Semester of Graduation
Spring 2026
Degree Type
Thesis
Degree Name
Master of Science in Integrative Biology (MSIB)
Department
Molecular and Cellular Biology (MCB)
Committee Chair/First Advisor
Dr. Soon Goo Lee and Dr. Masafumi Yoshinaga
Second Advisor
Dr. Mohammad A. Halim
Third Advisor
Dr. Md Masud Rana
Abstract
This study explores peptide-based strategies to combat infectious diseases through two complementary approaches: the discovery of arsenic-containing ribosomally synthesized and posttranslationally modified peptides (AsRiPPs) as an antibiotic, and the design of peptide inhibitors targeting phosphoethanolamine methyltransferase (PMT) for antiparasitic drug development. In the first project, genome mining identified a unique arsM-containing biosynthetic gene cluster in Microbispora rosea, suggesting the production of previously uncharacterized arsenic-containing RiPPs. Culturing of the native organism supplemented with arsenite followed by LC-ICP-MS analysis confirmed the formation of methylated arsenic-containing compounds. Purification using lyophilization and gel-filtration chromatography yielded fractions exhibiting approximately 40% growth inhibition against Escherichia coli, indicating antimicrobial activity. Heterologous expression of biosynthetic genes in E. coli further validated the roles of key enzymes, including MrArsM, supporting a proposed biosynthetic pathway for AsRiPP formation. The second project focused on the characterization of CePMT2 from Caenorhabditis elegans, a key enzyme in phosphatidylcholine biosynthesis and a promising antiparasitic drug target absent in humans. Structural determination via X-ray crystallography, combined with mutagenesis and enzyme assay, identified critical residues involved in catalysis. Computational peptide screening, molecular docking, and molecular dynamics simulations led to the identification of promising peptide candidates. Selected peptides were synthesized and evaluated using ITC and MST, confirming their binding with CePMT2. This work highlights the potential of arsenic-containing RiPPs as a new class of antibiotics and demonstrates the feasibility of peptide-based inhibition of PMT enzymes, contributing to the development of novel therapeutics against antibiotic-resistant bacteria and parasitic diseases.
Included in
Amino Acids, Peptides, and Proteins Commons, Bacterial Infections and Mycoses Commons, Biochemistry, Biophysics, and Structural Biology Commons, Bioinformatics Commons, Computational Biology Commons, Genomics Commons, Microbiology Commons, Parasitic Diseases Commons, Pharmaceutics and Drug Design Commons, Therapeutics Commons