Digital Commons Network^™

Identifying Functional Components Of The Endoplasmic Reticulum Quality Control And Degradation Factor Edem1, Lydia Lamriben

Doctoral Dissertations

The ER Degradation-Enhancing Mannosidase-Like protein 1 (EDEM1) is a critical endoplasmic reticulum (ER) quality control factor involved in identifying and directing non-native proteins to the ER-associated protein degradation (ERAD) pathway. However, its recognition and binding properties have remained enigmatic since its discovery. Here we provide evidence for an additional redox-sensitive interaction between EDEM1 and Z/NHK that requires the presence of the single Cys on the α-1 antitrypsin ERAD clients. Moreover, this Cys-dependent interaction is necessary when the proteins are isolated under stringent detergent conditions, ones in which only strong covalent interactions can be sustained. This interaction is inherent to the …

Structural Studies Of Acid Alpha Glucosidase And Pompe Disease, Derrick Deming

Doctoral Dissertations

Acid α-glucosidase (GAA) is required for the degradation of lysosomal glycogen. Pompe disease is an autosomal recessive disorder caused by reduced GAA activity, resulting in the accumulation of glycogen within lysosomes. The most severe form of the disease is characterized by a progressive deterioration of cardiac and skeletal muscle leading to death before two years of age. An intense interest from both the academic and pharmaceutical communities led us to determine the crystal structure of GAA. The structure provides insight into Pompe disease by examining how over 200 disease-associated point mutations perturb GAA function. To aid in the development of …

Applications Of Drosophila Melanogaster In Food Science Research, Phoebe Beverly Chen

Doctoral Dissertations

Drosophila melanogaster is a versatile model organism that provides several unique features, such as highly conserved disease pathways with humans as well as availability of environmental and genetic manipulations. Meanwhile, there is increasing interest in the potential role of bioactive food components, epigallocatechin gallate (EGCG) and conjugated linoleic acid (CLA), in metabolic research. However, there is limited knowledge on the sex-dependent effects of EGCG and CLA on energy metabolism. In this study, Drosophila melanogaster was used to investigate the sex-dependent effects of EGCG and CLA with respect to energy metabolism, including body fat, locomotion, and their key metabolic regulators. We …

Role Of The Facial Triad In Factor Inhibiting Hif (Fih): Ligand Binding, Substrate Selectivity, And Coupling, Vanessa Chaplin

Doctoral Dissertations

Alpha-ketoglutarate (αKG) dependent oxygenases comprise a large superfamily of enzymes that activate O₂ for varied reactions. While most of these enzymes contain a non-heme Fe bound by a His₂Asp facial triad, a small number of αKG-dependent halogenases require only the two His ligands to bind Fe and activate O₂. The enzyme “factor inhibiting HIF” (FIH) contains a His₂Asp facial triad and selectively hydroxylates polypeptides, however removal of the Asp ligand in the D201G variant leads to a highly active enzyme, seemingly without a complete facial triad. Herein, we report on the formation of …

The Interplay Between Polarity Regulators, Calcium, And The Actin Cytoskeleton During Tip Growth, Carlisle Bascom Jr

Doctoral Dissertations

Plant cell growth is a meticulously regulated process whereby the cell wall is selectively loosened to allow for turgor-pressure driven expansion. The rate of expansion must equal delivery of new material, or the cell will lyse. In many plant cells, this process happens diffusely around the cell. However, a number of plant cells have anisotropic shapes that require exquisite spatial control of secretion. One simple example of anisotropic patterning is tip growth; highly polarized cell expansion utilized by pollen tubes, root hairs, and moss protonemata. Investigating the role various molecules have in tip growth sheds light on how plant cells …

Feronia-Related Receptor Kinase 7 And Feronia And Their Role In Receiving And Transducing Signals, David Vyshedsky

Masters Theses

Receptor kinases (RKs) are transmembrane proteins that have been shown to regulate an array of important processes in A. thaliana, including polar cell growth, plant reproduction, and many other plant growth processes. In this thesis, I examine RECEPTOR KINASE 7 (RK7) and FERONIA (FER), two closely related transmembrane RKs, and their effects on plant reproduction. The RK7 gene when knocked out (rk7) in conjunction with FER resulted in delayed plant growth, decreased seed yield, and a lower percentage of the seeds germinating as compared to the single FER knockout. Transgenic plants with GUS reporter driven by RK7 promoter …

Exploring The Influence Of Pkc-Theta Phosphorylation On Notch1 Activation And T Helper Cell Differentiation, Grace Trombley

Masters Theses

The T cell-specific kinase, Protein Kinase C theta (PKCq) is essential to T cell activation and differentiation. PKCq integrates T cell receptor (TCR) and CD28 signaling, and ultimately activates transcription factors necessary for full T cell activation, proliferation, survival, and differentiation into T helper (Th) subsets. Th1, Th2, Th17 and Treg cells compose the four major lineages of T helper cells, differentiated from CD4 T cells, and each have different requirements for PKCq.

PKCq, itself, is regulated through phosphorylation of specific resides, including tyrosine (Y)90 and threonine (T)538. Following T cell stimulation, PKCq is phosphorylated on Y90 by the kinase, …

Investigating The Role Of Rna-Binding Protein 5 In The Life Cycle Differentiation Of Trypanosoma Brucei, David Anaguano Pillajo

Masters Theses

Trypanosomatid parasites such as Trypanosoma brucei have unusual mechanisms of gene expression including polycistronic transcription, mitochondrial RNA editing and trans-splicing. Additionally, these protists rely mainly on post-transcriptional regulation where RNA-binding proteins (RBP) have shown to play a major role. RBP6 and RBP10 are two examples of RBPs that play crucial roles in procyclic and bloodstream form parasites differentiation respectively, by post-transcriptional regulation. Over-expression of RBP6 is enough to promote differentiation into metacyclic trypomastigotes that are infective to mice. However, continuous expression is required, and this pattern does not reflect the natural expression in the tsetse fly or the influence of …

Characterization Of She1 Spindle Role Using Ceullular, Biochemical, And Biophysical Methods, Yili Zhu

Doctoral Dissertations

During development, metaphase spindles undergo large movement and/or rotation to determine the cell division axis. While it has been shown that spindle translocation is achieved by astral microtubules pulling and/or pushing the cortex, how metaphase spindle stability is maintained during translocation remains not fully understood. In budding yeast, our lab has previously proposed a model for spindle orientation wherein the mitotic spindle protein She1 promotes spindle translocation across the bud neck by polarizing cortical dynein pulling activity on the astral microtubules. Intriguingly, She1 exhibits dominant spindle localization throughout the cell cycle. However, whether She1 has any additional role on the …

Studies On The P. Aeruginosa T3s Translocon Assembly: Interaction Of Popd With Membranes, Yuzhou Tang

Doctoral Dissertations

Type III secretion (T3S) system is deployed by a wide range of pathogens to manipulate host cell response and establish infection. The T3S system is a syringe-like apparatus that spans across the double membrane of bacteria, protruding 50nm-80nm into the extracellular space and connecting with target cell membrane. In Pseudomonas aeruginosa, the proteins PopB and PopD are secreted and found associated with the target eukaryotic cell membrane. These two proteins are believed to form a transmembrane complex or translocon to allow effector protein translocation. Despite its key role in pathogenesis, the assembly mechanism and structure of this critical transmembrane …

Co-Engineering Proteins And Nanoparticles For Fundamental Study And Delivery Applications, Moumita Ray

Doctoral Dissertations

Engineered nanoparticles provide a powerful scaffold for interfacing with proteins. The nanoparticle surface can be tailored to present recognition elements, providing surface complementarity to interact with protein surfaces. In this thesis, I have explored both the fundamental and the applied aspects of this interaction. On the fundamental side, I have co-engineered the nanoparticles and the proteins to generate robust dyads with strong binding affinity even at high salt concentration. Fluorescence titrations and docking studies were carried out to quantify the binding properties of the nanoparticles and proteins. Those studies revealed the prospect of tuning the affinity between the nanoparticles and …

Extrinsic And Intrinsic Factors In Liver Development, Amrita Palaria

Doctoral Dissertations

Liver is the largest internal organ of the human body. It performs a multitude of functions. Therefore, it is provided with a huge regenerative capacity however, because of the same reason it is also prone to various diseases. Hence, it is essential to understand liver development in order to understand liver regeneration and liver diseases to provide better therapeutic targets and solutions. Liver development is orchestrated by a variety of intrinsic and extrinsic factors. The major focus of this dissertation thesis is to elucidate the role of BMP signals and YY1/VEGFA regulated signals in liver development. Liver organogenesis initiates with …

Hydrogen Exchange Identifies Protein Interfaces And Signaling-Related Changes In Functional Chemoreceptor Arrays, Xuni Li

Doctoral Dissertations

Chemotaxis is an ideal system for studying membrane protein signal transduction. Chemoreceptors are transmembrane proteins that sense chemicals in the environment and use this information to control a phosphorylation cascade that enables the cell to swim towards favorable environments. The receptors form a ternary complex with a histidine kinase, CheA, and an adaptor protein, CheW. These complexes assemble into membrane-bound hexagonal arrays that transmit the signal that controls CheA. It is widely accepted that ligand binding to the receptor causes a 2Å piston motion of a helix that extends through the periplasmic and transmembrane domains. But it is unclear how …

Examining Shsp-Substrate Capture And Chaperone Network Coordination Through Cross-Linking, Keith Ballard

Doctoral Dissertations

Small heat shock proteins (sHSPs) and related α-crystallins are virtually ubiquitous, ATP-independent molecular chaperones linked to protein misfolding diseases. They comprise a conserved core α-crystallin domain (ACD) flanked by an evolutionarily variable N-terminal domain (NTD) and semi-conserved C-terminal extension/domain (CTD). They are capable of binding up to an equal mass of unfolding protein, forming large, heterogeneous sHSP-substrate complexes that coordinate with ATP-dependent chaperones for refolding. To derive common features of sHSP-substrate recognition, I compared the chaperone activity and specific sHSP-substrate interaction sites for three different sHSPs from Arabidopsis (At17.6B), pea (Ps18.1) and wheat (Ta16.9), for which the atomic solution-state structures …

In Vitro S-Glutathionylation Of S-Nitrosoglutathione Reductase From Arabidopsis Thaliana And Phenotype Determination Of Sensitive To Formaldehyde 1 Knockout Strains Of Saccharomyces Cerevisiae, Ian Truebridge

Masters Theses

Cells are constantly exposed to different stresses – one being redox stress, which is induced by metal, reactive oxygen species and reactive nitrogen species. S-nitrosoglutathione reductase (GSNOR) helps modulate redox stress by two different mechanisms – either by reducing S-nitrosoglutathione (GSNO) to oxidized glutathione (GSSG) or by oxidizing hydroxymethyl glutathione (HMGSH), a biproduct of glutathione and formaldehyde, to formic acid. GSNO has the potential to posttranslational modify proteins in two different manners, either by S-nitrosation or by S-glutathionylation. Interestingly, GSNOR can be modified by its substrate GSNO, either by S-nitrosation, which has previously been reported, or, as discussed in this …

Observing The Molecular Basis Of Thin Filament Activation With A Three Bead Laser Trap Assay, Thomas Longyear

Doctoral Dissertations

Muscle contracts after calcium (Ca++) is released into the muscle cell, resulting from a cascade of events which result in myosin, the molecular motor of muscle, to produce force and motion. Myosin cyclically binds to a regulated thin filament, using the chemical energy of ATP to produce force and motion. Perturbations in muscle, such as a build-up of metabolic by-products or point mutations in key contractile proteins, can inhibit these functions in both skeletal and cardiac muscle either acutely or chronically. Despite the many years we have studied skeletal and cardiac muscle, we still do not have a clear picture …

The Molecular Basis Of Caspase-9 Inactivation By Pka And C-Abl Kinases, Banyuhay Paningbatan Serrano

Doctoral Dissertations

Caspases are the cysteine proteases that facilitate the fundamental pathway of programmed cell death or apoptosis. The activation and function of these powerful enzymes are tightly regulated to ensure the faithful execution of apoptosis and prevent untimely cell death. Many deadly human diseases such as cancer, neurodegeneration and autoimmune disorders have been associated with defective activation and faulty regulation of caspases. As such, caspases are considered as attractive drug targets, which when properly controlled, can lead to effective therapeutics for apoptosis-related diseases. Thus, comprehensive investigations of the structure, function and regulation of caspases are necessary to understand the complex mechanisms …

Clpxp Functions In Caulobacter As A Universal And Species-Specific Protease, Robert Vass

Doctoral Dissertations

Proteolysis shapes many aspects of cellular survival, including protein quality control and cellular signaling. Powered proteolysis couples ATP hydrolysis with a degradation force that actively probes and interrogates the protein population. ClpXP, exemplifies a conserved two-part protease system charged with powered proteolysis. This protease exists as a regulatory element (ClpX), and a compartmentalized, self-contained peptidase element (ClpP). In Caulobacter crescentus, ClpXP degradation plays a crucial role maintaining proteins that exhibit proper activity, and also triggers the start of cellular differentiation. Substrate elimination requires shared aspects of the protease from both quality control and precision protein destruction functions. Here, the regulatory …

The Role Of The Metallochaperone Hypa In The Acid Survival And Activities Of Nickel Enzymes In Helicobacter Pylori, Heidi Hu

Doctoral Dissertations

Helicobacter pylori is a bacterium that has colonized the human gastric mucosa of over 50% of the world population. Persistent infection can cause gastritis, peptic ulcers, and cancers. The ability of H. pylori to colonize the acidic environment of the human stomach is dependent on the activity of the nickel containing enzymes, urease and NiFe-hydrogenase. The nickel metallochaperone, HypA, was previously shown to be required for the full activity of both enzymes. In addition to a Ni-binding site, HypA also contains a structural Zn site, which has been characterized to alter its averaged structure depending on pH and the presence …

Assembly And Functional Architecture Of Bacterial Chemoreceptor Nanoarrays, Elizabeth R. Haglin

Doctoral Dissertations

Transmembrane chemotaxis receptors are found in bacteria in extended hexagonal arrays stabilized by the membrane and by cytosolic binding partners, the kinase CheA and coupling protein CheW. Models of array architecture and assembly propose receptors cluster into trimers-of-dimers that associate with one CheA dimer and two CheW monomers to form the minimal "core unit" necessary for signal transduction. Reconstructing in vitro chemoreceptor ternary complexes that are homogenous, functional, and exhibit native architecture remains a challenge. Here we report that His-tag mediated receptor dimerization with divalent metals is sufficient to drive assembly of native-like functional arrays of a receptor cytoplasmic fragment. …

The Heat Shock Cognate 70 Protein (Hsc70) Is A Novel Target For Nobiletin In Colon Cancer Cells, Zili Gao

Doctoral Dissertations

Nobiletin (NBT) is a unique flavonoid mainly found in citrus fruits, and has been reported to inhibit colon carcinogenesis in multiple rodent models. However, the direct molecular targets of NBT are unknown. Heat shock cognate 70 protein (HSC70) contributes to cancer cell survival and resistance to chemotherapies, thereby the inhibition of HSC70 is a promising strategy in cancer chemoprevention. Using affinity chromatography, proteomics analysis and computer modeling, we demonstrated that NBT bound to HSC70 at its ATP-binding site and specifically inhibited its ATPase activity. The association between HSC70 and HSP90 is critical for the stability of their client proteins, which …

Mechanism Of Regulation Of Kinesins Eg5 And Kif15 By Tpx2, Sai Keshavan Balchand

Doctoral Dissertations

Cell division is the fundamental process by which the replicated genetic material is faithfully segregated to form two identical daughter cells. The mitotic spindle is the macromolecular cytoskeletal structure that is built during every round of cell division to successfully separate the duplicated genome equally into the daughter cells. Errors in spindle formation can thus causegenetic aberrations and can potentially lead to cancer. Understanding the mechanisms that govern proper spindle assembly and function is thus important. Eg5 and Kif15 are two important kinesins which play a major role in establishing and maintaining bipolarity of the mitotic spindle. Both Eg5 and …

Light-Harvesting And Light-Responsive Materials For Optoelectronic And Biological Applications, Youngju Bae

Doctoral Dissertations

In photodynamic therapy, several critical standards are required of photosensitizers including high singlet oxygen quantum yield, biocompatibility in dark, and long term photochemical stability. In addition, current PDT systems lack active targeting strategies to tumor cells, and instead mainly rely on the natural distribution of PS in the body following injection and application of near-infrared light treatment in the tumor region. This thesis describes a series of BODIPY-based molecules that were designed, synthesized and studied as photosensitizers with high singlet oxygen generation capacity through utilizing the heavy atom effect. Additionally, aqueous solubility and active targeting capability were introduced by photosensitizer …

The Feronia Receptor Kinase Maintains Cell-Wall Integrity During Salt Stress Through Ca2+ Signaling, Wei Feng, Daniel Kita, Alexis Peaucelle, Heather N. Cartwright, Vinh Doan, Qiaohong Duan, Ming-Che Liu, Jacob Maman, Leonie Steinhorst, Ina Schmitz-Thom, Robert Yvon, Jörg Kudla, Hen-Ming Wu, Alice Y. Cheung, José R. Dinneny

Biochemistry & Molecular Biology Department Faculty Publication Series

Cells maintain integrity despite changes in their mechanical properties elicited during growth and environmental stress. How cells sense their physical state and compensate for cell-wall damage is poorly understood, particularly in plants. Here we report that FERONIA (FER), a plasma-membrane-localized receptor kinase from Arabidopsis, is necessary for the recovery of root growth after exposure to high salinity, a widespread soil stress. The extracellular domain of FER displays tandem regions of homology with malectin, an animal protein known to bind di-glucose in vitro and important for protein quality control in the endoplasmic reticulum. The presence of malectin-like domains in FER …