Spotlights-Research at the CBI

Joy Thames

As outbreaks of new viruses occur, the need for broad spectrum antiviral drugs has increased. In that regard, nucleos(t)ide analogues have a rich history as antivirals. One modification in nucleoside drug design that has proven successful is the use of acyclic sugars, such as that found in Acyclovir (ACV), an FDA-approved drug for herpes simplex virus. Research in the Seley-Radtke group has focused on the development of novel nucleos(t)ide analogues known as “fleximers”, which feature a “split” purine nucleobase, where a carbon-carbon single bond connects the pyrimidine and imidazole rings, thus introducing flexibility to the nucleobase scaffold. This endows the “fleximers” with potent activity not seen for the corresponding rigid analogues. Combining the flex-nucleobase with the acyclic sugar of ACV produced a series of doubly flexible Flex-ACV analogues. These novel analogues have exhibited low micromolar to nanomolar levels of activity against human coronaviruses (SARS-CoV-1, MERS, HuCoV-NL63) as well as Ebola, Yellow Fever, Dengue and TBEV, while ACV has no activity against those viruses. My project has focused on the design and synthesis of new Flex-ACV analogues, as well as the optimization of previously synthesized analogues for antiviral testing and mechanism of action studies. Recently Flex-ACV analogues have shown mid-micromolar activity against SARS-CoV-2. The biological window of the Flex-ACV compounds continues to be investigated, along with new fleximer analogues of cidofovir. Cidofovir is an FDA approved nucleoside drug for cytomegalovirus retinitis in aids patients and its lipid prodrug analogue Brincidofovir has exhibited activity against Ebola. Using modern synthetic methods I have been able to begin the synthesis of cidofovir analogues, as well as the synthesis of new Flex-ACV analogues.

John Terrell

Zach Nichols

1. Nichols, Z. E.; Saha, L.; Knoblauch, R.; Santaus, T. M.; Geddes, C. D. “Development of a Microplate Platform for High-Throughput Sample Preparation Based on Microwave Metasurfaces”
   IEEE Access. 2021, 9, 37823-37833.
2. Nichols, Z. E.; Geddes, C. D. “Sample Preparation and Diagnostic Methods for a Variety of Settings: A Comprehensive Review” Molecules. 2021, 26 (18), 5666.
3. Nichols, Z. E.; Geddes, C.D. Applying Metasurfaces to Biological Sample Preparation and Clinical Diagnosis. 2022 UMBC Graduate Research Conference. University of Maryland, Baltimore County. Baltimore, Maryland. March 2022. (Poster)

Christopher Goodis

The growth of tumor cells has been heavily linked to the hijacking of intrinsic apoptotic pathways. This involves the upregulation of several proteins to circumvent programmed cell death. The Bcl-2 family of proteins are instrumental in the apoptotic pathway found within cell mitochondria. Cancer cells can upregulate Bcl-2 anti-apoptotic proteins to sequester pro-apoptotic proteins which promotes tumor growth. Bcl-2, Bcl-xL, and Mcl-1 are all examples of these upregulated proteins. Most studies focused on the discovery of inhibitors to these proteins utilize the alpha-helical pro-apoptotic proteins as a starting point. While there have been extensive studies on these proteins, anti-apoptotic protein BFL-1 has received less attention despite evidence showing that certain cancers such as melanomas, leukemias, and lymphomas are dependent on BFL-1 upregulation. Most inhibitors target the binding groove found within the anti-apoptotic proteins which comes with it a unique set of challenges. To accelerate the design of a potent BFL-1 inhibitor, we will also be utilizing the unique Cys55 found within the binding grove of BFL-1 by incorporating a covalent warhead to increase affinity of our compound. Utilizing the findings of previously validated BH3 mimetics, computer-aided drug design (CADD), and virtual high-throughput fragment screening, my research aims to modify these mimetics to further selectivity towards BFL-1 as well as deliberately position warheads to react with Cys55. Utilizing cell data, molecular modeling, and mass spec analysis, we will undergo an iterative approach with our compounds to optimize their ability to inhibit BFL-1.

Notable publications and presentations:

1. Goodis, C.C., Chan, A., Pommier, E., Fletcher, S. Recent Application of Covalent Chemistries in Protein-Protein Interaction Inhibitors. RSC Medicinal Chemistry, 2022, 13, 921-928. (*co-first authors)
2. Goodis, C.C., Drennen, B., Bowen, N., Yu, W., Vickers, G., Wilder, P., Mackerell, A.D., Fletcher, S. Scaffold Hopping from Indoles to Indazoles Yields Dual MCL-1 / BCL-2 Inhibitors from MCL-1 Selective Leads. RSC Medicinal Chemistry, 2022, 13, 963-969. (*co-first authors)
3. Truong, N., Goodis, C.C., Cottingham, A.L., Shaw, J.R., Fletcher, S., Pearson, R.M. Modified Suberoylanilide Hydroxamic Acid Reduced Drug Associated Immune Cell Death and Organ Damage under Lipopolysaccharide Inflammatory Challenge. ACS Pharmacol. Transl. Sci., 2022, 5, 11, 1128–1141.
4. Goodis, C.C., Wenbo, Y., Lowe, B.D., MacKerell, A.D., Fletcher, S. Discovery of Novel BFL-1 Inhibitors by CADD and Screening an In-House Library of Synthetic BH3 Mimetics. Graduate Research Conference, Oral Presentation. University of Maryland, Baltimore, Baltimore, MD; March 2023.
5. Goodis, C.C., Wenbo, Y., Lowe, B.D., MacKerell, A.D., Fletcher, S. Discovery of Novel BFL-1 Inhibitors by Computer-Aided Drug Design and Screening an In-House Library of Synthetic Alpha-Helix Mimetics. ACS Spring 2023: Crossroads of Chemistry, Poster Presentation. Indianapolis Convention Center, Indianapolis, IN; March 2023.

Mark Lee

Across all bacteria, the ferrous iron (Fe²⁺) uptake (Feo) system is the most prevalent and the most well-distributed system dedicated to the acquisition of Fe²⁺. However, despite Feo’s nearly ubiquitous presence across the prokaryotic domain, this system remains poorly understood. The Feo system consists canonically of three proteins: FeoA, FeoB, and FeoC. FeoB is a complex, transmembrane G protein and is arguably the most important component of the Feo system. The function of FeoB is to transport iron across a lipid bilayer to within the cytosol, but the structural and mechanistic details of this process are lacking. My research focuses on the incorporation of FeoB into lipid-protein and copolymer nanodiscs for functional and structural characterizations of FeoB. In addition, recent studies have suggested that not all FeoBs are GTP-specific, but rather may be NTPases. To probe this hypothesis, I am working to determine the structure of the N-terminal domain of FeoB (NFeoB) in the presence of adenosine nucleotides. Finally, recent bioinformatics data from my lab have identified genes encoding a small transmembrane protein (designated FeoD) of unknown function adjacent to FeoB in the feo operon. This protein is predicted to bear a single transmembrane helix with a C-terminal cysteine-rich tail. Because FeoD is present in many bacterial genomes that lack FeoC (a soluble, [Fe-S] cluster-binding protein) I predict that FeoD may function similarly. Thus, I am also working to clone, to express, to purify, and to characterize (structurally and functionally) the newly-discovered FeoD protein. Combined, this work helps elucidate the mechanistic details of this essential iron acquisition pathway.

Notable publications and presentations:

1. Brown, J. B.; Lee, M. A.; and Smith, A. T. The structure of Vibrio cholerae FeoC reveals conservation of the helix-turn-helix motif but not the cluster-binding domain. bioRxiv. 2022, DOI: 10.1101/2022.02.26.482101
2. Sestok, A. E.; Lee, M. A.; and Smith, A. T. Prokaryotic ferrous iron uptake: exploiting pools of reduced iron across multiple microbial environments. In: Hurst, C.J. (eds) Microbial Metabolism of Metals and Metalloids. Advances in Environmental Microbiology,2022, 10, 299-357. Springer, Cham.
3. Brown JB, Lee MA, Smith AT. Ins and Outs: Recent Advancements in Membrane Protein-Mediated Prokaryotic Ferrous Iron Transport. Biochemistry. 2021 Nov 9;60(44):3277-3291.