Structural and Functional Examination of a Nonribosomal Peptide Synthetase Producing β-lactone Antibiotics
Date of Award
Doctor of Philosophy (PhD)
With the amount of antibiotic resistant infections increasing and the number of new antibiotics entering the pharmaceutical pipeline decreasing, the need to develop new antibiotic is imperative. Utilizing bacteria’s biosynthetic pathways for antimicrobial secondary metabolite production, would allow for unique, complex, and stereoselective compounds to be tested for novel mechanisms of action. The work described herein utilizes a β-lactone forming nonribosomal peptide synthetase (NRPS) to form a library of analogs of the nonribosomal peptide (NRP) natural product, obafluorin. β-lactones are very reactive electrophiles that can form covalent bonds with a wide range of biological targets that may provide alternative mechanisms of action against highly resistant bacterial strains. Within this work, the crystal structure of the NRPS module obiF1 from Burkholderia diffusa is described along with functional studies utilizing the enzymes to investigate the substrate selectivity of the adenylation domain (A). Using combined enzyme assays of obiHDF from Pseudomonas fluorescens, a large library of different analogs probes the promiscuous nature of the transaldolase (obiH) and the NRPS enzymes (obiD and obiF). Among the diverse microbes that produce obafluorin, we were able to swap the NRPS domains and found ubiquitous interactions between the AAr and TAr domains. An organic synthetic route was optimized to yield obafluorin and its analogs in higher yields than can be isolated from culture. This work illuminates the usefulness of NRPS chemoenzymatic synthesis and domain swapping in order to make many possible strained-ring antibiotics.
Chair and Committee
Timothy A. Wencewicz
John-Stephen Taylor, Kevin D. Moeller, Joseph M. Jez, Meredith Jackrel,
Gemmell, Erin Marie, "Structural and Functional Examination of a Nonribosomal Peptide Synthetase Producing β-lactone Antibiotics" (2021). Arts & Sciences Electronic Theses and Dissertations. 2366.
Available for download on Saturday, January 10, 2026