Connor Bachmann

Mentor: John McLean
Home Institution:  Warren Wilson College
Research Title: "Effects of ARC compounds on the production of secondary metabolomes in actinomycetes"

Abstract:
Recent trends in pharmacological research have indicated renewed interest in natural product discovery as a source of new drug. Microorganisms are an important source of natural products, and recent genome sequencing has produced data that suggest untapped genetic potential. In the context of activating this untapped potential, and thereby accelerating the discovery of natural products, it is known that the addition of certain chemical and biological stressors and stimuli to living microorganisms causes the production of secondary metabolites, or increases in the production of existing secondary metabolites. One chemical stressor, ARC2, is known to increase production of actinorhodin in Streptomyces coelicolor. This study hypothesizes that ARC2 will engender large scale changes in inventories of exposed microorganisms, and tests the effects of ARC2 and other ARC compounds on Streptomyces coelicolor, three actinomycetes of different genera and species. Cultures were analyzed using Ultra High Performance Liquid Chromatography/Mass spectrometry (UPLC/MS) and comparative metabolic analysis.

Laura Hess

Mentor: Eric Skaar
Home Institution:  Michigan State University
Research Title: "Viral and bacterial determinants in bacteriophage infection of Acinetobacter baumannii"

Acinetobacter baumannii is a Gram-negative, opportunistic pathogen that is emerging as a major threat in hospital settings due to increasing multi-drug resistance. A potential therapeutic strategy for combating this problem could involve the utilization of a bacteriophage specific to A. baumannii in order to kill the pathogen and leave the host unharmed. This project focuses on the isolation and characterization of bacteriophages capable of infecting A. baumannii. Phages were isolated from environmental sources as well as by subjecting clinical isolates of A. baumannii to stress. In addition, as bacteriophages bind to the outer membrane of the susceptible bacteria, we are interested in identifying bacterial genetic factors that contribute to outer membrane susceptibility in A. baumannii. Approximately 8,000 independently isolated transposon mutants have been screened for survival under conditions that stress the outer membrane. We isolated 36 mutants expected to have alterations in the outer membrane. Further work will determine whether these mutations affect susceptibility to bacteriophage infection. Determining viral and bacterial characteristics associated with bacteriophage infection in A. baumannii will enhance understanding of host-pathogen interactions between bacteriophage and bacteria, which may allow for development of phage therapies for the treatment of A. baumannii infections.

Emily Janiera

Mentor: Gary Sulikowski
Home Institution: University of North Carolina-Chapel Hill
Research Title: "A Novel Synthetic Route to a UV-Cleavable Bicyclononyne-Biotin Tag"

Abstract:
We propose the synthesis of a novel UV-cleavable bicyclononyne-biotin tag based on work in the Porter lab. The known synthetic route to the useful UV-cleavable linker synthesized by the Porter lab necessitates the use of hazardous reagents. However, this linker is useful for protein pull-down assays that take advantage of biotin-streptavidin binding. This type of biological pull-down may be used to discover the molecular targets of certain anticancer compounds, including apoptolidin, a highly selective and potent anticancer agent. Therefore, having an improved route to the synthesis of this UV-cleavable tag is of particular interest. Starting from the inexpensive and commercially available m-bromophenol, a synthesis of the UV-cleavable linker will be outlined. With this linker in hand, we can attach biotin and append a strained bicyclononyne. Click chemistry will be used to join the bicyclononyne appended UV-linker to azido-apoptolidin A. The resulting biotinylated-apoptolidin tag will be used in proteomic pull-down experiments to identify the molecular target of apoptolidin.

Anna Kaplan

Mentor: Steve Townsend
Home Institution: Bowdoin College
Research Title: "Synthesis of the Tumor Associated Carbohydrate Antigen GD2"

Abstract:
A goal of cancer immunotherapy is to use the body’s own immune system to recognize cancer cells and attack them. One way that cancer cells can be distinguished from normal cells is by the presence of tumor associated carbohydrate antigens (TACAs). If presented to the immune system properly, the TACA should evoke an immune response to signal selective eradication of the cancer cells expressing the specific glycosylation pattern. One TACA expressed on the surface of multiple high-risk cancer cell types is GD2. Due to the interest of using GD2 as an antigen in cancer immunotherapy treatments, a large quantity of the TACA is needed for immunological studies. It is not feasible to obtain them directly from cancer cells, making chemical synthesis the next best alternative. The goal of this project is to work towards the total synthesis of GD2.

Armin Nourani

Mentor: David Wright
Home Institution: University of Texas-Austin
Research Title: "Investigation into Methods of Disassociating Native HRP2-Immunocomplexes for Enhanced Detection in Malaria Diagnostics"

Abstract:
Histidine-Rich Protein II (HRP2) is a malarial biomarker that is found in blood samples of individuals infected with the Plasmodium falciparum parasite. In developing countries, rapid diagnostic tests (RDTs) are frequently employed to detect free-HRP2 for diagnosis of malaria in a point-of-care setting. Much like a standard pregnancy test, malarial RDTs are capable of initially capturing and collecting HRP2 colored gold nanoparticle-conjugated antibodies found on the sample-loading pad. Through lateral flow, this complex is then allowed to travel down a test strip where a secondary antibody is capable of binding and concentrating the complex, forming a visual test-line that ultimately indicates the presence of P. falciparum. Individuals with frequent exposure to the P. falciparum parasite can endogenously begin producing native antibodies against HRP2. These internal antibodies occupy potential binding sites on HRP2, thereby decreasing the number of binding opportunities for diagnostic antibodies when a blood sample is loaded onto an RDT. Thus, false-negative readings are frequently encountered. Currently, we are investigating and optimizing methods of sample pre-processing that would be effective means of disassociating native HRP2-immunocomplexes prior to RDT readings. Significant RDT signal enhancement has been observed from both a high heat treatment and a chemical denaturant treatment with low heating. These results indicate potential avenues to improving malaria diagnostics but require further analysis to determine the best disassociation techniques for downstream incorporation into a blood sample-processing device that is advantageous for use in low-resource settings.

Megan Schoenberger

Mentor: Tina Iverson
Home Institution: St. John's University
Research Title: "Can Arrestin-2 Be Activated by the Small Molecule Inositol Hexakisphosphate?"

Abstract:
Arrestins are a family of proteins that serve as central regulators in G protein coupled receptor signaling, pathways that control various important processes throughout the cell. Arrestins can act by directly binding G protein coupled receptors or by scaffolding proteins in downstream signaling. The downstream signaling activity may be regulated by either small molecules, for example inositol hexakisphosphate (IP₆), or by binding to receptors. Intriguingly, IP₆-activated arrestin-3, but not the highly similar isoform arrestin-2, is able to activate the mitogen activated protein (MAP) kinase Jun-N-terminal kinase-3 (JNK-3). The crystal structure of arrestin-3 in complex with IP₆ shows that arrestin-3 undergoes a large conformational change and adopts an active form when bound to this small molecule, such that it is poised for MAP kinase and JNK-3 binding. I aim to determine the crystal structure of arrestin-2 in the presence of IP₆, using X-ray crystallography. The results are expected to show how the structure of arrestin-2 is influenced by IP₆. Comparison of the arrestin-2-IP₆ and arrestin-3-IP₆ structure will help identify key structural elements critical for downstream scaffolding.

Nathan Winters

G protein-gated inward-rectifying potassium (GIRK) channels mediate resting membrane potential and their activation decreases cellular excitability. The activity of these channels is enhanced following agonist binding to G protein-coupled receptors (GPCRs) of the G_i/o subtype. The βγ complex of these heterotrimeric G proteins binds to GIRK and promotes channel opening. As a method of signal regulation, many GPCRs undergo clathrin-mediated endocytosis as a mechanism of acute desensitization. We seek to address whether GIRK channels internalize with their corresponding GPCR as a complex, or if the GPCR internalizes independent of GIRK. Should GIRKs be internalized alongside GPCRs, this could have implications regarding the acute desensitization and tolerance to drugs that act as GPCR agonists, such as opioids. If GIRK internalizes with the GPCR, we hypothesize this acute desensitization of GIRK can be bypassed via direct channel activation by recently discovered small molecule GIRK activators. 

Jessica Zinna

Halocyclizations are a class of reactions that have gained interest in recent years. The ability to synthesize complex heterocycles enantioselectively using relatively simple reagents in a one-pot reaction mixture is enormously beneficial for the advancement of chemical synthesis. The majority of previous studies have focused on intramolecular reactions; the current work focuses on an intermolecular capture of an electrophile followed by an intramolecular cyclization. Achieving high enantioselectivity is possible through the use of a dual Brønsted acid/Brønsted base organocatalyst that has the ability to stabilize the reactive intermediate. Described is a novel synthetic route to cyclic carbamates utilizing a homoallylic alcohol, an isocyanate, and an iodine source in the presence of a previously described organic catalyst. Future work will focus on the development and utilization of chiral HPLC to determine the enantioselectivity of the reactions performed.