Bragg mirrors, chirped dielectric mirrors or the gratings on top of …

Circuits With Broken Fibration Symmetries Perform Core Logic Computations In Biological Networks, Ian Leifer, Flaviano Morone, Saulo D. S. Reis, José S. Andrade Jr., Mariano Sigman, Hernán A. Makse

Publications and Research

We show that logic computational circuits in gene regulatory networks arise from a fibration symmetry breaking in the network structure. From this idea we implement a constructive procedure that reveals a hierarchy of genetic circuits, ubiquitous across species, that are surprising analogues to the emblematic circuits of solid-state electronics: starting from the transistor and progressing to ring oscillators, current-mirror circuits to toggle switches and flip-flops. These canonical variants serve fundamental operations of synchronization and clocks (in their symmetric states) and memory storage (in their broken symmetry states). These conclusions introduce a theoretically principled strategy to search for computational building blocks …

Dictyostelium Discoideum Protein Kinase C-Orthologue Pkca Regulates The Actin Cytoskeleton Through Interaction With Phospholipase D And P21-Activated Kinase, Sean Singh

Dissertations, Theses, and Capstone Projects

Proper regulation of the actin cytoskeleton is crucial to many cellular processes. Many of these processes are regulated by extracellular signaling cues, which direct changes in the actin cytoskeleton, resulting in changes to cellular morphology, and directed motility. The social amoeba, Dictyostelium discoideum, is used as a simple model system to study the translation of extracellular signals to the actin cytoskeleton. When starved, these unicellular amoebae undergo a multicellular developmental process characterized by a tightly regulated sequence of signaling events. This results in chemotaxis and formation of a multicellular aggregate, and ultimately cell differentiation and the formation of a fruiting …

Probing The Limits Of Singular Gene Expression Through The Activity Of High Representation Odorant Receptor Transgenes, Eugene Lempert

Dissertations, Theses, and Capstone Projects

Singular gene expression is a common phenomenon in biology, making its appearance in immunoglobulin selection, protocadherin expression, X chromosome-inactivation, random monoallelic expression, and olfactory receptor choice. Singularity involves an activation and a feedback step. The mechanisms of singular gene choice have some capacity to integrate additional member genes while still maintaining singularity, but will activate an additional member if an earlier choice was incapable of triggering the feedback step. Odorant Receptor (OR) genes are substantially divergent from each other in terms of coding sequence, promoter structure, and genomic locus, all of which plays a role in how many Olfactory Sensory …

Development Of Ligand Guided Selection (Ligs) To Identify Specific Dna Aptamers Against Cell Surface Proteins, Hasan Ekrem Zumrut

Dissertations, Theses, and Capstone Projects

Oligonucleotide aptamers (nucleic acid-based affinity reagents) are an emerging class of synthetic molecules that display high affinity and specificity towards their targets. Aptamer molecules for a target of interest are obtained using a combinatorial chemistry-based method termed systematic evolution of ligands by exponential enrichment (SELEX). SELEX is an in vitro selection process in which a random oligonucleotide library is subjected to repeated cycles of target incubation, separation, and amplification until target-specific evolved sequences become prevalent in the library. Typically, SELEX is used against target molecules such as small molecules and proteins, in their purified state. However, aptamers selected against purified …

Dna Damage Recognition And Uvrb Loading By Uvra Within The Nucleotide Excision Repair Pathway, Silas Hartley

Dissertations, Theses, and Capstone Projects

Maintaining the cellular genome is paramount to survival by any organism. A mutated genome can have detrimental effects on different cellular processes, especially replication and transcription. Cells maintain their genome using different deoxyribonucleic acid (DNA) repair pathways. The nucleotide excision repair (NER) pathway has a unique capability of repairing the genome from several different mutations, deletions, and adducts. In bacteria, the NER pathway accomplishes repair through four important steps: damage recognition by UvrA, damage verification by UvrB, DNA incision by UvrC, and repair synthesis using various cellular machinery.

UvrA forms a head-to-head dimer (UvrA₂) with two ATPase sites …

Structural And Dynamic Features Of A Transiently Assembled Complex Between A Bacterial Tyrosine Kinase And Its Cognate Phosphatase, Imane Djemil

Dissertations, Theses, and Capstone Projects

Bacterial tyrosine kinases (BY-kinases) and their cognate Low Molecular Weight Tyrosine Phosphatases (LMW-PTP) work synergistically to regulate diverse physiological processes in both Gram-negative and Gram-positive bacteria. Of these processes, the most widely recognized role of the kinase/phosphatase pair is the biosynthesis and transport of surface polysaccharides. A process that is key in protecting bacterial cell from a variety of environmental stresses through biofilm formation, and the generation of virulence-determining capsules in pathogenic strains. BY-kinases contain a C-terminal tyrosine rich cluster (Y-cluster) located on the catalytic domain that undergoes auto-phosphorylation and is subsequently dephosphorylated by the cognate LMW-PTPs. This phosphorylation/dephosphorylation cycle …

Proton Pumping Mechanism In Cytochrome C Oxidase, Xiuhong Cai

Dissertations, Theses, and Capstone Projects

Cytochrome c Oxidase (CcO), is the terminal electron acceptor in the membrane bound aerobic respiratory chain. It reduces O₂ to water. The energy released by this reaction is stored by pumping protons from the high pH, N-side of the membrane to the low pH, P-side. The generated proton gradient provides the motive force for synthesis of ATP by the ATP synthase.

Building a proton gradient across the membrane requires that proton transport must occur along controllable proton pathways to prevent proton leakage to the N-side. It has been suggested that CcO function requires proton transfer channels in both the …

Discrimination Of Monozygotic Twins Using Dna Methylation Levels Of One Cpg Site At Chromosome 3, Dino O. Robinson

Student Theses

Conventional STR typing, commonly used in forensics for human identification, poses a problem in criminal cases and paternity disputes involving monozygotic (MZ) twins because they share identical DNA sequences. To date, no routine method is available in forensics to differentiate between individuals of MZ pairs. Recently, epigenetic methods measuring differential DNA methylation patterns have been applied to MZ twin differentiation. In this study, we investigated the potential to identify MZ twins using a previously identified DNA methylation site in chromosome 3, cg18562578, in a sample of 129 MZ and 37 dizygotic (DZ) twin pairs. We used bisulfite converted saliva DNA …

Fibration Symmetries Uncover The Building Blocks Of Biological Networks, Flaviano Morone, Ian Leifer, Hernán A. Makse

Publications and Research

A major ambition of systems science is to uncover the building blocks of any biological network to decipher how cellular function emerges from their interactions. Here, we introduce a graph representation of the information flow in these networks as a set of input trees, one for each node, which contains all pathways along which information can be transmitted in the network. In this representation, we find remarkable symmetries in the input trees that deconstruct the network into functional building blocks called fibers. Nodes in a fiber have isomorphic input trees and thus process equivalent dynamics and synchronize their activity. Each …

C-Di-Gmp Modulates Type Iv Msha Pilus Retraction And Surface Attachment In Vibrio Cholerae, Kyle A. Floyd, Calvin K. Lee, Wujing Xian, Mahmoud Nametalla, Aneesa Valentine, Benjamin Crair, Shiwei Zhu, Hannah Q. Hughes, Jennifer L. Chlebek, Daniel C. Wu, Jin Hwan Park, Ali M. Farhat, Charles J. Lomba, Courtney K. Ellison, Yves V. Brun, Javier Campos-Gomez, Ankur B. Dalia, Jun Liu, Nicolas Biais, Gerard C. L. Wong, Fitnat H. Yildiz

Publications and Research

Biofilm formation by Vibrio cholerae facilitates environmental persistence, and hyperinfectivity within the host. Biofilm formation is regulated by 3’,5’-cyclic diguanylate (c-di-GMP) and requires production of the type IV mannose-sensitive hemagglutinin (MSHA) pilus. Here, we show that the MSHA pilus is a dynamic extendable and retractable system, and its activity is directly controlled by c-di-GMP. The interaction between c-di-GMP and the ATPase MshE promotes pilus extension, whereas low levels of c-di-GMP correlate with enhanced retrac- tion. Loss of retraction facilitated by the ATPase PilT increases near-surface roaming motility, and impairs initial surface attachment. However, prolonged retraction upon surface attach- ment results …

Metabolic Reprogramming By C-Met Inhibition As A Targetable Vulnerability In Glioblastoma, Trang Thi Thu Nguyen, Enyuan Shang, Georg Karpel-Massler, Markus D. Siegelin

Publications and Research

The elucidation of better treatments for solid tumors and especially malignant glial tumors is a priority. Better understanding of the molecular underpinnings of treatment response and resistance are critical determinants in the success for this endeavor. Recently, a battery of novel tools have surfaced that allow to interrogate tumor cell metabolism to more precise extent than this was possible in the earlier days. At the forefront of these developments are the extracellular flux and carbon tracing analyses. Through utilization of these techniques our group made the recent observation that acute and chronic c-MET inhibition drives fatty acid oxidation that in …

Through The Back Door: Proteins Escape Cells Without Conventional Permission, Michael J. Cohen

Dissertations, Theses, and Capstone Projects

Proteins secreted to the extracellular environment play a fundamental role as signals, in metabolism, and a variety of other processes. The process of secretion through the endoplasmic reticulum and Golgi to the plasma membrane is well documented, and all cargo in this pathway contains a signal peptide. However, a variety of proteins secreted from eukaryotes lack a signal peptide and are called unconventionally secreted proteins. Here we discuss known mechanisms of unconventional protein secretion, as well as model proteins which follow characterized pathways. Additionally, we summarize the roles various unconventionally secreted proteins play outside of cells and suggest criteria for …

Parp1-Targeted Radiotherapies, Stephen Jannetti

Dissertations, Theses, and Capstone Projects

Poly-ADP-ribosylation reactions were first reported by Chambon in 1963 as enzymatic activity that increases incorporation of ATP in the presence of nicotinamide mononucleotide. In the decades since that publication, Poly(ADP-ribose)polymerase 1 (PARP1) and the PARP family enzymes have been widely studied. PARP enzymes are currently known to play various roles in mammals, including anti-aging processes, interactions with Breast Cancer Suppressor Protein-1 (BRCA1), and DNA damage repair. A significant focus of PARP1 research has been elucidating its role in DNA damage repair. PARP1 is recruited to repair single strand DNA (ssDNA) breaks, which can become double stranded DNA (dsDNA) breaks if …

Advanced Computational Methodologies To Study Binding Free Energies Of Biomolecular Complexes, Rajat Kumar Pal

Dissertations, Theses, and Capstone Projects

Molecular recognition is the basis of biological mechanisms and is a key element to consider while formulating effective and safe drugs. Pharmaceutical drugs are designed so as to bind a target protein even at very low concentrations to alter the diseased conditions without interfering with normal biological processes. In a rational drug design process, this is achieved by acquiring information about the chemical structure and the physical and chemical properties of the target protein receptor to gain insights on how changing the chemical composition of the substrate drug could affect the protein-drug interaction and binding affinities. Computational models are used …

Hur Ubiquitination By Brca1/Bard1 And Its Role In Controlling Gene Expression During Dna Damage Response, Gamage M. Aruggoda

Dissertations, Theses, and Capstone Projects

Despite our understanding of the biochemistry of the BRCA1/BARD1 E3 ligase, we know very little of the mechanism by which its cellular substrates, how they are chosen, how its E3 Ub ligase activity is regulated, which are the cofactors involved in this regulation, and how the substrates are modified during DDR. In this dissertation, I further evaluate BRCA1/BARD1-mediated E3 ligase activity and how CstF-50 and p97 regulate this reaction working as cofactors. My data show that BRCA1/BARD1 is an E3 ligase that ubiquitinates the RNA binding protein Human antigen R(HuR).

HuR is abundant in the nucleus and is transported to …

Mutational Analysis And Domain Characterization Of The Apolipoprotein L-1 Ion Channel, Charles M. Schaub

Dissertations, Theses, and Capstone Projects

The human innate immunity factor Apolipoprotein L-1 (APOL1) protects against Trypanosoma brucei brucei infection. Recent studies have shown recombinant APOL1 (rAPOL1) inserts into planar lipid bilayers at an acidic pH 5.6 and forms a cation-selective channel, which opens upon subsequent neutralization, pH 7.2. This corresponds with the pH changes APOL1 would encounter during endosome recycling, suggesting that APOL1 forms a pH-gated ion channel in the plasma membrane of the parasite, leading to uncontrolled ion flux and osmotic imbalance. However, structural and domain characteristics of the APOL1 channel are poorly understood, despite potential similarities to diphtheria and colicin toxins. Utilizing E. …