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Description
Lyme disease is a common tick-borne illness caused by the Gram-negative bacterium Borrelia burgdorferi. An outer membrane protein of Borrelia burgdorferi, P66, has been suggested as a possible target for Lyme disease treatments. However, a lack of structural information available for P66 has hindered attempts to design medications to target the protein. Therefore, this study attempted to find methods for expressing and purifying P66 in quantities that can be used for structural studies. It was found that by using the PelB signal sequence, His-tagged P66 could be directed to the outer membrane of Escherichia coli, as confirmed by an anti-His Western blot. Further attempts to optimize P66 expression in the outer membrane were made, pending verification via Western blotting. The ability to direct P66 to the outer membrane using the PelB signal sequence is a promising first step in determining the overall structure of P66, but further work is needed before P66 is ready for large-scale purification for structural studies.
ContributorsRamirez, Christopher Nicholas (Author) / Fromme, Petra (Thesis director) / Hansen, Debra (Committee member) / Department of Physics (Contributor) / School of Molecular Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
Description
Membrane proteins located within or as attachments to the cell membrane play critical roles in many essential cellular functions and host-pathogen interactions. Knowledge of the structure and function of membrane proteins in pathogenic species can allow for the development of specific vaccines and therapeutic agents against the pathogen. Francisella tularensis is an intracellular pathogen that is the causative agent of the severe, life-threatening infection, tularemia, in humans and other small mammals. F. tularensis is prevalent within the environment and is a potential bioterrorism agent due to its high virulence and its ability to be spread easily as an aerosol. The CapBCA membrane protein complex has been identified as a virulence factor of F. tularensis. This project, derived from the Membrane Proteins in Infections Diseases (MPID) Project, aims to successfully express the membrane proteins CapBCA, which are crucial to the pathogenic properties of F. tularensis. To accomplish this goal, methods for in vivo recombinant expression and purification of membrane proteins are in the process of being developed. The expression of the CapA component has been successful for some time, therefore, the goal of this study is to develop an approach toward recombinant in vivo membrane protein expression of both the CapB and CapC components of the CapBCA membrane protein complex. In this study, the CapB and CapC components were expressed for the first time in vivo through the use of the novel MPID vector, pelB-MBP. The expression of the CapB and CapC components will allow for large-scale expressions to commence with the end goal of determining the crystal structures of the individual proteins or the complex. Ultimately, it is hoped that knowledge of these molecular structures can lead to the development of a vaccine or other therapeutic agents against this pathogen.
ContributorsTrimble, Kelli Lauren (Author) / Fromme, Petra (Thesis director) / Hansen, Debra (Committee member) / Barrett, The Honors College (Contributor) / Department of Chemistry and Biochemistry (Contributor) / School of Film, Dance and Theatre (Contributor)
Created2015-05
Description
All multicellular organisms are susceptible to developing cancer, but some organisms have varying sensitivities to the disease. One such organism is the Trichoplax adhaerens which has no documented case of cancer development. T. adhaerens cancer resistance was studied by observing physiological and morphological changes of the organism after radiation treatment. Preliminary experiments suggested that this organism is able to survive exposure to 160 gray radiation treatment almost as well as untreated organisms. The T. adhaerens have two genes, TriadG6402 and TriadG5479, similar to the human genes TP53 and MDM2 respectively. TP53 and MDM2 are the two main genes associated with apoptosis in humans: an important cell regulatory checkpoint involved in cancer prevention. PCR analysis, done after radiation treatment, showed an overexpression of the ortholog gene MDM2 in the T. adhaerens. This may suggest that T. adhaerens block apoptosis from occurring and that their ortholog gene is involved in DNA repair. It is significant to study the gene expression of TriadG6402 and TriadG54791 in T. adhaerens because these genes are well conserved in humans. Future studies of these genes in the T. adhaerens can be used to understand the evolution of the function of these genes in more complex organisms and be used for human cancer prevention.
ContributorsKulkarni, Arathi (Author) / Fortunato, Angelo (Thesis director) / Maley, Carlo (Committee member) / Department of Economics (Contributor) / School of Molecular Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Enzyme Replacement Therapy (ERT) is a treatment often used for patients with disorders that affect the production of various enzymes within the body, such as Cystic Fibrosis and Fabry Disease. ERT involves the use of artificially-produced enzymes, which can be derived from humans, pigs, and bacteria. Generally, enzymes derived from porcine and bacterial sources are much less expensive and more accessible than those derived from a human source. This, and the ethical implications that porcine enzymes carry, make the decision of choosing treatment simple to some and complex to others. Ethically, human-derived enzymes are often considered more ethical, while not conflicting with religious beliefs and practices as porcine-derived enzymes do.
In order to further compare porcine and human-derived enzymes, a determination of the enzyme effectiveness was done via digestion simulation. The digestion for both the human and porcine-derived enzymes consisted of three steps: oral, gastric, and intestinal. After the digestion, the absorbance for each enzyme class as well as a dilution curve of the formula used was read and recorded. Using the standard dilution curve and the absorbance values for each unknown, the formula and thus enzyme concentration that was lost through the reaction was able to be calculated.
The effectiveness of both the human and porcine enzymes, determined by the percent of formula lost, was 18.2% and 19.7%, respectively, with an error of 0.6% from the spectrophotometer, and an error of about 10% from the scale used for measuring the enzymes. This error was likely due to the small mass required of the enzymes and can be prevented in the future by performing the experiment at a larger scale.
In order to further compare porcine and human-derived enzymes, a determination of the enzyme effectiveness was done via digestion simulation. The digestion for both the human and porcine-derived enzymes consisted of three steps: oral, gastric, and intestinal. After the digestion, the absorbance for each enzyme class as well as a dilution curve of the formula used was read and recorded. Using the standard dilution curve and the absorbance values for each unknown, the formula and thus enzyme concentration that was lost through the reaction was able to be calculated.
The effectiveness of both the human and porcine enzymes, determined by the percent of formula lost, was 18.2% and 19.7%, respectively, with an error of 0.6% from the spectrophotometer, and an error of about 10% from the scale used for measuring the enzymes. This error was likely due to the small mass required of the enzymes and can be prevented in the future by performing the experiment at a larger scale.
ContributorsBlevins, Brianna R (Author) / Martin, Thomas (Thesis director) / McILwraith, Heide (Committee member) / College of Integrative Sciences and Arts (Contributor) / School of Molecular Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
Transient receptor potential (TRP) channels are a superfamily of ion channels found in plasma membranes of both single-celled and multicellular organisms. TRP channels all share the common aspect of having six transmembrane helices and a TRP domain. These structures tetramerize to form a receptor-activated non-selective ion channel. The specific protein being investigated in this thesis is the human transient receptor potential melastatin 8 (hTRPM8), a channel activated by the chemical ligand menthol and temperatures below 25 °C. TRPM8 is responsible for cold sensing and is related to pain relief associated with cooling compounds. TRPM8 has also been found to play a role in the regulation of various types of tumors. The structure of TRPM8 has been obtained through cryo-electron microscopy, but the functional contribution of individual portions of the protein to the overall protein function is unknown.
To gain more information about the function of the transmembrane region of hTRPM8, it was expressed in Escherichia coli (E. coli) and purified in detergent membrane mimics for experimentation. The construct contains the S4-S5 linker, pore domain (S5 and S6 transmembrane helices), pore helix, and TRP box. hTRPM8-PD+ was purified in the detergents n-Dodecyl-B-D-Maltoside (DDM), 16:0 Lyso PG, 1-Palmitoyl-2-hydroxy-sn-glycero-3-phosphoglycerol (LPPG), and 14:0 Lyso PG, 1-Myristoyl-2-hydroxy-sn-glycero-3-phosphoglycerol (LMPG) to determine which detergent resulted in a hTRPM8-PD+ sample of the most stability, purity, and highest concentrations. Following bacterial expression and protein purification, hTRPM8-PD+ was studied and characterized with circular dichroism (CD) spectroscopy to learn more about the secondary structures and thermodynamic properties of the construct. Further studies can be done with more circular dichroism (CD) spectroscopy, planar lipid bilayer (BLM) electrophysiology, and nuclear magnetic resonance spectroscopy (NMR) to gain more understanding of how the pore domain plus contributes to the activity of the whole protein construct.
To gain more information about the function of the transmembrane region of hTRPM8, it was expressed in Escherichia coli (E. coli) and purified in detergent membrane mimics for experimentation. The construct contains the S4-S5 linker, pore domain (S5 and S6 transmembrane helices), pore helix, and TRP box. hTRPM8-PD+ was purified in the detergents n-Dodecyl-B-D-Maltoside (DDM), 16:0 Lyso PG, 1-Palmitoyl-2-hydroxy-sn-glycero-3-phosphoglycerol (LPPG), and 14:0 Lyso PG, 1-Myristoyl-2-hydroxy-sn-glycero-3-phosphoglycerol (LMPG) to determine which detergent resulted in a hTRPM8-PD+ sample of the most stability, purity, and highest concentrations. Following bacterial expression and protein purification, hTRPM8-PD+ was studied and characterized with circular dichroism (CD) spectroscopy to learn more about the secondary structures and thermodynamic properties of the construct. Further studies can be done with more circular dichroism (CD) spectroscopy, planar lipid bilayer (BLM) electrophysiology, and nuclear magnetic resonance spectroscopy (NMR) to gain more understanding of how the pore domain plus contributes to the activity of the whole protein construct.
ContributorsMorelan, Danielle Taylor (Co-author) / Morelan, Danielle (Co-author) / Van Horn, Wade (Thesis director) / Chen, Julian (Committee member) / Luu, Dustin (Committee member) / Dean, W.P. Carey School of Business (Contributor) / School of Molecular Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2019-12
Description
Transient receptor potential (TRP) channels are a diverse family of polymodally gated nonselective cation channels implicated in a variety of pathophysiologies. Two channels of specific interest are transient receptor potential melastatin 8 (TRPM8) and transient receptor potential vanilloid 1 (TRPV1).
TRPM8 is the primary cold sensor in humans and is activated by ligands that feel cool such as menthol and icilin. It is implicated to be involved in a variety of cancers, nociception, obesity, addiction, and thermosensitivity. There are thought to be conserved regions of structural and functional importance to the channel which can be identified by looking at the evolution of TRPM8 over time. Along with this, looking at different isoforms of TRPM8 which are structurally very different but functionally similar can help isolate regions of functional interest as well. Between TRP channels, the transmembrane domain is well conserved and thought to be important for sensory physiology. To learn about these aspects of TRPM8, three evolutionary constructs, the last common primate, the last common mammalian, and the last common vertebrate ancestor TRPM8 were cloned and subjected to preliminary studies. In addition to the initial ancestral TRPM8 studies, fundamental studies were initiated in method development to evaluate the use of biological signaling sequences to attempt to force non-trafficking membrane protein isoforms and biophysical constructs to the plasma membrane. To increase readout for these and other studies, a cellular based fluorescence assay was initiated. Eventual completion of these efforts will lead to better understanding of the mechanism that underlie TRPM8 function and provide enhanced general methods for ion channel studies.
Beyond TRPM8 studies, an experiment was designed to probe mechanistic features of TRPV1 ligand activation. TRPV1 is also a thermosensitive channel in the TRP family, sensing heat and vanilloid ligands like capsaicin, commonly found in chili peppers. This channel is also involved in many proinflammatory interactions and associated with cancers, nociception, and addiction. Better understanding binding interactions can lead to attempts to create therapeutics.
TRPM8 is the primary cold sensor in humans and is activated by ligands that feel cool such as menthol and icilin. It is implicated to be involved in a variety of cancers, nociception, obesity, addiction, and thermosensitivity. There are thought to be conserved regions of structural and functional importance to the channel which can be identified by looking at the evolution of TRPM8 over time. Along with this, looking at different isoforms of TRPM8 which are structurally very different but functionally similar can help isolate regions of functional interest as well. Between TRP channels, the transmembrane domain is well conserved and thought to be important for sensory physiology. To learn about these aspects of TRPM8, three evolutionary constructs, the last common primate, the last common mammalian, and the last common vertebrate ancestor TRPM8 were cloned and subjected to preliminary studies. In addition to the initial ancestral TRPM8 studies, fundamental studies were initiated in method development to evaluate the use of biological signaling sequences to attempt to force non-trafficking membrane protein isoforms and biophysical constructs to the plasma membrane. To increase readout for these and other studies, a cellular based fluorescence assay was initiated. Eventual completion of these efforts will lead to better understanding of the mechanism that underlie TRPM8 function and provide enhanced general methods for ion channel studies.
Beyond TRPM8 studies, an experiment was designed to probe mechanistic features of TRPV1 ligand activation. TRPV1 is also a thermosensitive channel in the TRP family, sensing heat and vanilloid ligands like capsaicin, commonly found in chili peppers. This channel is also involved in many proinflammatory interactions and associated with cancers, nociception, and addiction. Better understanding binding interactions can lead to attempts to create therapeutics.
ContributorsShah, Karan (Author) / Van Horn, Wade (Thesis director) / Neisewander, Janet (Committee member) / Biegasiewicz, Kyle (Committee member) / School of Mathematical and Statistical Sciences (Contributor) / School of Molecular Sciences (Contributor, Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
Bee communities form the keystone of many ecosystems through their pollination services. They are dynamic and often subject to significant changes due to several different factors such as climate, urban development, and other anthropogenic disturbances. As a result, the world has been experiencing a decline in bee diversity and abundance, which can have detrimental effects in the ecosystems they inhabit. One of the largest factors that impacts bees in today's world is the rapid urbanization of our planet, and it impacts the bee community in mixed ways. Not very much is understood about the bee communities that exist in urban habitats, but as urbanization is inevitably going to continue, knowledge on bee communities will need to strengthen. This study aims to determine the levels of variance in bee communities, considering multiple variables that bee communities can differ in. The following three questions are posed: do bee communities that are spatially separated differ significantly? Do bee communities that are separated by seasons differ significantly? Do bee communities that are separated temporally (by year, interannually) differ significantly? The procedure to conduct this experiment consists of netting and trapping bees at two sites at various times using the same methods. The data is then statistically analyzed for differences in abundance, richness, diversity, and species composition. After performing the various statistical analyses, it has been discovered that bee communities that are spatially separated, seasonally separated, or interannually separated do not differ significantly when it comes to abundance and richness. Spatially separated bee communities and interannually separated bee communities show a moderate level of dissimilarity in their species composition, while seasonally separated bee communities show a greater level of dissimilarity in species composition. Finally, seasonally separated bee communities demonstrate the greatest disparity of bee diversity, while interannually separated bee communities show the least disparity of bee diversity. This study was conducted over the time span of two years, and while the levels of variance of an urban area between these variables were determined, further variance studies of greater length or larger areas should be conducted to increase the currently limited knowledge of bee communities in urban areas. Additional studies on precipitation amounts and their effects on bee communities should be conducted, and studies from other regions should be taken into consideration while attempting to understand what is likely the most environmentally significant group of insects.
ContributorsPhan, James Thien (Author) / Sweat, Ken (Thesis director) / Foltz-Sweat, Jennifer (Committee member) / School of Music (Contributor) / School of Molecular Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
Structure is a critical component in drug development. This project supports antibody- facilitated structure determination for the following eleven membrane proteins: the human histamine and dopamine G protein-coupled receptors (HRH4 and DRD2) involved in a wide variety of pathologies such as allergies, inflammation, asthma, pain along with Parkinson's and schizophrenia respectively, the human cystic fibrosis transmembrane conductance regulator (CFTR), the human NaV1.8 voltage-gated sodium ion channel, the human TPC2 two-pore channel, the SARS virus proteins 3a, E and M, the MERS virus protein E and M, and the malarial chloroquine resistance transporter (PfCRT). Serum antibodies against these proteins were generated by genetic immunization, and both in vitro and in vivo expressed membrane proteins were created to characterize the serum antibodies. Plasmid clones were generated for genetic immunization, in vitro protein expression, and in vivo expression (HEK293T transfection). Serum antibodies were generated by genetic immunization of mice by gene gun. Genetic immunization promotes an immune response that allows for the generation of antibodies in the absence of purified protein. In vitro expression was accomplished through the novel technique: in vitro translation with hydrophobic magnetic beads (IVT-HMB). Transfections were performed using the HEK293T cell line to express the protein in vivo. The generated protein was then used in gel electrophoresis and silver stain and/or Western blot analyses to identify and visualize the proteins. These expressed proteins will allow for forthcoming characterization of the generated antibodies. The resulting antibodies will in turn enable structure determination of these important membrane proteins by co-crystallization.
ContributorsDrotar, Beniamin (Author) / Fromme, Petra (Thesis director) / Hansen, Debra T. (Committee member) / School of Molecular Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
The college textbook is the most commonly required component of almost any college course, regardless of a student's academic discipline. Professors often expect students to have access to the textbook and to use it to complete assigned readings. Textbooks often contain features that are designed to facilitate active reading, or critical engagement with the information being read, to enhance learning of the material. However, students often do not read or prioritize reading the textbook. Students who do read, tend not to read the textbook as intended or use many of the features designed to promote active reading and enhanced learning of the material. Educational studies of textbooks tend to focus on aspects related to topics more relevant to publishers or professors with less research on aspects of the textbook applicable to students at the college level. The purpose of this study is to evaluate students' textbook use and their attitudes toward the textbook in an introductory biology course. Results of this study indicate students hold positive attitudes toward their textbook in an introductory biology course and majority of students do not use components meant to facilitate active learning. Although students report completing assigned readings, students may actually be reading select portions of what is assigned in using the textbook to prepare for exams. These results suggest that students may only be using their textbook to enhance their understanding of materials they expect to be tested on. The findings of this study help to understand the role of the textbook from the perspective of the student and provide insight for improving textbook design and use in science courses at the college level.
ContributorsRudolph, Alexia Marion (Author) / Vanmali, Binaben (Thesis director) / Chen, Ying-Chih (Committee member) / Yoho, Rachel (Committee member) / Department of Psychology (Contributor) / School of Molecular Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
Transient Receptor Potential (TRP) ion channels are a diverse family of nonselective, polymodal sensors in uni- and multicellular eukaryotes that are implicated in an assortment of biological contexts and human disease. The cold-activated TRP Melastatin-8 (TRPM8) channel, also recognized as the human body's primary cold sensor, is among the few TRP channels responsible for thermosensing. Despite sustained interest in the channel, the mechanisms underlying TRPM8 activation, modulation, and gating have proved challenging to study and remain poorly understood. In this thesis, I offer data collected on various expression, extraction, and purification conditions tested in E. Coli expression systems with the aim to optimize the generation of a structurally stable and functional human TRPM8 pore domain (S5 and S6) construct for application in structural biology studies. These studies, including the biophysical technique nuclear magnetic spectroscopy (NMR), among others, will be essential for elucidating the role of the TRPM8 pore domain in in regulating ligand binding, channel gating, ion selectively, and thermal sensitivity. Moreover, in the second half of this thesis, I discuss the ligation-independent megaprimer PCR of whole-plasmids (MEGAWHOP PCR) cloning technique, and how it was used to generate chimeras between TRPM8 and its nearest analog TRPM2. I review steps taken to optimize the efficiency of MEGAWHOP PCR and the implications and unique applications of this novel methodology for advancing recombinant DNA technology. I lastly present preliminary electrophysiological data on the chimeras, employed to isolate and study the functional contributions of each individual transmembrane helix (S1-S6) to TRPM8 menthol activation. These studies show the utility of the TRPM8\u2014TRPM2 chimeras for dissecting function of TRP channels. The average current traces analyzed thus far indicate that the S2 and S3 helices appear to play an important role in TRPM8 menthol modulation because the TRPM8[M2S2] and TRPM8[M2S3] chimeras significantly reduce channel conductance in the presence of menthol. The TRPM8[M2S4] chimera, oppositely, increases channel conductance, implying that the S4 helix in native TRPM8 may suppress menthol modulation. Overall, these findings show that there is promise in the techniques chosen to identify specific regions of TRPM8 crucial to menthol activation, though the methods chosen to study the TRPM8 pore independent from the whole channel may need to be reevaluated. Further experiments will be necessary to refine TRPM8 pore solubilization and purification before structural studies can proceed, and the electrophysiology traces observed for the chimeras will need to be further verified and evaluated for consistency and physiological significance.
ContributorsWaris, Maryam Siddika (Author) / Van Horn, Wade (Thesis director) / Redding, Kevin (Committee member) / School of Molecular Sciences (Contributor) / Department of English (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05