ASU Electronic Theses and Dissertations
This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.
In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.
Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.
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- Creators: Cooke, Nancy J.
- Creators: Ghirlanda, Giovanna
Description
Cyanovirin-N (CV-N) is a naturally occurring lectin originally isolated from the cyanobacteria Nostoc ellipsosporum. This 11 kDa lectin is 101 amino acids long with two binding sites, one at each end of the protein. CV-N specifically binds to terminal Manα1-2Manα motifs on the branched, high mannose Man9 and Man8 glycosylations found on enveloped viruses including Ebola, Influenza, and HIV. wt-CVN has micromolar binding to soluble Manα1-2Manα and also inhibits HIV entry at low nanomolar concentrations. CV-N's high affinity and specificity for Manα1-2Manα makes it an excellent lectin to study for its glycan-specific properties. The long-term aim of this project is to make a variety of mutant CV-Ns to specifically bind other glycan targets. Such a set of lectins may be used as screening reagents to identify biomarkers and other glycan motifs of interest. As proof of concept, a T7 phage display library was constructed using P51G-m4-CVN genes mutated at positions 41, 44, 52, 53, 56, 74, and 76 in binding Domain B. Five CV-N mutants were selected from the library and expressed in BL21(DE3) E. coli. Two of the mutants, SSDGLQQ-P51Gm4-CVN and AAGRLSK-P51Gm4-CVN, were sufficiently stable for characterization and were examined by CD, Tm, ELISA, and glycan array. Both proteins have CD minima at approximately 213 nm, indicating largely β-sheet structure, and have Tm values greater than 40°C. ELISA against gp120 and RNase B demonstrate both proteins' ability to bind high mannose glycans. To more specifically determine the binding specificity of each protein, AAGRLSK-P51Gm4-CVN, SSDGLQQ-P51Gm4-CVN, wt-CVN, and P51G-m4-CVN were sent to the Consortium for Functional Glycomics (CFG) for glycan array analysis. AAGRLSK-P51Gm4-CVN, wt-CVN, and P51G-m4-CVN, have identical specificities for high mannose glycans containing terminal Manα1-2Manα. SSDGLQQ-P51Gm4-CVN binds to terminal GlcNAcα1-4Gal motifs and a subgroup of high mannose glycans bound by P51G-m4-CVN. SSDGLQQ-wt-CVN was produced to restore anti-HIV activity and has a high nanomolar EC50 value compared to wt-CVN's low nanomolar activity. Overall, these experiments show that CV-N Domain B can be mutated and retain specificity identical to wt-CVN or acquire new glycan specificities. This first generation information can be used to produce glycan-specific lectins for a variety of applications.
ContributorsRuben, Melissa (Author) / Ghirlanda, Giovanna (Thesis advisor) / Allen, James (Committee member) / Wachter, Rebekka (Committee member) / Arizona State University (Publisher)
Created2013
Description
As technology enhances our communication capabilities, the number of distributed teams has risen in both public and private sectors. There is no doubt that these technological advancements have addressed a need for communication and collaboration of distributed teams. However, is all technology useful for effective collaboration? Are some methods (modalities) of communication more conducive than others to effective performance and collaboration of distributed teams? Although previous literature identifies some differences in modalities, there is little research on geographically distributed mobile teams (DMTs) performing a collaborative task. To investigate communication and performance in this context, I developed the GeoCog system. This system is a mobile communications and collaboration platform enabling small, distributed teams of three to participate in a variant of the military-inspired game, "Capture the Flag". Within the task, teams were given one hour to complete as many "captures" as possible while utilizing resources to the advantage of the team. In this experiment, I manipulated the modality of communication across three conditions with text-based messaging only, vocal communication only, and a combination of the two conditions. It was hypothesized that bi-modal communication would yield superior performance compared to either single modality conditions. Results indicated that performance was not affected by modality. Further results, including communication analysis, are discussed within this paper.
ContributorsChampion, Michael (Author) / Cooke, Nancy J. (Thesis advisor) / Shope, Steven (Committee member) / Wu, Bing (Committee member) / Arizona State University (Publisher)
Created2012
Description
Spinal muscular atrophy (SMA) is a neurodegenerative disease that results in the loss of lower body muscle function. SMA is the second leading genetic cause of death in infants and arises from the loss of the Survival of Motor Neuron (SMN) protein. SMN is produced by two genes, smn1 and smn2, that are identical with the exception of a C to T conversion in exon 7 of the smn2 gene. SMA patients lacking the smn1 gene, rely on smn2 for production of SMN. Due to an alternative splicing event, smn2 primarily encodes a non-functional SMN lacking exon 7 (SMN D7) as well as a low amount of functional full-length SMN (SMN WT). SMN WT is ubiquitously expressed in all cell types, and it remains unclear how low levels of SMN WT in motor neurons lead to motor neuron degradation and SMA. SMN and its associated proteins, Gemin2-8 and Unrip, make up a large dynamic complex that functions to assemble ribonucleoproteins. The aim of this project was to characterize the interactions of the core SMN-Gemin2 complex, and to identify differences between SMN WT and SMN D7. SMN and Gemin2 proteins were expressed, purified and characterized via size exclusion chromatography. A stable N-terminal deleted Gemin2 protein (N45-G2) was characterized. The SMN WT expression system was optimized resulting in a 10-fold increase of protein expression. Lastly, the oligomeric states of SMN and SMN bound to Gemin2 were determined. SMN WT formed a mixture of oligomeric states, while SMN D7 did not. Both SMN WT and D7 bound to Gemin2 with a one-to-one ratio forming a heterodimer and several higher-order oligomeric states. The SMN WT-Gemin2 complex favored high molecular weight oligomers whereas the SMN D7-Gemin2 complex formed low molecular weight oligomers. These results indicate that the SMA mutant protein, SMN D7, was still able to associate with Gemin2, but was not able to form higher-order oligomeric complexes. The observed multiple oligomerization states of SMN and SMN bound to Gemin2 may play a crucial role in regulating one or several functions of the SMN protein. The inability of SMN D7 to form higher-order oligomers may inhibit or alter those functions leading to the SMA disease phenotype.
ContributorsNiday, Tracy (Author) / Allen, James P. (Thesis advisor) / Wachter, Rebekka (Committee member) / Ghirlanda, Giovanna (Committee member) / Arizona State University (Publisher)
Created2012
Description
This thesis explores a wide array of topics related to the protein folding problem, ranging from the folding mechanism, ab initio structure prediction and protein design, to the mechanism of protein functional evolution, using multi-scale approaches. To investigate the role of native topology on folding mechanism, the native topology is dissected into non-local and local contacts. The number of non-local contacts and non-local contact orders are both negatively correlated with folding rates, suggesting that the non-local contacts dominate the barrier-crossing process. However, local contact orders show positive correlation with folding rates, indicating the role of a diffusive search in the denatured basin. Additionally, the folding rate distribution of E. coli and Yeast proteomes are predicted from native topology. The distribution is fitted well by a diffusion-drift population model and also directly compared with experimentally measured half life. The results indicate that proteome folding kinetics is limited by protein half life. The crucial role of local contacts in protein folding is further explored by the simulations of WW domains using Zipping and Assembly Method. The correct formation of N-terminal β-turn turns out important for the folding of WW domains. A classification model based on contact probabilities of five critical local contacts is constructed to predict the foldability of WW domains with 81% accuracy. By introducing mutations to stabilize those critical local contacts, a new protein design approach is developed to re-design the unfoldable WW domains and make them foldable. After folding, proteins exhibit inherent conformational dynamics to be functional. Using molecular dynamics simulations in conjunction with Perturbation Response Scanning, it is demonstrated that the divergence of functions can occur through the modification of conformational dynamics within existing fold for β-lactmases and GFP-like proteins: i) the modern TEM-1 lactamase shows a comparatively rigid active-site region, likely reflecting adaptation for efficient degradation of a specific substrate, while the resurrected ancient lactamases indicate enhanced active-site flexibility, which likely allows for the binding and subsequent degradation of different antibiotic molecules; ii) the chromophore and attached peptides of photocoversion-competent GFP-like protein exhibits higher flexibility than the photocoversion-incompetent one, consistent with the evolution of photocoversion capacity.
ContributorsZou, Taisong (Author) / Ozkan, Sefika B (Thesis advisor) / Thorpe, Michael F (Committee member) / Woodbury, Neal W (Committee member) / Vaiana, Sara M (Committee member) / Ghirlanda, Giovanna (Committee member) / Arizona State University (Publisher)
Created2014
Interactions driving the collapse of islet amyloid polypeptide: implications for amyloid aggregation
Description
Human islet amyloid polypeptide (hIAPP), also known as amylin, is a 37-residue intrinsically disordered hormone involved in glucose regulation and gastric emptying. The aggregation of hIAPP into amyloid fibrils is believed to play a causal role in type 2 diabetes. To date, not much is known about the monomeric state of hIAPP or how it undergoes an irreversible transformation from disordered peptide to insoluble aggregate. IAPP contains a highly conserved disulfide bond that restricts hIAPP(1-8) into a short ring-like structure: N_loop. Removal or chemical reduction of N_loop not only prevents cell response upon binding to the CGRP receptor, but also alters the mass per length distribution of hIAPP fibers and the kinetics of fibril formation. The mechanism by which N_loop affects hIAPP aggregation is not yet understood, but is important for rationalizing kinetics and developing potential inhibitors. By measuring end-to-end contact formation rates, Vaiana et al. showed that N_loop induces collapsed states in IAPP monomers, implying attractive interactions between N_loop and other regions of the disordered polypeptide chain . We show that in addition to being involved in intra-protein interactions, the N_loop is involved in inter-protein interactions, which lead to the formation of extremely long and stable β-turn fibers. These non-amyloid fibers are present in the 10 μM concentration range, under the same solution conditions in which hIAPP forms amyloid fibers. We discuss the effect of peptide cyclization on both intra- and inter-protein interactions, and its possible implications for aggregation. Our findings indicate a potential role of N_loop-N_loop interactions in hIAPP aggregation, which has not previously been explored. Though our findings suggest that N_loop plays an important role in the pathway of amyloid formation, other naturally occurring IAPP variants that contain this structural feature are incapable of forming amyloids. For example, hIAPP readily forms amyloid fibrils in vitro, whereas the rat variant (rIAPP), differing by six amino acids, does not. In addition to being highly soluble, rIAPP is an effective inhibitor of hIAPP fibril formation . Both of these properties have been attributed to rIAPP's three proline residues: A25P, S28P and S29P. Single proline mutants of hIAPP have also been shown to kinetically inhibit hIAPP fibril formation. Because of their intrinsic dihedral angle preferences, prolines are expected to affect conformational ensembles of intrinsically disordered proteins. The specific effect of proline substitutions on IAPP structure and dynamics has not yet been explored, as the detection of such properties is experimentally challenging due to the low molecular weight, fast reconfiguration times, and very low solubility of IAPP peptides. High-resolution techniques able to measure tertiary contact formations are needed to address this issue. We employ a nanosecond laser spectroscopy technique to measure end-to-end contact formation rates in IAPP mutants. We explore the proline substitutions in IAPP and quantify their effects in terms of intrinsic chain stiffness. We find that the three proline mutations found in rIAPP increase chain stiffness. Interestingly, we also find that residue R18 plays an important role in rIAPP's unique chain stiffness and, together with the proline residues, is a determinant for its non-amyloidogenic properties. We discuss the implications of our findings on the role of prolines in IDPs.
ContributorsCope, Stephanie M (Author) / Vaiana, Sara M (Thesis advisor) / Ghirlanda, Giovanna (Committee member) / Ros, Robert (Committee member) / Lindsay, Stuart M (Committee member) / Ozkan, Sefika B (Committee member) / Arizona State University (Publisher)
Created2013
Description
Research on priming has shown that exposure to the concept of fast food can have an effect on human behavior by inducing haste and impatience (Zhong & E. DeVoe, 2010). This research suggests that thinking about fast food makes individuals impatient and strengthens their desire to complete tasks such as reading and decision making as quickly and efficiently as possible. Two experiments were conducted in which the effects of fast food priming were examined using a driving simulator. The experiments examined whether fast food primes can induce impatient driving. In experiment 1, 30 adult drivers drove a course in a driving simulator after being exposed to images by rating aesthetics of four different logos. Experiment 1 did not yield faster driving speeds nor an impatient and faster break at the yellow light in the fast food logo prime condition. In experiment 2, 30 adult drivers drove the same course from experiment 1. Participants did not rate logos on their aesthetics prior to the drive, instead billboards were included in the simulation that had either fast food or diner logos. Experiment 2 did not yielded faster driving speeds, however there was a significant effect of faster breaking and a higher number of participants running the yellow light.
ContributorsTaggart, Mistey. L (Author) / Branaghan, Russell (Thesis advisor) / Cooke, Nancy J. (Committee member) / Song, Hyunjin (Committee member) / Arizona State University (Publisher)
Created2014
Description
Telomerase is a unique reverse transcriptase that has evolved specifically to extend the single stranded DNA at the 3' ends of chromosomes. To achieve this, telomerase uses a small section of its integral RNA subunit (TR) to reiteratively copy a short, canonically 6-nt, sequence repeatedly in a processive manner using a complex and currently poorly understood mechanism of template translocation to stop nucleotide addition, regenerate its template, and then synthesize a new repeat. In this study, several novel interactions between the telomerase protein and RNA components along with the DNA substrate are identified and characterized which come together to allow active telomerase repeat addition. First, this study shows that the sequence of the RNA/DNA duplex holds a unique, single nucleotide signal which pauses DNA synthesis at the end of the canonical template sequence. Further characterization of this sequence dependent pause signal reveals that the template sequence alone can produce telomerase products with the characteristic 6-nt pattern, but also works cooperatively with another RNA structural element for proper template boundary definition. Finally, mutational analysis is used on several regions of the protein and RNA components of telomerase to identify crucial determinates of telomerase assembly and processive repeat synthesis. Together, these results shed new light on how telomerase coordinates its complex catalytic cycle.
ContributorsBrown, Andrew F (Author) / Chen, Julian J. L. (Thesis advisor) / Jones, Anne (Committee member) / Ghirlanda, Giovanna (Committee member) / Arizona State University (Publisher)
Created2014
Description
When discussing human factors and performance, researchers recognize stress as a factor, but overlook mood as contributing factor. To explore the relationship between mood, stress and cognitive performance, a field study was conducted involving fire fighters engaged in a fire response simulation. Firefighter participants completed a stress questionnaire, an emotional state questionnaire, and a cognitive task. Stress and cognitive task performance scores were examined before and after the firefighting simulation for individual cognitive performance depreciation caused by stress or mood. They study revealed that existing stress was a reliable predictor of the pre-simulation cognitive task score, that, as mood becomes more positive, perceived stress scores decrease, and that negative mood and pre-simulation stress are also positively and significantly correlated.
ContributorsGomez-Herbert, Maria Elena (Author) / Cooke, Nancy J. (Thesis advisor) / Becker, Vaughn (Committee member) / Branaghan, Russell (Committee member) / Hyunjin, Song (Committee member) / Arizona State University (Publisher)
Created2014
Description
ABSTRACT
Post Translational Modifications (PTMs) are a series of chemical modifications with the capacity to expand the structural and functional repertoire of proteins. PTMs can regulate protein-protein interaction, localization, protein turn-over, the active state of the protein, and much more. This can dramatically affect cell processes as relevant as gene expression, cell-cell recognition, and cell signaling. Along these lines, this Ph.D. thesis examines the role of two of the most important PTMs: glycosylation and phosphorylation.
In chapters 2, 3 and 4, a 10,000 peptide microarray is used to analyze the glycan variations in a series lipopolysaccharides (LPS) from Gram negative bacteria. This research was the first to demonstrate that using a small subset of random sequence peptides, it was possible to identify a small subset with the capacity to bind to the LPS of bacteria. These peptides bound to LPS not only in the solid surface of the array but also in solution as demonstrated with surface plasmon resonance (SPR), isothermal titration calorimetry (ITC) and flow cytometry. Interestingly, some of the LPS binding peptides also exhibit antimicrobial activity, a property that is also analyzed in this work.
In chapters 5 and 6, the role of protein phosphorylation, another PTM, is analyzed in the context of human cancer. High risk neuroblastoma, a very aggressive pediatric cancer, was studied with emphasis on the phosphorylations of two selected oncoproteins: the transcription factor NMYC and the adaptor protein ShcC. Both proteins were isolated from high risk neuroblastoma cells, and a targeted-directed tandem mass spectrometry (LC-MS/MS) methodology was used to identify the phosphorylation sites in each protein. Using this method dramatically improved the phosphorylation site detection and increased the number of sites detected up to 250% in comparison with previous studies. Several of the novel identified sites were located in functional domain of the proteins and that some of them are homologous to known active sites in other proteins of the same family. The chapter concludes with a computational prediction of the kinases that potentially phosphorylate those sites and a series of assays to show this phosphorylation occurred in vitro.
Post Translational Modifications (PTMs) are a series of chemical modifications with the capacity to expand the structural and functional repertoire of proteins. PTMs can regulate protein-protein interaction, localization, protein turn-over, the active state of the protein, and much more. This can dramatically affect cell processes as relevant as gene expression, cell-cell recognition, and cell signaling. Along these lines, this Ph.D. thesis examines the role of two of the most important PTMs: glycosylation and phosphorylation.
In chapters 2, 3 and 4, a 10,000 peptide microarray is used to analyze the glycan variations in a series lipopolysaccharides (LPS) from Gram negative bacteria. This research was the first to demonstrate that using a small subset of random sequence peptides, it was possible to identify a small subset with the capacity to bind to the LPS of bacteria. These peptides bound to LPS not only in the solid surface of the array but also in solution as demonstrated with surface plasmon resonance (SPR), isothermal titration calorimetry (ITC) and flow cytometry. Interestingly, some of the LPS binding peptides also exhibit antimicrobial activity, a property that is also analyzed in this work.
In chapters 5 and 6, the role of protein phosphorylation, another PTM, is analyzed in the context of human cancer. High risk neuroblastoma, a very aggressive pediatric cancer, was studied with emphasis on the phosphorylations of two selected oncoproteins: the transcription factor NMYC and the adaptor protein ShcC. Both proteins were isolated from high risk neuroblastoma cells, and a targeted-directed tandem mass spectrometry (LC-MS/MS) methodology was used to identify the phosphorylation sites in each protein. Using this method dramatically improved the phosphorylation site detection and increased the number of sites detected up to 250% in comparison with previous studies. Several of the novel identified sites were located in functional domain of the proteins and that some of them are homologous to known active sites in other proteins of the same family. The chapter concludes with a computational prediction of the kinases that potentially phosphorylate those sites and a series of assays to show this phosphorylation occurred in vitro.
ContributorsMorales Betanzos, Carlos (Author) / LaBaer, Joshua (Thesis advisor) / Allen, James (Committee member) / Ghirlanda, Giovanna (Committee member) / Arizona State University (Publisher)
Created2014
Description
Preoperative team briefings have been suggested to be important for improving team performance in the operating room. Many high risk environments have accepted team briefings; however healthcare has been slower to follow. While applying briefings in the operating room has shown positive benefits including improved communication and perceptions of teamwork, most research has only focused on feasibility of implementation and not on understanding how the quality of briefings can impact subsequent surgical procedures. Thus, there are no formal protocols or methodologies that have been developed.
The goal of this study was to relate specific characteristics of team briefings back to objective measures of team performance. The study employed cognitive interviews, prospective observations, and principle component regression to characterize and model the relationship between team briefing characteristics and non-routine events (NREs) in gynecological surgery. Interviews were conducted with 13 team members representing each role on the surgical team and data were collected for 24 pre-operative team briefings and 45 subsequent surgical cases. The findings revealed that variations within the team briefing are associated with differences in team-related outcomes, namely NREs, during the subsequent surgical procedures. Synthesis of the data highlighted three important trends which include the need to promote team communication during the briefing, the importance of attendance by all surgical team members, and the value of holding a briefing prior to each surgical procedure. These findings have implications for development of formal briefing protocols.
Pre-operative team briefings are beneficial for team performance in the operating room. Future research will be needed to continue understanding this relationship between how briefings are conducted and team performance to establish more consistent approaches and as well as for the continuing assessment of team briefings and other similar team-related events in the operating room.
The goal of this study was to relate specific characteristics of team briefings back to objective measures of team performance. The study employed cognitive interviews, prospective observations, and principle component regression to characterize and model the relationship between team briefing characteristics and non-routine events (NREs) in gynecological surgery. Interviews were conducted with 13 team members representing each role on the surgical team and data were collected for 24 pre-operative team briefings and 45 subsequent surgical cases. The findings revealed that variations within the team briefing are associated with differences in team-related outcomes, namely NREs, during the subsequent surgical procedures. Synthesis of the data highlighted three important trends which include the need to promote team communication during the briefing, the importance of attendance by all surgical team members, and the value of holding a briefing prior to each surgical procedure. These findings have implications for development of formal briefing protocols.
Pre-operative team briefings are beneficial for team performance in the operating room. Future research will be needed to continue understanding this relationship between how briefings are conducted and team performance to establish more consistent approaches and as well as for the continuing assessment of team briefings and other similar team-related events in the operating room.
ContributorsHildebrand, Emily A (Author) / Branaghan, Russell J (Thesis advisor) / Cooke, Nancy J. (Committee member) / Hallbeck, M. Susan (Committee member) / Bekki, Jennifer M (Committee member) / Blocker, Renaldo C (Committee member) / Arizona State University (Publisher)
Created2014