Biochemistry, Biophysics, and Structural Biology Commons^™

Ppgpp And Rna-Polymerase Backtracking Guide Antibiotic-Induced Mutable Gambler Cells, Yin Zhai, P J Minnick, John P Pribis, Libertad Garcia-Villada, P J Hastings, Christophe Herman, Susan M Rosenberg

Faculty, Staff and Students Publications

Antibiotic resistance is a global health threat and often results from new mutations. Antibiotics can induce mutations via mechanisms activated by stress responses, which both reveal environmental cues of mutagenesis and are weak links in mutagenesis networks. Network inhibition could slow the evolution of resistance during antibiotic therapies. Despite its pivotal importance, few identities and fewer functions of stress responses in mutagenesis are clear. Here, we identify the Escherichia coli stringent starvation response in fluoroquinolone-antibiotic ciprofloxacin-induced mutagenesis. Binding of response-activator ppGpp to RNA polymerase (RNAP) at two sites leads to an antibiotic-induced mutable gambler-cell subpopulation. Each activates a stress response …

Dpc29 Promotes Post-Initiation Mitochondrial Translation In Saccharomyces Cerevisiae, Kyle A. Hubble, Michael F. Henry

Rowan-Virtua School of Osteopathic Medicine Departmental Research

Mitochondrial ribosomes synthesize essential components of the oxidative phosphorylation (OXPHOS) system in a tightly regulated process. In the yeast Saccharomyces cerevisiae, mitochondrial mRNAs require specific translational activators, which orchestrate protein synthesis by recognition of their target gene's 5'-untranslated region (UTR). Most of these yeast genes lack orthologues in mammals, and only one such gene-specific translational activator has been proposed in humans-TACO1. The mechanism by which TACO1 acts is unclear because mammalian mitochondrial mRNAs do not have significant 5'-UTRs, and therefore must promote translation by alternative mechanisms. In this study, we examined the role of the TACO1 orthologue in yeast. We …

Discovery Of Highly Potent And Bmpr2-Selective Kinase Inhibitors Using Dna-Encoded Chemical Library Screening, Ram K Modukuri, Diana Monsivais, Feng Li, Murugesan Palaniappan, Kurt M Bohren, Zhi Tan, Angela F Ku, Yong Wang, Chandrashekhar Madasu, Jian-Yuan Li, Suni Tang, Gabriella Miklossy, Stephen S Palmer, Damian W Young, Martin M Matzuk

Faculty, Staff and Students Publications

The discovery of monokinase-selective inhibitors for patients is challenging because the 500+ kinases encoded by the human genome share highly conserved catalytic domains. Until now, no selective inhibitors unique for a single transforming growth factor β (TGFβ) family transmembrane receptor kinase, including bone morphogenetic protein receptor type 2 (BMPR2), have been reported. This dearth of receptor-specific kinase inhibitors hinders therapeutic options for skeletal defects and cancer as a result of an overactivated BMP signaling pathway. By screening 4.17 billion “unbiased” and “kinase-biased” DNA-encoded chemical library molecules, we identified hits CDD-1115 and CDD-1431, respectively, that were low-nanomolar selective kinase inhibitors of …

Probing Amyloid-Beta Protein Structure And Dynamics With A Selective Antibody, Shikha Grover

Dissertations

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder. The AD brain is characterized by significant neuronal loss and accumulation of insoluble fibrillar amyloid-β protein (Aβ) plaques and tau protein neurofibrillary tangles in the brain. However, over the last decade, many studies have shown that the neurodegenerative effect of Aβ may in fact be caused by various soluble oligomeric forms as opposed to the insoluble fibrils. Furthermore, the data suggest that a pre-fibrillar aggregated form, termed protofibrils, mediates direct neurotoxicity, and triggers a robust neuroinflammatory response.

Antibodies targeting the various conformation of Aβ are important therapeutic agents to prevent the progression …

Synthetic Assembly Dna Cloning To Build Plasmids For Multiplexed Transgenic Selection, Counterselection Or Any Other Genetic Strategies Using Drosophila Melanogaster, Koen J T Venken, Nick Matinyan, Yezabel Gonzalez, Alejandro Sarrion-Perdigones, Herman A Dierick

Faculty, Staff and Students Publications

We recently described a drug-based selectable and counterselectable genetic platform for the animal model system Drosophila melanogaster, consisting of four resistance and two sensitivity markers that allow direct selection for, or counterselection against, a desired genotype. This platform eliminates the need to identify modified progeny by traditional laborious screening using dominant eye and body color markers, white⁺ and yellow⁺, respectively. The four resistance markers permit selection of animals using G418 sulfate, Puromycin HCl, Blasticidin S, or Hygromycin B, while the two sensitivity markers allow counterselection of animals against Ganciclovir or Acyclovir, and 5-Fluorocytosine. The six markers …

Serial Recombineering Cloning To Build Selectable And Tagged Genomic P[Acman] Bac Clones For Selection Transgenesis And Functional Gene Analysis Using Drosophila Melanogaste, Koen J T Venken, Nick Matinyan, Yezabel Gonzalez, Herman A Dierick

Faculty, Staff and Students Publications

Transgenes with genomic DNA fragments that encompass genes of interest are the gold standard for complementing null alleles in rescue experiments in the fruit fly Drosophila melanogaster. Of particular interest are genomic DNA clones available as bacterial artificial chromosomes (BACs) or fosmids from publicly available genomic DNA libraries. Genes contained within BAC and fosmid clones can be easily modified by recombineering cloning to insert peptide or protein tags to localize, visualize, or manipulate gene products, and to create point mutations or deletions for structure-function analysis of the inserted genes. However, since transgenesis efficiency is inversely correlated with transgene size, obtaining …

Impact Of Sample Conditions On Dna Phosphodiester Backbone Bi/Bii Conformational Equilibrium Dynamics, Autumn C. Pilarski

Graduate Theses/Dissertations

DNA damage, such as single base lesions and mismatches, is highly prevalent within cells. If these DNA damage events are not repaired, they could lead to mutations and thus disease and cancer. Intricate repair mechanisms are in place to fix these damage events, one such being Base Excision Repair (BER) and associated enzyme: Thymine DNA Glycosylase (TDG). The first step of this repair process, recognition of the lesion by TDG, is not well understood. The following thesis presents results to better understand the fundamental biophysical question of how a DNA lesion within a mismatch context is recognized in a million …

Functional Characterization Of The Newly Discovered Type V Crispr-Cas Protein Cas12a2, Dylan J. Keiser

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Similarly to people, bacteria are under the treat of infection by viruses. To circumvent these threats, bacteria evolve complex immune systems. Our understanding of some of these immune systems has led to many advancements in the field of Biotechnology including tools that made expressing proteins for study in a lab easier, tools that revolutionized the feasibility of gene editing, and tools that could change the way we think about viral diagnostics and cancer therapeutics. A certain type of immune system that bacteria use to fight virus is called a CRISPR system. Presented here is work to understand the function of …

Control Of Ribosomal Rna Synthesis By Hematopoietic Transcription Factors, Charles Antony, Subin S George, Justin Blum, Patrick Somers, Chelsea L Thorsheim, Dexter J Wu-Corts, Yuxi Ai, Long Gao, Kaosheng Lv, Michel G Tremblay, Tom Moss, Kai Tan, Jeremy E Wilusz, Austen R D Ganley, Maxim Pimkin, Vikram R Paralkar

Faculty, Staff and Students Publications

Ribosomal RNAs (rRNAs) are the most abundant cellular RNAs, and their synthesis from rDNA repeats by RNA polymerase I accounts for the bulk of all transcription. Despite substantial variation in rRNA transcription rates across cell types, little is known about cell-type-specific factors that bind rDNA and regulate rRNA transcription to meet tissue-specific needs. Using hematopoiesis as a model system, we mapped about 2,200 ChIP-seq datasets for 250 transcription factors (TFs) and chromatin proteins to human and mouse rDNA and identified robust binding of multiple TF families to canonical TF motifs on rDNA. Using a 47S-FISH-Flow assay developed for nascent rRNA …

Expression And Purification Of E. Coli Yoaa, A Putative Helicase, Mark Gregory, Vincent Sutera Mr., Susan Lovett Dr.

Medical Student Research Symposium

All cells must maintain their genomic integrity to survive, which they achieve through several repair mechanisms that necessitate unwinding the damaged DNA by helicases. In Escherichia coli (E. coli), YoaA has been genetically shown to be involved in DNA repair and shares conserved sequences with helicase DinG. The goal of our study was to purify YoaA for further biochemical characterization. For expression, YoaA was fused to a His tag and overexpressed in MG1655 E.coli under the lacZ or T7 promoters for 2 hours, 4 hours, or overnight at 24oC, 30oC or 37oC. For purification, crude lysate was applied to a …

Targeting Aberrant Replication And Dna Repair Events For Treating Breast Cancers, Subapriya Rajamanickam, Jun Hyoung Park, Panneerdoss Subbarayalu, Santosh Timilsina, Kaitlyn Bates, Pooja Yadav, Saif S R Nirzhor, Vijay Eedunuri, Tabrez A Mohammad, Kwang Hwa Jung, Benjamin Onyeagucha, Nourhan Abdelfattah, Raymond Benevides, Grace Lee, Yidong Chen, Ratna Vadlamudi, Andrew Brenner, Virginia Kaklamani, Ismail Jatoi, John Kuhn, Robert Hromas, Yogesh K Gupta, Benny A Kaipparettu, Jack L Arbiser, Manjeet K Rao

Faculty, Staff and Students Publications

The major limitations of DNA-targeting chemotherapy drugs include life-threatening toxicity, acquired resistance and occurrence of secondary cancers. Here, we report a small molecule, Carbazole Blue (CB), that binds to DNA and inhibits cancer growth and metastasis by targeting DNA-related processes that tumor cells use but not the normal cells. We show that CB inhibits the expression of pro-tumorigenic genes that promote unchecked replication and aberrant DNA repair that cancer cells get addicted to survive. In contrast to chemotherapy drugs, systemic delivery of CB suppressed breast cancer growth and metastasis with no toxicity in pre-clinical mouse models. Using PDX and ex …

The Effects Of Crowding Agents On The Pka Of Physiologically Stable I-Motif Dna, Courtney Turner

Honors Theses

The overall goal of this thesis was to investigate the environmental conditions that induce i-Motif folding of the DNA strand DUX4L22, a cytosine-rich segment of DNA found in the human genome. Cellular conditions were simulated using sodium cacodylate buffer and multiple weights of polyethylene glycol as a crowding agent. The presence of i-motifs were confirmed by Circular Dichroism spectroscopy. I found that DUX4L22 does form i-motifs under these physiological simulations at both acidic and neutral pHs. DUX4L22 therefore shows potential for use in studies of a wide variety of biotechnological advances, such as regulatory switches in nanomachines or drug-delivery systems.

Bci Validation: Yfiler Plus Kit Validation, Chloe Koon

Honors Projects

In order to have access and use the Combined DNA Index System (CODIS), it is required by the Federal Bureau of Investigation's Quality Assurance Standards (FBI-QAS) for Forensic DNA Units to complete comprehensive validation studies on all equipment, materials, and methods used in the process of DNA analysis. This study continues validation previous done within the Ohio Bureau of Criminal Investigation (BCI). YFiler Plus is a DNA amplification kit that is used in cases where it is most useful to examine only male DNA profile(s) within a sample by amplifying loci only on the Y-Chromosome. Components of this study include …

Generating A Colorimetric Ssa4 Transcript Export Reporter For Multicopy Suppression Screen In S. Cerevisiae, Zaid Hatem

[Archive] Belmont University Research Symposium (BURS)

The export of mRNA from the nucleus to the cytoplasm is a regulatory point that is essential to the pathway of gene expression in eukaryotic cells. The export of mRNA transcripts is mediated through selective doorways called the nuclear pore complexes (NPC). Additionally, there are proteins associated with the nuclear pore complex that assist in facilitating the export. This includes association with the export receptor, Mex67, which binds to the transcript and ferries it through NPCs. During cellular stress, such as heat shock, the export of housekeeping mRNA transcripts is halted, forcing these transcripts to remain inside the nucleus and …

Test-Driving The Next Generation Of Crispr Gene Editing, Olivia Gornichec, Kailey Mayer

Research on Capitol Hill

USU team Kailey, recent graduate of animal science, and Olivia, senior in biochemistry, have led and funded this project through a student grant. CRISPR has been making waves in the scientific community for its potential to help us edit genomes. However, that is just one of the known types of CRISPR, and other types aren’t in forms that are accessible to study. Kailey and Olivia have successfully cloned Type IV-B into a plasmid that can now be used to perform further research into what this system does. The two students never expected that, as undergrads, they would make a foundation-level …

Synthetic Assembly Dna Cloning Of Multiplex Hextuple Luciferase Reporter Plasmids, Alejandro Sarrion-Perdigones, Yezabel Gonzalez, Koen J T Venken

Faculty, Staff and Students Publications

Multiplex hextuple luciferase assaying allows monitoring the activity of five experimental pathways against one control at the same time. To perform multiplex hextuple luciferase assaying, six orthogonal luciferase reporter units are needed of which five are pathway-specific and one acts as a control for normalization. To ensure stoichiometric delivery of all six luciferase reporters in every transfected cell, synthetic assembly DNA cloning is used to stitch together all six luciferase reporter units into a single vector. Here, we provide a detailed three-step synthetic assembly DNA protocol to generate multiplex hextuple luciferase reporter plasmids for any five cellular signaling pathways of …

Reproducibility Of Individual Dna Deposits Detected Through Cellular Fluorescence, Natalee Small-Davidson

Student Theses

Contact traces are an important part of DNA casework, but the probative value of any identified associations depends on the possibility of passive transfer. There is known individual variation in DNA left behind during contact, this DNA shedding propensity has an effect on whose DNA is detected. This study evaluated this variability using a cell staining approach. Volunteers were asked to deposit a fingerprint on a clean glass slide, then wash their hands and deposit a second fingerprint after a 30-minute wait without touching anything. Three sets of samples were collected over three consecutive weeks. Fingerprints were stained with a …

Supercoiling And Looping Promote Dna Base Accessibility And Coordination Among Distant Sites, Jonathan M Fogg, Allison K Judge, Erik Stricker, Hilda L Chan, Lynn Zechiedrich

Faculty, Staff and Students Publications

DNA in cells is supercoiled and constrained into loops and this supercoiling and looping influence every aspect of DNA activity. We show here that negative supercoiling transmits mechanical stress along the DNA backbone to disrupt base pairing at specific distant sites. Cooperativity among distant sites localizes certain sequences to superhelical apices. Base pair disruption allows sharp bending at superhelical apices, which facilitates DNA writhing to relieve torsional strain. The coupling of these processes may help prevent extensive denaturation associated with genomic instability. Our results provide a model for how DNA can form short loops, which are required for many essential …

Investigating Factors That Affect Hiv-1 Capsid Stability, Max Mao, Joshua Temple

The Yale Undergraduate Research Journal

TKH HIV caSVLd, a SURWHLQ VKHOO cRPSRVHd RI PRQRPHULc XQLWV RI CA, IRUPV a IXOOHUHQH cRQH WKaW SURWHcWV HIV¶V YLUaO JHQRPH aQd enzymes during infection. I am interested in elucidating the factors that influence stability of the capsid shell and capturing the structural interactions between HIV capsid, host restriction factors, and small molecules using biochemical and structural biology techniques. HIV capsid shell was broken down and purified into hexamer and pentamer units for in vitro study. Structural assays were performed using X-ray crystallography and biochemical analysis was performed using pelleting assays. By understanding capsid structure with factors that confer stability, …

Two Mechanisms Of Chromosome Fragility At Replication-Termination Sites In Bacteria, Qian Mei, Devon M Fitzgerald, Jingjing Liu, Jun Xia, John P Pribis, Yin Zhai, Ralf B Nehring, Jacob Paiano, Heyuan Li, Andre Nussenzweig, P J Hastings, Susan M Rosenberg

Faculty, Staff and Students Publications

Chromosomal fragile sites are implicated in promoting genome instability, which drives cancers and neurological diseases. Yet, the causes and mechanisms of chromosome fragility remain speculative. Here, we identify three spontaneous fragile sites in the Escherichia coli genome and define their DNA damage and repair intermediates at high resolution. We find that all three sites, all in the region of replication termination, display recurrent four-way DNA or Holliday junctions (HJs) and recurrent DNA breaks. Homology-directed double-strand break repair generates the recurrent HJs at all of these sites; however, distinct mechanisms of DNA breakage are implicated: replication fork collapse at natural replication …

Analysis Of Foki Cleavage Resistance Observed In Dna Sequences Generated Via The Combinatorial Selection Method, Repsa, Andre Berry

Master of Science in Chemical Sciences Theses

FokI is a thoroughly investigated and highly utilized restriction endonuclease that recognizes the DNA sequence, 5’-GGATG-3’, and cleaves outside of this site 9 and 13 base-pairs downstream. The shifted cleavage function possessed by this kind of endonuclease is utilized in many applications including the combinatorial selection method, REPSA. FokI employment in the REPSA procedure has demonstrated the tendency to select for an unmodified sequence that possesses the recognition site yet is refractory to cleavage by the enzyme. Sequencing of the cleavage resistant DNA has revealed the inhibitory event to be induced by the presence of an additional inversely oriented recognition …

Replication Protein A (Rpa) Targeting Of Uracil Dna Glycosylase (Ung2), Derek Chen, Brian P Weiser

Rowan-Virtua Research Day

Replication Protein A (RPA) is a single stranded DNA binding protein which stabilizes ssDNA for replication and repair. One function of RPA is to bind the DNA repair enzyme uracil DNA glycosylase (UNG2) and direct its activity towards ssDNA dsDNA junctions.

UNG2 removes uracil bases from DNA which can appear through dUMP misincorporation or through cytosine deamination. If uracil is present instead of a cytosine, then the original GC pair becomes a GU pair. The uracil will then base pair to adenine in the replicated daughter strand. This results in a GC → AT mutation that could contribute to cancer …

Chemical And Co-Solute Effects Of Polyethylene Glycol On I-Motif Formation, Lindsey Rutherford

Honors Theses

DNA typically forms Watson and Crick double helix structures in which adenine, thymine, guanine, and cytosine pair with their complimentary DNA base. However, DNA i-motif structures can form in cytosine rich DNA, typically under slightly acidic conditions (~pH 6). DNA i-motifs are four stranded secondary structures in which cytosine pairs with cytosine to form a quadruplex. The i-motifs are typically formed in acidic conditions because of the protonation in the C•C base pair between one of the three hydrogen bases. Recent studies have suggested i-motifs can also form under neutral conditions, which is more realistic for a cell. It is …

Effects Of Crowding Agents On I-Motif Dna, Hayden Brines

Honors Theses

Deoxyribonucleic acid (DNA) is a well-known double stranded, helical, biological molecule. In addition to its more commonly known structure, DNA can also form more complicated structures like G-quadruplexes and i-motifs (iM). The iMs are formed by cytosine rich DNA and are a four stranded structure that is typically looped around itself. The iM formation is typically pH-dependent and is favored in more acidic conditions; the pKa value is approximately 6.5. This pKa value allows for potential in vivo formation, since the cells have a pH of approximately 7.3. Due to this, iMs are thought to be powerful, innovative molecules for …

Nucleic Acids Promote Oligomerization Of Immunoglobulin G, Alexa Gomez

Electronic Theses and Dissertations

Nucleic acids have been found to prevent aggregation as chaperones, as well as act as co-factors and promote aggregation of amyloidogenic proteins leading to various diseases. Immunoglobulin G, IgG, are prone to aggregate as therapeutic proteins, and light chains of IgG can form amyloid fibrils, causing a disease known as light chain amyloidosis. Here we discuss the effect nucleic acids have on full-length immunoglobulin G aggregation. Our results show G-quadruplex DNA, and bulk DNA lead to oligomerization of full-length IgG, and induce increases in secondary structure. Tryptophan fluorescence indicates structural changes are occurring in the presence of DNA. Additionally, IgG …

Development Of A Dna Biosensor Using Crispr/Dcas9 On A Graphene Oxide Surface For Detecting Antibiotic Resistance Genes, Wendy Cecil

Mahurin Honors College Capstone Experience/Thesis Projects

Antibiotic resistance is a rapidly spreading global threat to human health. Previously in our lab, we developed a simple method for facile detection of antibiotic resistance genes (ARGs) in bacteria. This DNA detection system takes advantage of the CRISPR-Cas system (Clustered Regularly Interspaced Short Palindromic Repeat and CRISPRAssociated Protein). We designed CRISPR in complex with nuclease deactivated Cas9 (dCas9) on graphene oxide (GO) sheets conjugated with Cas9 antibodies. Single guide RNA (sgRNA) was customized to program dCas9 for target DNA binding. sgRNA was covalently labeled with fluorescein to provide fluorescence signal. Graphene oxide (GO) is utilized for its quenching properties …

Rapid Induction Of The Unfolded Protein Response And Apoptosis By Estrogen Mimic Ttc-352 For The Treatment Of Endocrine-Resistant Breast Cancer, Balkees Abderrahman, Philipp Y Maximov, Ramona F Curpan, Sean W Fanning, Jay S Hanspal, Ping Fan, Charles E Foulds, Yue Chen, Anna Malovannaya, Antrix Jain, Rui Xiong, Geoffrey L Greene, Debra A Tonetti, Gregory R J Thatcher, V Craig Jordan

Faculty, Staff and Students Publications

Patients with long-term estrogen-deprived breast cancer (BC), after resistance to tamoxifen or aromatase inhibitors develops, can experience tumor regression when treated with estrogens. Estrogen’s anti-tumor effect is attributed to apoptosis via the estrogen receptor (ER). Estrogen treatment can have unpleasant gynecological and non-gynecological adverse events thus the development of safer estrogenic agents remains a clinical priority. Here, we study synthetic selective estrogen mimics (SEMs) BMI-135 and TTC-352, and the naturally-occurring estrogen estetrol (E4), which are proposed as safer estrogenic agents compared to 17β-estradiol (E2), for the treatment of endocrine-resistant BC. TTC-352 and E4 are being evaluated in BC clinical trials. …

Genomic Mapping Of Dna-Repair Reaction Intermediates In Living Cells With Engineered Dna Structure-Trap Proteins, Jingjing Liu, Qian Mei, Sadeieh Nimer, Devon M Fitzgerald, Susan M Rosenberg

Faculty, Staff and Students Publications

Diverse DNA structures occur as reaction intermediates in various DNA-damage and -repair mechanisms, most of which results from replication stress. We harness the power of proteins evolutionarily optimized to bind and "trap" specific DNA reaction-intermediate structures, to quantify the structures, and discern the mechanisms of their occurrence in cells. The engineered proteins also allow genomic mapping of sites at which specific DNA structures occur preferentially, using a structure-trapping protein and ChIP-seq- or Cut-and-Tag-like methods. Genome-wide identification of sites with recurrent DNA-damage intermediates has illuminated mechanisms implicated in genome instability, replication stress, and chromosome fragility. Here, we describe X-seq, for identifying …

Quantifying Anticancer Drug Doxorubicin Binding To Dna Using Optical Tweezers, Zachary Ells

Honors Program Theses and Projects

Doxorubicin is a successful anticancer drug approved for use in the 1970s and is considered to be one of the most effective cancer treatment methods today. Although Doxorubicin has positive survival statistics it has very negative side effects in many cases. Bleeding from the soles of the palms and feet, along with excruciating pain is often exhibited through the administration of this drug. Based on the preliminary findings utilizing optical tweezers we anticipate that this study will provide critical information about the drug binding mechanism. Single molecule biophysics techniques have provided useful insight into the DNA-binding mechanisms of small molecules. …

Structural Characterization And Selective Drug Targeting Of Higher-Order Dna G-Quadruplex Systems., Robert Chandos Monsen

Electronic Theses and Dissertations

There is now substantial evidence that guanine-rich regions of DNA form non-B DNA structures known as G-quadruplexes in cells. G-quadruplexes (G4s) are tetraplex DNA structures that form amid four runs of guanines which are stabilized via Hoogsteen hydrogen bonding to form stacked tetrads. DNA G4s have roles in key genomic functions such as regulating gene expression, replication, and telomere homeostasis. Because of their apparent role in disease, G4s are now viewed as important molecular targets for anticancer therapeutics. To date, the structures of many important G4 systems have been solved by NMR or X-ray crystallographic techniques. Small molecules developed to …