Barrett, The Honors College Thesis/Creative Project Collection
Barrett, The Honors College at Arizona State University proudly showcases the work of undergraduate honors students by sharing this collection exclusively with the ASU community.
Barrett accepts high performing, academically engaged undergraduate students and works with them in collaboration with all of the other academic units at Arizona State University. All Barrett students complete a thesis or creative project which is an opportunity to explore an intellectual interest and produce an original piece of scholarly research. The thesis or creative project is supervised and defended in front of a faculty committee. Students are able to engage with professors who are nationally recognized in their fields and committed to working with honors students. Completing a Barrett thesis or creative project is an opportunity for undergraduate honors students to contribute to the ASU academic community in a meaningful way.
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- Creators: Department of Chemistry and Biochemistry
Description
Bacteria have been shown to possess a large array of regulatory mechanisms to not just respond to a diverse array of environmental stresses, but to injurious artificial proteins as well. A previous investigation introduced DX, a man-made ATP sequestering protein into Escherichia coli (E. coli) which resulted in the formation of novel endoliposome structures and induced a viable but non-culturable state (VBNC) that was not easily reversed. It was hypothesized that the broadly conserved bacterial stringent response pathway may have been responsible for the observed phenotypic changes. With the goal of unveiling the molecular mechanism behind this novel response, changes in cellular morphology and physiology upon DX expression were assessed in a population of E. coli encoding a dysfunctional relA gene, one of the two genes controlling the induction of the stringent response. It was ultimately shown that RelA directly contributed to cellular filamentation, endoliposome structure formation, and the induction of a VBNC state. While the stringent response has been extensively shown to induce a VBNC state, to our knowledge, relA has not yet been shown to induce filamentation or coordinate the formation of endoliposome structures in bacteria. As the stringent response has been shown to be increasingly involved in antibiotic tolerance, this study provided an exciting opportunity to further characterize this adaptive response pathway to aid in the future development of novel therapeutics. In addition to this, this study continued to highlight that the DX protein may serve one of the first tools to allow for the direct selection of bacteria in a VBNC state by morphologically distinguishing non-culturable cells through cellular filamentation.
ContributorsFrost, Fredrick Charles (Author) / Chaput, John (Thesis director) / Wachter, Rebekka (Committee member) / Korch, Shaleen (Committee member) / Barrett, The Honors College (Contributor) / Department of Chemistry and Biochemistry (Contributor)
Created2014-12
Description
ABSTRACT:
The experiment was conducted to analyze the role of menaquinone (MQ) in heliobacteria’s reaction center (HbRC). Their photosynthetic apparatus is a homodimeric of type I reaction center (1). HbRC contains these cofactors: P800 (special pair cholorphyll), A0 (8-hydroxy-chlorophyll [Chl] a), and FX (iron-sulfur cluster). The MQ factor is bypassed during the electron transfer process in HbRC. Electrons from the excited state of P800 (P800*) are transported to A0 and then directly to Fx. The hypothesis is that when electrons are photoaccumulated at Fx, and without the presence of any electron acceptors to the cluster, they would be transferred to MQ, and reduce it to MQH2 (quinol). Experiments conducted in the past with HbRC within the cell membranes yielded data that supported this hypothesis (Figures 4 and 5). We conducted a new experiment based on that foundation with HbRC, isolated from cell membrane. Two protein assays were prepared with cyt c553 and ascorbate in order to observe this phenomenon. The two samples were left in the glove box for several days for equilibration and then exposed to light in different intensity and periods. Their absorption was monitored at 800 nm for P800 or 554 nm for cyt c553 to observe their oxidation and reduction processes. The measurements were performed with the JTS-10 spectrophotometer. The data obtained from these experiments support the theory that P800+ reduced by the charge recombination of P800+Fx-. However, it did not confirm the reduction of P800+ done by cyt c553¬ which eventually lead to a net accumulation of oxidized cyt c553; instead it revealed another factor that could reduce P800+ faster and more efficient than cyt c553 (0.5 seconds vs several seconds), which could be MQ. More experiments need to be done in order to confirm this result. Hence, the data collected from this experiment have yet to support the theory of MQ being reduced to MQH2 outside the bacterial membranes.
The experiment was conducted to analyze the role of menaquinone (MQ) in heliobacteria’s reaction center (HbRC). Their photosynthetic apparatus is a homodimeric of type I reaction center (1). HbRC contains these cofactors: P800 (special pair cholorphyll), A0 (8-hydroxy-chlorophyll [Chl] a), and FX (iron-sulfur cluster). The MQ factor is bypassed during the electron transfer process in HbRC. Electrons from the excited state of P800 (P800*) are transported to A0 and then directly to Fx. The hypothesis is that when electrons are photoaccumulated at Fx, and without the presence of any electron acceptors to the cluster, they would be transferred to MQ, and reduce it to MQH2 (quinol). Experiments conducted in the past with HbRC within the cell membranes yielded data that supported this hypothesis (Figures 4 and 5). We conducted a new experiment based on that foundation with HbRC, isolated from cell membrane. Two protein assays were prepared with cyt c553 and ascorbate in order to observe this phenomenon. The two samples were left in the glove box for several days for equilibration and then exposed to light in different intensity and periods. Their absorption was monitored at 800 nm for P800 or 554 nm for cyt c553 to observe their oxidation and reduction processes. The measurements were performed with the JTS-10 spectrophotometer. The data obtained from these experiments support the theory that P800+ reduced by the charge recombination of P800+Fx-. However, it did not confirm the reduction of P800+ done by cyt c553¬ which eventually lead to a net accumulation of oxidized cyt c553; instead it revealed another factor that could reduce P800+ faster and more efficient than cyt c553 (0.5 seconds vs several seconds), which could be MQ. More experiments need to be done in order to confirm this result. Hence, the data collected from this experiment have yet to support the theory of MQ being reduced to MQH2 outside the bacterial membranes.
ContributorsNguyen, Phong Thien Huynh (Author) / Redding, Kevin (Thesis director) / Van Horn, Wade (Committee member) / Wachter, Rebekka (Committee member) / Barrett, The Honors College (Contributor) / Department of Chemistry and Biochemistry (Contributor)
Created2015-05